At the moment I am writing these words, I am very excited to know that you are one of the first people to assemble the kits we have designed, thank you very much for your trust and your perseverance!
We have had this project on our hearts for 3 years and since only 6 months we have been able to invest enough time and resources to make it happen. I hope you really enjoy this experience and that you will be able to present your creation very soon. And, that we will have the opportunity to meet during a masterclass!
vital information to assemble your ego driver kit
If you are familiar with Do It Yourself with your effect pedals, you will find everything you need in this downloadable document.
If you’re just starting out, the rest of the article is really made for you, so hang in there! Download this document anyway, you will need it to move forward and understand the rest of the events. Then you’ll see it’ s very useful.
leave your soldering iron on for 2 minutes before we start
The assembly of a FX Teacher kit has nothing to do with what you have already found on the net. Indeed, we have developed our own method to assemble your PCB, step by step, and to constantly check its proper functioning! And yes, we are committed to the infallible, but you also have some work to do so.
So, in order for you to understand all the tricks we’re going to ask you to do, I suggest you to start by devouring all of our tutorials, if you haven’t already done so.
Congratulations you are finally starting to enjoy the joys of assembling an effect pedal! Your head is full of super condensed information, we’ll decompile all this with a bit of exercise!
We will also do everything we can to make sure you can get your kit up and working.
We warm up the soldering iron and let’s go!
Confessions: The neurons will also continue to heat up, sorry. But you’ll get out of it taller, I promise!
the power supply stage
electronic schematic
The power supply presented is not the same as for a Tube Screamer, for more headroom and a better filtering, we have added our personal touch! The power supply is first filtered by R22 and E4 and then when entering the TC1044 chip, it will create the -9V supply. The advantage is therefore to have +9 – (-9) = 18V of headroom. Then, we can feed our active circuits symmetrically!
The usual method is unfortunately to center the signal on 4.5V to be between ground and +9V. It sounds much better with our method you’ll see!
key points
Here is a short list of points to be considered before soldering. All the tricks are in the blog articles mentioned above.
Do not burn the SMT LED when soldering it. It’s made of plastic, it melts!
Wires +9V and GND must be inserted through the back of the PCB, on the solder side.
Insert the electrolytic capacitors with the correct angle.
Push the integrated circuit in the right side.
la bom
Name of the component
Value
Type
LED+
LED CREE
Surface mounted LED
R13
220Ω
Resistor
R22
10Ω
Resistor
E2, E3
10uF
Electrolytic capacitor
E4
100uF
Electrolytic capacitor
D3, D4
1N4001
Diodes
IC2
Socket DIP8
Integrated circuit socket
IC2
TC1044SCPA
Integrated circuit
expected result
Here’s what you should get after this step!
voltage measurements
Let’s plug in the multimeter and try to find more or less the same values (at 10% ready). I use a power supply that provides 9.35V so it influences the rest of the measurements. Start by discovering your power supply by measuring TP1. The Test Points (TP) are available at the end of the PDF file you downloaded. When assembling step by step, these values differ from the table in the document because we have not yet assembled everything. Once everything is assembled, the circuits consume current and the resistors cause some voltage drop! Hence the slight differences between the final table and the table that is being defined.
Test point
Measured voltage
TP1
9,35V
TP2
9,35V
TP3
-9,35V
2. the input buffer
electronic schematic
The first block that interacts with the signal is a transistor buffer stage. Here R1 is placed to unload any line capacity and avoid a “pop” at ignition. F1 and R2 form a high-pass filter that eliminates any continuous signal. The transistor is mounted in a common collector which allows a gain close to 1 in voltage and a significant gain in current. Its input impedance is highly dependent to R3. So we have a very interesting buffer. It is the same as the original Tube Screamer.
key points
Put the transistor on the right side
Put the resistors in the right order so that you don’t have to force to insert the last one
the bom
Name of the component
Value
Type
R1
1MΩ
Resistor
R2
1kΩ
Resistor
R3
470kΩ
Resistor
R4
10kΩ
Resistor
R5
100kΩ
Resistor
F1
22nF
Film condensator
F2
1uF
Film condensator
Q1
2N5088
Bipolar transistor
expected result
voltage measurement
The important voltage here is TP4 which is the polarization voltage of the transistor emitter.
Test point
Measured voltage
TP4
-1,74V
spectral analysis
In order to connect easily to the FX Teacher tester, we solder the following wires:
A white wire between R1 and F1: this will be the entry of our circuit
A green wire between R5 and F2: this will be the output of our circuit
Two black wires, one on G1 and one on G2, they will be the ground of the tester
As a reminder, here is how to connect the tester to a pedal. It’s not an Ego Driver, but it has the merit of enlightening you.
The tester is in place, we’re ready to go. We’re going to create two stimuli:
Sine of 1kHz to measure the gain of the circuit. Also, it will be possible to control the saturation rate of the system and notice the appearance of undesirable noise.
Frequency sweep made of sine waves from 20Hz to 20kHz, in order to know the filter gain on each frequency!
The expected result for this stage, with or without the effect, is only a 1kHz line with no harmonics (2kHz, 3kHz…). The spectrum must be completely flat because there is no amplification and we must preserve our signal.
1kHz on its own. No harmonics. Only a little bit of 50Hz captured by the measurement environment which is not perfect.
We now generate our “sweep” with an amplitude close to -34dBFs, because it is an amplitude close to a guitar level.
After measurement, we notice that all frequencies come out with more or less the same amplitude.
To summarize, our input buffer stage is completely flat in the bandwidth (it does not filter any useful frequencies) and does not saturate when you inject a sinus.
Perfect! Perfect! He does his job very well. Let’s move on!
3. the gain stage
electronic schematic
This first part of the gain block is made up of an operational amplifier or “OPA”.
This setup is called a non-inverting amplifier stage, the gain in the bandwidth is theoretically calculated by the 1+(R18+GAIN)/R12 ratio.
But all this depends on the filters created by R18+GAIN // C1 and R12 – F5.
Then, R11 and F6 are used as a low-pass filter to accentuate the mids and cut the highs that are a little too strident ! With a cut-off frequency at -3dB of 7kHz.
key points
Set the potentiometer on the right side of the PCB.
Put the IC in the right way.
the bom
Component name
Value
Type
R11
1kΩ
Resistor
R12
4,7kΩ
Resistor
R17
10kΩ
Resistor
R18
51kΩ
Resistor
F5
47nF
Film condensator
F6
220nF
Film condensator
F9
100nF
Film condensator
C1
47pF
Ceramic condensator
IC1
Socket DIP8
IC socket
IC1
4558P
IC
GAIN
A500k
Potentiometer
expected result
voltage measurements
Here the two important voltages to be checked are those of the integrated circuit power pins
Test point
Measured voltage
TP5
9,25V
TP6
-8,98V
frequency analysis
In terms of connections, the input is always the same because the stages are cascaded. And, we are adding one stage after the other so the input will not change until we have finished assembling the kit.
On the other hand, the output will regularly move according to our progress in the assembly of the kit. So here we connect the green wire between R11 and F6, as shown in the picture.
To understand how the gain stage works, we’ll start by putting our gain knob at maximum! Attention it will be necessary to lower the input level of the sound card until it is no longer saturated (when the vumeter is red it is necessary to lower until it is green).
We thus obtain a beautiful bump between 400Hz and 2kHz. That’s exactly what you expect from a Tube Screamer! Everything else is attenuated. Except for the 50Hz that annoys us but that we won’t have once the pedal is finished!
To know the gain (approximate and in the bandwidth) of the buffer + amp stage, we start by sending a 1kHz sinus when the effect is connected. We lower the input of the sound card so that it does not overload. For example, we note -7dB with our sound card setting.
Then, a jack is connected between the input and the output of the sound card, without touching the input level potentiometer.
This signal is injected again without modifying anything on the sound card, to obtain in this case, -41dB.
For the calculation of the gain: Gain = -7 – (-41) = 34dB.
It’s already huge!
Pretty simple method, right? If you want to know the gain for each frequency you repeat the experiment but with a sweep rather than a pure sinus.
4. clipping and voicing stage
electronic schematic
At this point if you listen to your gain stage, you might be a little disappointed! Its harmonic content is not remarkable, it will only try to saturate the input of your guitar amp.
We will therefore add clipping diodes, in order to cut the peaks of the sinusoidal signal and finally find them almost square!
Each diode cuts more or less high in amplitude according to its threshold voltage.
Regarding the voicing, you remember that the total gain of the amplification stage depends on 1+(R18+GAIN)/R12 (in theory, in the bandwidth).
Here we will modify R12 by switching to R10 and the BASS trimpot with the voicing switch.
Also, the bandwidth will be modified by choosing F4 at 1uF instead of F5 at 47nF. So we’re going to measure all this and discover our new spectral patterns for each of the possibilities!
key points
Solder the switches on the right side, solder side
Choose the right switch at the right place (ON-ON at the middle, so 2 positions for the CLIPPING, and ON-OFF-ON at the bottom left, so 3 positions for the VOICING). If you have a recent kit (from ego driver #690), we now give 2 ON-OFF-ON to not make any more mistakes, the central position of the clipping switch giving a position without clipping.
Mount the terminals in the right direction, with the holes facing upwards
Put the diodes in the right direction, look at the ring carefully
Set the trimpots at 3/4
the bom
Component name
Value
Type
R10
470Ω
Resistor
R21
470Ω
Resistor
F4
1uF
Electrolytic condensator
D1
1N914
Diodes
D2
1N914
Diodes
CAPS
Condensators
Terminal block
DIODES
Diodes
Terminal block
CUSTOM
20k
Trimpot
BASS
20k
Trimpot
VOICING
SPDT ON-OFF-ON
Commutateur à levier
CLIPPING
SPDT ON-ON (ON-OFF-ON from kit #690)
Toggle switch
terminals
Take the bag #7 and assemble the 3 small PCBs. There is one with the 2 LEDs, one with 2 x 1N4001, and one with 1N34 and 2x 2N7000. Be careful with the orientation of the components! For the diodes, there is the line drawn on the PCB, and for the LEDs, the longest leg corresponds to the + on the PCB.
The 1N34 being rare, they are sometimes replaced by D9E. The D9E are recognizable because they have a blue ring drawn. These diodes have the same characteristics as the 1N34, but need to be placed ON THE WRONG SIDE of the diagram drawn on the PCB.
PCB 1:
Component name
Value
Type
Q1, Q2
2N7000
Transistor
D1
1N34 (black ring)
Diode
D1 (on some kits, beware of reversed polarity)
D9E (blue ring)
Diode
1N34 or D9E. be careful, the direction of the diode is not the same according to the diode you receive!
PCB 2:
Component name
Value
Type
D1, D2
1N4001
Diode
PCB 3:
Component name
Value
Type
D1, D2
3mm LED
LED
Then place your favorite one in the diode terminal, and a capa in the capa terminal. In the team we prefer these: 1N34 + 2 x 2N7000 for the diodes, and 22nF for the capa! You can change them later to customize your drive.
The small clipping PCB and the capa in the terminals.
expected result
spectral analysis
For these measurements we use the same connection wires as the previous stage because we are located at the PCB input and at the output of the gain stage. The clipping is connected in parallel with the gain stage. So no physical modifications required.
We measure the sweep and the 1kHz signal in bypass (jack connected in the sound card without the board):
2. Pedal connected this time and all switches switched up. We can start the measurements.
The frequency sweep indicates that the bandwidth is now between 50Hz and 1.5kHZ. This is normal, when the voicing is at the top, it activates the branch that amplifies the basses!
The pure sine at 1kHz create harmonics. We notice that the 1st odd harmonic (3kHz) has a greater amplitude than the even harmonics (2kHz and 4kHz). This is due to clipping distortion from the diodes which has this very particular characteristic and opposite to valves! As we might be led to believe. It is mainly the valves of our preamplifiers that will saturate following the arrival of large amplitudes in the mediums and thus finally create our even harmonics.
3. Clip on top and voicing in the center. Same configuration as a classic Tube Screamer.
The sweep shows us a bandwidth between about 300Hz and 1.2kHz. So that’s what we love and expect from a Tube Screamer!
4. Voicing at the bottom and clipping at the bottom. We are now on the 22nF cap and on the diode pair of 1N34 and 2N7000 screwed on their respective terminals.
The capacitor being smaller than the original one, 22nF versus 47nF, we expect to operate a bit more in the high frequencies. And, this is the case with a bandwidth that goes from 450Hz to 1.5kHz. However, the difference remains less significant than when you boost the bass.
In terms of the differences in the harmonics of the sine at 1kHz, it is too small to notice it with this method. There you have to play and listen, ears are also very often excellent tools!
5. tone stack
electronic schematic
We start the Tone floor, a very important stage that allows us to find more or less highs at the output!
First of all, you should know that we didn’t have a “G” type potentiometer. This “G” curve of potentiometers allows a very musical logarithmic progression at the mid-range level.
We therefore faked it, by putting R19 and R20 in parallel of our B-type potentiometer, which offers a very similar result.
To understand this layout, it is necessary to go to the 2 extremes of the Tone pot. Here are the equivalent diagrams when it is at the maximum and then at the minimum:
Quand la Tone est à fond
Quand la tone est au minimum
When the pot is at full throttle, the gain created by the OPA depends on R16, R15 and F7. Knowing that R15 and F7 cut at 3kHz and that R16 is larger than R15, we amplify the high frequencies well.
When the pot is at minimum, the gain is very close to the unit because it is equal to 1+R16/R1 or about 1.2. While at the input, the couple F7 and R15 form a beautiful low pass filter at 3kHz.
We can better understand why aficionados are thrilled by a Tube Screamer Tone, we can gradually switch from a filter that cuts the high frequencies to a filter that amplifies them!
key points
Assemble the potentiometer on the right side of the board, solder side
Put the resistance in the right order, follow the BOM
the bom
Component name
Value
Type
R14
1kΩ
Résistance
R15
220Ω
Resistor
R16
1kΩ
Resistor
R19
6,8kΩ
Resistor
R20
6,8kΩ
Resistor
F7
220nF
Film condensator
F8
1uF
Electrolytic condensator
TONE
B25k
Potentiometer
OUT
B100k
Potentiometer
excepted result
spectral analysis
Start by placing the green wire at the end of the new stage, i.e. on the middle tab of the volume pot.
We keep the gain and volume at maximum, the voicing switch in the middle and then the clipping switch at the top.
As we are on the same configuration as before, except for the Tone, we can take for reference in our measurements, the spectrum of the previous step as follows. (the one at the gain output with clipping at the top and voicing in the middle)
With the tone at its maximum, here is what we measure:
The peak is closer to 1.5kHz than 700Hz.
With the tone at minimum:
The peak drops to around 500Hz.
This curve reflects the theoretical performance of the Tone stage, when the tone is at minimum, the bass and low-midrange frequencies are pushed out, while the high frequencies are filtered out.
When the tone is at its maximum, on the opposite, we add trebles and break through the mix. So it’s up to you to find the right compromise that you like the most!
6. the output buffer
electronic schematic
And finally the last block! Almost identical to the one at the entrance. Its purpose is to adapt the signal after all the processing that has just been done to it. This way, it will be ready to pass without any problems to the next pedals!
key points
Solder the transistor on the right flip
Put the resistors in the right order so as not to have to force the last one in.
the bom
Component name
Value
Type
R6
470kΩ
Resistor
R7
10kΩ
Resistor
R8
100Ω
Resistor
R9
10kΩ
Resistor
F3
100nF
Film condensator
E1
10uF
Electrolytic condensator
Q2
2N5088
Bipolar transistor
expected result
voltage measurements
The important voltage to measure here is TP8. This is the polarization voltage of the output transistor.
Test point
Measured voltage
TP8
-1,74V
Spectral analysis
By putting the same settings as in the previous test and the Tone at noon, we should not change anything and have a similar result at the gain stage:
One bump around 800Hz and we cut around it!
okay, so what now?
The most difficult part is done! Your board works perfectly, you will be able to transform it so that it fits perfectly into your enclosure and you can finally take it with you from everywhere.
If you have any questions, comments…. Feel free to ask them here in comment. Meanwhile I hope you liked this first kit and that we will find you soon for the next ones!
Stay in the motion and go follow the last 2 articles to finish your pedal!
I have now assembled the device and followed all your instructions with clean soldering. That said when I plug the pedal into my amp, it has very low volume output which means the gain is very hard to discern and it lowers my amp volume with output at 100%. Any suggestions as to where to trouble shoot this problem on the PCB. Soldering all looks good with no spillover.
Hi Craig,
Do you have the values of the test points, and the signal measurements? It might help to see on which step the problem is located.
Have a nice day,
Loick
Hello Loïck, j’ai monté mon Ego Driver hier (je monte assez régulièrement des pédales) hier et j’ai deux soucis, et comme j’ai pas eu encore le temps d’investiguer (je vais vérifier les tensions sur la pump charge puis je vérifierai la chaine du buffer d’entrée pour remonter jusqu’au buffer de sortie), je voudrais savoir si tu as une idée en lien avec les symptômes, le true bypass fonctionne bien mais la LED reste très légèrement allumée, et lorsque j’active la pédale, la LED est allumée normalement mais le signal de sortie est faible, pas saturé et les potards ne semblent apporter aucune modification. J’ai pensé à un problème de masse, G, G1 et G2 sont bien reliées au même potentiel (ou masses isolées) ?
Re Loïck,
Mes points de tests TP1 à TP7 sont nickels, en revanche le point de test TP8 qui doit correspondre à la polarisation du transistor Q2 (buffer de sortie) à une valeur assez différente par rapport à ce que vous indiquez (-1,16V chez moi alors que vous mesurez -1,56V), je précise que j’ai vérifié le code couleur de R7 (qui est reliée à l’émetteur de Q2) qui est bien conforme (10K ohms) et j’avais vérifié sa valeur à l’ohmètre avant de la souder.
En revanche j’ai remarqué que les 2 transistors 2N5088 fournis ne sont visiblement pas de la même marque.
Merci de me tenir au courant.
Très bonne nouvelle, il ne devait pas y avoir grand chose, après les tests et quelques manipulations sur le footswitch, tout fonctionne à merveille, et elle sonne divinement ! 😃
Salut Sébastien,
Merci pour tes retours, ton problème ressemble à un faux contact de la masse au niveau du footswitch. Content de savoir que finalement tout fonctionne 🙂
Bonne journée,
Loick
Geoffrey Bouillon
Hello,
Voilà j’ai un petit soucis avec mon Ego Driver.
Quand j’appuis sur le bypass (led allumé, je n’ai plus de son, ça coupe)
Quoi faire pour régler ce problème ?
Je n’ai pas testé au fur et à mesure…
Voilà les valeurs aux tests si cela peut aider :
TP1 : 9.35 au lieu de 9.33 = à mon avis ok
TP2 : 8.95 au lieu de 8.93 = à mon avis ok
TP3 : 0.27 au lieu de -8.71 = à mon avis mauvais
TP4 : 0.27 au lieu de -1.61 = à mon avis mauvais
TP5 : 8.95 au lieu de 8.93 = à mon avis ok
TP6 : 0.27 au lieu de -8.71 = à mon avis mauvais
TP7 : 6.13 au lieu de 6.08 = à mon avis ok
TP8 : 0.27 au lieu de -1.56 = à mon avis mauvais
Merci par avance pour votre retour, car là je sèche !!
Alors ! En regardant ton relevé de tensions, ce qui est bien c’est qu’on voit très clairement qu’il y a un problème.
Si on regarde bien, on n’a pas de tensions négatives…
D’après toi c’est quel composant qui est mort du coup ? 🙂
Si t’as pas les tensions négatives c’est que l’IC qui génère ces tensions ne marche plus, il faut donc le remplacer 🙂
Pour le sifflement c’est que tu tire trop de courant quelque part, faux contact ou transistor à l’envers tien !
Reprends tout étape par étape, utilise le testeur FX Teacher et analyse les problèmes un à un en suivant l’article 😉
Tu as de la chance, y’a le temps pendant le confinement !
Merci Alex, je pense que cela doit venir du transistor en effet !
Y’a plus qu’à tester et tout reprendre étape par étape.
A suivre…
A samedi pour la masterclass de la sliver !
Geoff
Re…
Bon, ben je trouve pas le problème… HELP !!!
J’ai les bonnes tension, et quand j’active le bypass, plus de son mais un sifflement !
J’ai testé presque tous les composants… franchement je sèche…
Si tu as une idée, avant je recommande une PCB et un kit électro complet pour la refaire…
Merci par avance 😉
Geoff
Envoi nous un nouveau relevé de tensions et des photos stp !
Pour les photos faut que tu trouve un hébergeur et que tu mettes les liens ici.
Je vais essayer de voir ce qu’il se passe mais je te promets rien 😉
Bon courage,
Alex.
Christian Huthmacher
I seem to be having a grounding issue when the CLIP switch is in the DOWN position. It its fine in the UP position.But when it is DOWN it is crazy over saturated. I put the LED DIODE in so I could visualize the current, and the LEDs where bright red. Taking the innards out of the enclosed fixed the issue immediately. I triple checked my ground connections and everything is in order. I triaged the issue by lining the the IN and OUT 1/4 jack holes with duct tape. But this introduced a new issue: I can’t touch any metal on the pedal or it will make the most unpleasant screech. I don’t know how to fix this, and it’s really a bummer, the pedal sounds great when it works.
Hi! When it’s down you are connected to the clipping of your choice 🙂
You don’t need to isolate your jack from the enclosure, the ground loop is well engineered if you follow the true bypass instructions.
Hi! As of now I do not have the schema of the Test points but I believe that TP4 should be on the leg on the “inside” of the resistor (considering how things are connected, based on schema above and what I could make of the wiring on the PCB.
My tension seems to be -1.57V there instead of -1.74V but I would assume that is acceptable because of components variability (I guess we are talking about a 10% difference here?). What do you think?
For the test with Audacity I am using a Boss GT1 which acts as an audio interface but I am assuming that I would need to have the interface to have also an output that comes for what is generated by audaticity am I right? Otherwise the tests does not do anything? Differently said: a multi effect audio interface would not be suitable for this test right?
Thanks for the help and great project! I am having quite a bit of fun figuring things out.
Hi! Yes -1.57V seems correct 🙂
For the audio interface, yes, you need to inject the signal that comes from Audacity into the pedal input, and then get it back on Audacity once it’ s passed in the pedal. We use the Focusrite Scarlett, but you can use any interface that has outputs for monitor speakers and an instrument input.
Loick
My multimeter cannot show negative values so for most of the negative values it is showing either 3.21 volts or values below 1 millivolt, is this okay? And I am extremely new to pedal building since I am twelve so any advice would mean the world to me!
Hi, I assembled the pedal. All TP are corrrect, led turns on when switch is engaged but I’m getting no sound out of the pedal. Not even on bypass. Any ideas on how to test where’s the problem?
Hi!
If you don’t have sound on bypass, then it probably comes from the jack wiring, or 3PDT switch. Check that the white, green and black wires are connected to the correct pins of the jack. Then see if you get a signal on the wire pads on the pcb, and the pads of the 3PDT pcb.
Loick
I wired the 3PDT manually and got bypass to work. Now I got static when the pedal is engaged and clipping switch is UP. When I switch the clipping switch the static goes away.
I have finally succeeded with building the Ego Driver, woohoo!
I have hit 3 issues while doing so that might be worth mentioning for others building the project.
a) Make sure only one of the 6.3mm jacks is grounded. When you complete the project, both jacks will be connected via the chassi of the pedal which means if they are both connected to ground you will create a ground loop that will kill the signal.
b) Make sure the power supply is not a cheap one. I was using one of those universal power supplies but it is known that with OD pedals they cause interference and a lot of weird noises.
c) Be careful where you connect your cables to the jacks. I connected the green cable to the wrong pin of the output jack and the result was that the volume was super low 🙂
Hey,
i assembled everything and i have the following problem:
When i turn the pedal off, the LED is still on, but glows weakly. My clean guitar comes through tho.
But when i turn it on, a constant high pitch sound is emitted from the pedal.
When i turn the tone knob or any other switch, even on the guitar, the pitch changes.
Do you have maybe an idea, where this is coming from?
Hello!
I have completed the build and all seems to be working well apart from the tone knob. When it is all the way down and all the way up, it works as it is meant to, but anywhere in between the tone sounds like it is exactly halfway. At 2 its sounds to exact same as if it was at 9. I have checked all components and they appear to be in the correct positions so I am not sure what the issue is.
Other than that the pedal is working well
I was rushing and had a slight mishap when connecting my pedal for one of the last tests, BEFORE installing the 3PDT switch, and resistor R22 started smoking. I immediately disconnected power, and while R22 had some slight discoloration, I tested it with an Ohmmeter and it read the correct value (10 ohms). I connected everything and ran the sweep and 1kHz tone and everything surprisingly looked ok.
However, after installing the 3PDT switch, the led doesn’t come on. I went back and tested all the test points, and the only one that I couldn’t get a value at was TP7. I tested that resistor (R13, just above the LED) and it showed the correct value (220ohms).
It’s strange that I had a good test signal before installing the 3PDT switch. I also tested the terminals on the 3PDT switch to see if the switch was good, and it seems to be ok.
I went ahead and tested the pedal with a guitar anyways, and everything seems to be working correctly, except there is no LED light. Is a blown LED the reason I wouldn’t get a voltage at TP7?
Hi,
Glad the pedal still works well! If you don’t have a value on TP7 then yes it’s coming from the LED. You can test the voltages directly on the LED. You should have one side (anode) which should always be at 9V (or the same value as TP2), and the other side (cathode) which corresponds to TP7. You can also test with an ohmmeter that the anode is connected to TP2 and the cathode to TP7 and R13. The other side of R13 must be connected to pin L- of the footswitch. If everything is good then maybe the LED is burnt out!
Hi Loick. Thanks for the reply. Everything looks good except I don’t get any voltage on the (-) side of the LED. The (+) side was 9v. It appears I have continuity everywhere else, so it sounds like the culprit is the LED?
Any recommendations on a replacement (e.g. from mouser)? Any tips for desoldering the old one and putting on the new one? I guess I’ll be learning surface mount soldering now! 🙂
Hi,
Sorry for the late reply. Desoldering a surface mount component is not easy, the best is to use desoldering wick or pump and slightly lifting the component with pliers or a flathead screwdriver. You can contact us at [email protected] for spare parts.
Have a nice day,
Loick
Russ B
Finished the pedal and all switches and knobs worked for 1 minute, but was slightly noisy when tapping the knobs. Then a kind of splat! noise and now the fuzz is way up, no gain or tone control, no switches work, and the volume knob peaks at 7 then tapers back down. Also when guitar signal volume is low the pedal sputters and then limits out all signal, like a noise gate. Can provide video example if needed. Thank you!
Hi,
Did you do the step by step analysis as recommended in the assembly article? It will be much easier to know where the problem comes from.
If the problem came afterwards, you can try to visualize the signal between each step, to identify which step is the problem.
Have a nice day,
Sorry for the long delay in reply. When testing each test point, none of the readings correspond to the values provided in the pdf. Nor do my readings stay the same. For instance, tp1 readings fluctuate between 47.6, 0.00, and 5.73. This is similar across all test points.
It seems that you have a problem with the power supply. Make sure your external power supply, and the wiring of the power supply connector are ok, TP1 is connected directly to the power supply connector, without going through any component.
Also check the power consumption of the pedal, an abnormally high consumption (more than 100mA) could indicate a short circuit somewhere.
A power supply that is too low can explain the noise gate effect.
Have a nice day,
Loick
English
Français
assemble your ego driver
At the moment I am writing these words, I am very excited to know that you are one of the first people to assemble the kits we have designed, thank you very much for your trust and your perseverance!
We have had this project on our hearts for 3 years and since only 6 months we have been able to invest enough time and resources to make it happen. I hope you really enjoy this experience and that you will be able to present your creation very soon. And, that we will have the opportunity to meet during a masterclass!
vital information to assemble your ego driver kit
If you are familiar with Do It Yourself with your effect pedals, you will find everything you need in this downloadable document.
If you’re just starting out, the rest of the article is really made for you, so hang in there! Download this document anyway, you will need it to move forward and understand the rest of the events. Then you’ll see it’ s very useful.
leave your soldering iron on for 2 minutes before we start
The assembly of a FX Teacher kit has nothing to do with what you have already found on the net. Indeed, we have developed our own method to assemble your PCB, step by step, and to constantly check its proper functioning! And yes, we are committed to the infallible, but you also have some work to do so.
So, in order for you to understand all the tricks we’re going to ask you to do, I suggest you to start by devouring all of our tutorials, if you haven’t already done so.
Here they are, in order:
now we can start!
Congratulations you are finally starting to enjoy the joys of assembling an effect pedal! Your head is full of super condensed information, we’ll decompile all this with a bit of exercise!
We will also do everything we can to make sure you can get your kit up and working.
We warm up the soldering iron and let’s go!
Confessions: The neurons will also continue to heat up, sorry. But you’ll get out of it taller, I promise!
the power supply stage
electronic schematic
The power supply presented is not the same as for a Tube Screamer, for more headroom and a better filtering, we have added our personal touch! The power supply is first filtered by R22 and E4 and then when entering the TC1044 chip, it will create the -9V supply. The advantage is therefore to have +9 – (-9) = 18V of headroom. Then, we can feed our active circuits symmetrically!
The usual method is unfortunately to center the signal on 4.5V to be between ground and +9V. It sounds much better with our method you’ll see!
key points
Here is a short list of points to be considered before soldering. All the tricks are in the blog articles mentioned above.
la bom
expected result
Here’s what you should get after this step!
voltage measurements
Let’s plug in the multimeter and try to find more or less the same values (at 10% ready). I use a power supply that provides 9.35V so it influences the rest of the measurements. Start by discovering your power supply by measuring TP1. The Test Points (TP) are available at the end of the PDF file you downloaded. When assembling step by step, these values differ from the table in the document because we have not yet assembled everything. Once everything is assembled, the circuits consume current and the resistors cause some voltage drop! Hence the slight differences between the final table and the table that is being defined.
2. the input buffer
electronic schematic
The first block that interacts with the signal is a transistor buffer stage. Here R1 is placed to unload any line capacity and avoid a “pop” at ignition. F1 and R2 form a high-pass filter that eliminates any continuous signal. The transistor is mounted in a common collector which allows a gain close to 1 in voltage and a significant gain in current. Its input impedance is highly dependent to R3. So we have a very interesting buffer. It is the same as the original Tube Screamer.
key points
the bom
expected result
voltage measurement
The important voltage here is TP4 which is the polarization voltage of the transistor emitter.
spectral analysis
In order to connect easily to the FX Teacher tester, we solder the following wires:
Now, the PCB is connected to the sound card using the FX Teacher method.
The tester is in place, we’re ready to go. We’re going to create two stimuli:
The expected result for this stage, with or without the effect, is only a 1kHz line with no harmonics (2kHz, 3kHz…). The spectrum must be completely flat because there is no amplification and we must preserve our signal.
We now generate our “sweep” with an amplitude close to -34dBFs, because it is an amplitude close to a guitar level.
After measurement, we notice that all frequencies come out with more or less the same amplitude.
To summarize, our input buffer stage is completely flat in the bandwidth (it does not filter any useful frequencies) and does not saturate when you inject a sinus.
Perfect! Perfect! He does his job very well. Let’s move on!
3. the gain stage
electronic schematic
This first part of the gain block is made up of an operational amplifier or “OPA”.
This setup is called a non-inverting amplifier stage, the gain in the bandwidth is theoretically calculated by the 1+(R18+GAIN)/R12 ratio.
But all this depends on the filters created by R18+GAIN // C1 and R12 – F5.
Then, R11 and F6 are used as a low-pass filter to accentuate the mids and cut the highs that are a little too strident ! With a cut-off frequency at -3dB of 7kHz.
key points
the bom
expected result
voltage measurements
Here the two important voltages to be checked are those of the integrated circuit power pins
frequency analysis
In terms of connections, the input is always the same because the stages are cascaded. And, we are adding one stage after the other so the input will not change until we have finished assembling the kit.
On the other hand, the output will regularly move according to our progress in the assembly of the kit. So here we connect the green wire between R11 and F6, as shown in the picture.
To understand how the gain stage works, we’ll start by putting our gain knob at maximum! Attention it will be necessary to lower the input level of the sound card until it is no longer saturated (when the vumeter is red it is necessary to lower until it is green).
We thus obtain a beautiful bump between 400Hz and 2kHz. That’s exactly what you expect from a Tube Screamer! Everything else is attenuated. Except for the 50Hz that annoys us but that we won’t have once the pedal is finished!
To know the gain (approximate and in the bandwidth) of the buffer + amp stage, we start by sending a 1kHz sinus when the effect is connected. We lower the input of the sound card so that it does not overload. For example, we note -7dB with our sound card setting.
Then, a jack is connected between the input and the output of the sound card, without touching the input level potentiometer.
This signal is injected again without modifying anything on the sound card, to obtain in this case, -41dB.
For the calculation of the gain: Gain = -7 – (-41) = 34dB.
It’s already huge!
Pretty simple method, right? If you want to know the gain for each frequency you repeat the experiment but with a sweep rather than a pure sinus.
4. clipping and voicing stage
electronic schematic
At this point if you listen to your gain stage, you might be a little disappointed! Its harmonic content is not remarkable, it will only try to saturate the input of your guitar amp.
We will therefore add clipping diodes, in order to cut the peaks of the sinusoidal signal and finally find them almost square!
Each diode cuts more or less high in amplitude according to its threshold voltage.
Regarding the voicing, you remember that the total gain of the amplification stage depends on 1+(R18+GAIN)/R12 (in theory, in the bandwidth).
Here we will modify R12 by switching to R10 and the BASS trimpot with the voicing switch.
Also, the bandwidth will be modified by choosing F4 at 1uF instead of F5 at 47nF. So we’re going to measure all this and discover our new spectral patterns for each of the possibilities!
key points
If you have a recent kit (from ego driver #690), we now give 2 ON-OFF-ON to not make any more mistakes, the central position of the clipping switch giving a position without clipping.
the bom
(ON-OFF-ON from kit #690)
terminals
Take the bag #7 and assemble the 3 small PCBs. There is one with the 2 LEDs, one with 2 x 1N4001, and one with 1N34 and 2x 2N7000. Be careful with the orientation of the components! For the diodes, there is the line drawn on the PCB, and for the LEDs, the longest leg corresponds to the + on the PCB.
The 1N34 being rare, they are sometimes replaced by D9E. The D9E are recognizable because they have a blue ring drawn. These diodes have the same characteristics as the 1N34, but need to be placed ON THE WRONG SIDE of the diagram drawn on the PCB.
PCB 1:
PCB 2:
PCB 3:
Then place your favorite one in the diode terminal, and a capa in the capa terminal. In the team we prefer these: 1N34 + 2 x 2N7000 for the diodes, and 22nF for the capa! You can change them later to customize your drive.
expected result
spectral analysis
For these measurements we use the same connection wires as the previous stage because we are located at the PCB input and at the output of the gain stage. The clipping is connected in parallel with the gain stage. So no physical modifications required.
2. Pedal connected this time and all switches switched up. We can start the measurements.
The frequency sweep indicates that the bandwidth is now between 50Hz and 1.5kHZ. This is normal, when the voicing is at the top, it activates the branch that amplifies the basses!
The pure sine at 1kHz create harmonics. We notice that the 1st odd harmonic (3kHz) has a greater amplitude than the even harmonics (2kHz and 4kHz). This is due to clipping distortion from the diodes which has this very particular characteristic and opposite to valves! As we might be led to believe. It is mainly the valves of our preamplifiers that will saturate following the arrival of large amplitudes in the mediums and thus finally create our even harmonics.
3. Clip on top and voicing in the center. Same configuration as a classic Tube Screamer.
The sweep shows us a bandwidth between about 300Hz and 1.2kHz. So that’s what we love and expect from a Tube Screamer!
4. Voicing at the bottom and clipping at the bottom. We are now on the 22nF cap and on the diode pair of 1N34 and 2N7000 screwed on their respective terminals.
The capacitor being smaller than the original one, 22nF versus 47nF, we expect to operate a bit more in the high frequencies. And, this is the case with a bandwidth that goes from 450Hz to 1.5kHz. However, the difference remains less significant than when you boost the bass.
In terms of the differences in the harmonics of the sine at 1kHz, it is too small to notice it with this method. There you have to play and listen, ears are also very often excellent tools!
5. tone stack
electronic schematic
We start the Tone floor, a very important stage that allows us to find more or less highs at the output!
First of all, you should know that we didn’t have a “G” type potentiometer. This “G” curve of potentiometers allows a very musical logarithmic progression at the mid-range level.
We therefore faked it, by putting R19 and R20 in parallel of our B-type potentiometer, which offers a very similar result.
To understand this layout, it is necessary to go to the 2 extremes of the Tone pot. Here are the equivalent diagrams when it is at the maximum and then at the minimum:
When the pot is at full throttle, the gain created by the OPA depends on R16, R15 and F7. Knowing that R15 and F7 cut at 3kHz and that R16 is larger than R15, we amplify the high frequencies well.
When the pot is at minimum, the gain is very close to the unit because it is equal to 1+R16/R1 or about 1.2. While at the input, the couple F7 and R15 form a beautiful low pass filter at 3kHz.
We can better understand why aficionados are thrilled by a Tube Screamer Tone, we can gradually switch from a filter that cuts the high frequencies to a filter that amplifies them!
key points
the bom
excepted result
spectral analysis
Start by placing the green wire at the end of the new stage, i.e. on the middle tab of the volume pot.
We keep the gain and volume at maximum, the voicing switch in the middle and then the clipping switch at the top.
As we are on the same configuration as before, except for the Tone, we can take for reference in our measurements, the spectrum of the previous step as follows. (the one at the gain output with clipping at the top and voicing in the middle)
With the tone at its maximum, here is what we measure:
With the tone at minimum:
This curve reflects the theoretical performance of the Tone stage, when the tone is at minimum, the bass and low-midrange frequencies are pushed out, while the high frequencies are filtered out.
When the tone is at its maximum, on the opposite, we add trebles and break through the mix. So it’s up to you to find the right compromise that you like the most!
6. the output buffer
electronic schematic
And finally the last block! Almost identical to the one at the entrance. Its purpose is to adapt the signal after all the processing that has just been done to it. This way, it will be ready to pass without any problems to the next pedals!
key points
the bom
expected result
voltage measurements
The important voltage to measure here is TP8. This is the polarization voltage of the output transistor.
Spectral analysis
By putting the same settings as in the previous test and the Tone at noon, we should not change anything and have a similar result at the gain stage:
okay, so what now?
The most difficult part is done! Your board works perfectly, you will be able to transform it so that it fits perfectly into your enclosure and you can finally take it with you from everywhere.
If you have any questions, comments…. Feel free to ask them here in comment. Meanwhile I hope you liked this first kit and that we will find you soon for the next ones!
Stay in the motion and go follow the last 2 articles to finish your pedal!
47 replies to “assemble your ego driver”
alexandre ernandez
Got a question ? Leave it here 🙂
Craig M
I have now assembled the device and followed all your instructions with clean soldering. That said when I plug the pedal into my amp, it has very low volume output which means the gain is very hard to discern and it lowers my amp volume with output at 100%. Any suggestions as to where to trouble shoot this problem on the PCB. Soldering all looks good with no spillover.
Loick Jouaud
Hi Craig,
Do you have the values of the test points, and the signal measurements? It might help to see on which step the problem is located.
Have a nice day,
Loick
Xavier
Hi, my 3PDT switch doesn’t latch. Can I get some support to get a new one?
Thanks
Loick Jouaud
Hi Xavier,
You can purchase a new 3PDT footswitch here : https://anasounds.com/produit/3pdt/
Or contact us at [email protected] if you need other spare parts.
Have a nice day,
Loick
Sébastien MARMET
Hello Loïck, j’ai monté mon Ego Driver hier (je monte assez régulièrement des pédales) hier et j’ai deux soucis, et comme j’ai pas eu encore le temps d’investiguer (je vais vérifier les tensions sur la pump charge puis je vérifierai la chaine du buffer d’entrée pour remonter jusqu’au buffer de sortie), je voudrais savoir si tu as une idée en lien avec les symptômes, le true bypass fonctionne bien mais la LED reste très légèrement allumée, et lorsque j’active la pédale, la LED est allumée normalement mais le signal de sortie est faible, pas saturé et les potards ne semblent apporter aucune modification. J’ai pensé à un problème de masse, G, G1 et G2 sont bien reliées au même potentiel (ou masses isolées) ?
Sébastien MARMET
Re Loïck,
Mes points de tests TP1 à TP7 sont nickels, en revanche le point de test TP8 qui doit correspondre à la polarisation du transistor Q2 (buffer de sortie) à une valeur assez différente par rapport à ce que vous indiquez (-1,16V chez moi alors que vous mesurez -1,56V), je précise que j’ai vérifié le code couleur de R7 (qui est reliée à l’émetteur de Q2) qui est bien conforme (10K ohms) et j’avais vérifié sa valeur à l’ohmètre avant de la souder.
En revanche j’ai remarqué que les 2 transistors 2N5088 fournis ne sont visiblement pas de la même marque.
Merci de me tenir au courant.
Sébastien MARMET
Très bonne nouvelle, il ne devait pas y avoir grand chose, après les tests et quelques manipulations sur le footswitch, tout fonctionne à merveille, et elle sonne divinement ! 😃
Loick Jouaud
Salut Sébastien,
Merci pour tes retours, ton problème ressemble à un faux contact de la masse au niveau du footswitch. Content de savoir que finalement tout fonctionne 🙂
Bonne journée,
Loick
Geoffrey Bouillon
Hello,
Voilà j’ai un petit soucis avec mon Ego Driver.
Quand j’appuis sur le bypass (led allumé, je n’ai plus de son, ça coupe)
Quoi faire pour régler ce problème ?
Je n’ai pas testé au fur et à mesure…
Voilà les valeurs aux tests si cela peut aider :
TP1 : 9.35 au lieu de 9.33 = à mon avis ok
TP2 : 8.95 au lieu de 8.93 = à mon avis ok
TP3 : 0.27 au lieu de -8.71 = à mon avis mauvais
TP4 : 0.27 au lieu de -1.61 = à mon avis mauvais
TP5 : 8.95 au lieu de 8.93 = à mon avis ok
TP6 : 0.27 au lieu de -8.71 = à mon avis mauvais
TP7 : 6.13 au lieu de 6.08 = à mon avis ok
TP8 : 0.27 au lieu de -1.56 = à mon avis mauvais
Merci par avance pour votre retour, car là je sèche !!
alexandre ernandez
Alors ! En regardant ton relevé de tensions, ce qui est bien c’est qu’on voit très clairement qu’il y a un problème.
Si on regarde bien, on n’a pas de tensions négatives…
D’après toi c’est quel composant qui est mort du coup ? 🙂
Geoffrey Bouillon
et oui j’avais bien vu 😉
Je dirai une des diodes ?? c’est ça ?
Geoffrey Bouillon
ou plutôt le circuit imprimé ?
Geoffrey Bouillon
C’est bon j’ai trouvé.
Le circuit intégré du bloc d’alim était grillé et le transistor Q2 était à l’envers 😉
Geoffrey Bouillon
Salut Alex,
J’ai maintenant les valeurs du tableau, mais quand j’allume le bypass ça sile !
alexandre ernandez
Si t’as pas les tensions négatives c’est que l’IC qui génère ces tensions ne marche plus, il faut donc le remplacer 🙂
Pour le sifflement c’est que tu tire trop de courant quelque part, faux contact ou transistor à l’envers tien !
Reprends tout étape par étape, utilise le testeur FX Teacher et analyse les problèmes un à un en suivant l’article 😉
Tu as de la chance, y’a le temps pendant le confinement !
Bon courage,
Alex
Geoffrey Bouillon
Merci Alex, je pense que cela doit venir du transistor en effet !
Y’a plus qu’à tester et tout reprendre étape par étape.
A suivre…
A samedi pour la masterclass de la sliver !
Geoff
Geoffrey Bouillon
Re…
Bon, ben je trouve pas le problème… HELP !!!
J’ai les bonnes tension, et quand j’active le bypass, plus de son mais un sifflement !
J’ai testé presque tous les composants… franchement je sèche…
Si tu as une idée, avant je recommande une PCB et un kit électro complet pour la refaire…
Merci par avance 😉
Geoff
alexandre ernandez
Hey 🙂
Envoi nous un nouveau relevé de tensions et des photos stp !
Pour les photos faut que tu trouve un hébergeur et que tu mettes les liens ici.
Je vais essayer de voir ce qu’il se passe mais je te promets rien 😉
Bon courage,
Alex.
Christian Huthmacher
I seem to be having a grounding issue when the CLIP switch is in the DOWN position. It its fine in the UP position.But when it is DOWN it is crazy over saturated. I put the LED DIODE in so I could visualize the current, and the LEDs where bright red. Taking the innards out of the enclosed fixed the issue immediately. I triple checked my ground connections and everything is in order. I triaged the issue by lining the the IN and OUT 1/4 jack holes with duct tape. But this introduced a new issue: I can’t touch any metal on the pedal or it will make the most unpleasant screech. I don’t know how to fix this, and it’s really a bummer, the pedal sounds great when it works.
alexandre ernandez
Hi! When it’s down you are connected to the clipping of your choice 🙂
You don’t need to isolate your jack from the enclosure, the ground loop is well engineered if you follow the true bypass instructions.
Armando Miraglia
Hi! As of now I do not have the schema of the Test points but I believe that TP4 should be on the leg on the “inside” of the resistor (considering how things are connected, based on schema above and what I could make of the wiring on the PCB.
My tension seems to be -1.57V there instead of -1.74V but I would assume that is acceptable because of components variability (I guess we are talking about a 10% difference here?). What do you think?
For the test with Audacity I am using a Boss GT1 which acts as an audio interface but I am assuming that I would need to have the interface to have also an output that comes for what is generated by audaticity am I right? Otherwise the tests does not do anything? Differently said: a multi effect audio interface would not be suitable for this test right?
Thanks for the help and great project! I am having quite a bit of fun figuring things out.
Loick Jouaud
Hi! Yes -1.57V seems correct 🙂
For the audio interface, yes, you need to inject the signal that comes from Audacity into the pedal input, and then get it back on Audacity once it’ s passed in the pedal. We use the Focusrite Scarlett, but you can use any interface that has outputs for monitor speakers and an instrument input.
Loick
Sherin Abdul Majeed
Hey, Alex
My multimeter cannot show negative values so for most of the negative values it is showing either 3.21 volts or values below 1 millivolt, is this okay? And I am extremely new to pedal building since I am twelve so any advice would mean the world to me!
Thank you in advance,
Arhaan.
Sherin Abdul Majeed
Hey Alex,
Since it is showing as 3.21 volts I was worried if the 18 volt headroom would be there or not
Thanks!
alexandre ernandez
Hi, the best way to try is to invert your multimeter leads to show the value in the positive side 🙂
platoon16
Hi, I assembled the pedal. All TP are corrrect, led turns on when switch is engaged but I’m getting no sound out of the pedal. Not even on bypass. Any ideas on how to test where’s the problem?
Loick Jouaud
Hi!
If you don’t have sound on bypass, then it probably comes from the jack wiring, or 3PDT switch. Check that the white, green and black wires are connected to the correct pins of the jack. Then see if you get a signal on the wire pads on the pcb, and the pads of the 3PDT pcb.
Loick
platoon16
I wired the 3PDT manually and got bypass to work. Now I got static when the pedal is engaged and clipping switch is UP. When I switch the clipping switch the static goes away.
alexandre ernandez
Hi! Why didn’t you used our 3PDT PCB? I don’t know the wiring you used then.
Armando Miraglia
I have finally succeeded with building the Ego Driver, woohoo!
I have hit 3 issues while doing so that might be worth mentioning for others building the project.
a) Make sure only one of the 6.3mm jacks is grounded. When you complete the project, both jacks will be connected via the chassi of the pedal which means if they are both connected to ground you will create a ground loop that will kill the signal.
b) Make sure the power supply is not a cheap one. I was using one of those universal power supplies but it is known that with OD pedals they cause interference and a lot of weird noises.
c) Be careful where you connect your cables to the jacks. I connected the green cable to the wrong pin of the output jack and the result was that the volume was super low 🙂
Have fun!
Cheers,
Armando
Loick Jouaud
Hi! Thank you very much for your feedback, and glad to see that you built it successfully 🙂
It can be helpful for other makers
Loick
Sam
Hello, I have assembled the pedal and it functions but the LED won’t turn on. How would I go about repairing this issue?
alexandre ernandez
Hey 🙂 Please check your true bypass step, it can be a wrong contact in the 3PDT.
Maik Mursall
Hey,
i assembled everything and i have the following problem:
When i turn the pedal off, the LED is still on, but glows weakly. My clean guitar comes through tho.
But when i turn it on, a constant high pitch sound is emitted from the pedal.
When i turn the tone knob or any other switch, even on the guitar, the pitch changes.
Do you have maybe an idea, where this is coming from?
alexandre ernandez
Hi!
Have you checked your power supply? High pitch can come from a TC1044 with a bad power supply.
Or please check everything back step by step 🙂
Best regards,
Alex.
Josh
Hello!
I have completed the build and all seems to be working well apart from the tone knob. When it is all the way down and all the way up, it works as it is meant to, but anywhere in between the tone sounds like it is exactly halfway. At 2 its sounds to exact same as if it was at 9. I have checked all components and they appear to be in the correct positions so I am not sure what the issue is.
Other than that the pedal is working well
alexandre ernandez
Hey! Didn’t you’ve shorten the leads of the Tone knob? Or please double check all the components, their values and connection from the Tone section 😉
Khris
I was rushing and had a slight mishap when connecting my pedal for one of the last tests, BEFORE installing the 3PDT switch, and resistor R22 started smoking. I immediately disconnected power, and while R22 had some slight discoloration, I tested it with an Ohmmeter and it read the correct value (10 ohms). I connected everything and ran the sweep and 1kHz tone and everything surprisingly looked ok.
However, after installing the 3PDT switch, the led doesn’t come on. I went back and tested all the test points, and the only one that I couldn’t get a value at was TP7. I tested that resistor (R13, just above the LED) and it showed the correct value (220ohms).
It’s strange that I had a good test signal before installing the 3PDT switch. I also tested the terminals on the 3PDT switch to see if the switch was good, and it seems to be ok.
Any suggestions on how to pinpoint the problem?
Khris
I went ahead and tested the pedal with a guitar anyways, and everything seems to be working correctly, except there is no LED light. Is a blown LED the reason I wouldn’t get a voltage at TP7?
Loick Jouaud
Hi,
Glad the pedal still works well! If you don’t have a value on TP7 then yes it’s coming from the LED. You can test the voltages directly on the LED. You should have one side (anode) which should always be at 9V (or the same value as TP2), and the other side (cathode) which corresponds to TP7. You can also test with an ohmmeter that the anode is connected to TP2 and the cathode to TP7 and R13. The other side of R13 must be connected to pin L- of the footswitch. If everything is good then maybe the LED is burnt out!
Have a nice day!
Khris
Hi Loick. Thanks for the reply. Everything looks good except I don’t get any voltage on the (-) side of the LED. The (+) side was 9v. It appears I have continuity everywhere else, so it sounds like the culprit is the LED?
Any recommendations on a replacement (e.g. from mouser)? Any tips for desoldering the old one and putting on the new one? I guess I’ll be learning surface mount soldering now! 🙂
Loick Jouaud
Hi,
Sorry for the late reply. Desoldering a surface mount component is not easy, the best is to use desoldering wick or pump and slightly lifting the component with pliers or a flathead screwdriver. You can contact us at [email protected] for spare parts.
Have a nice day,
Loick
Russ B
Finished the pedal and all switches and knobs worked for 1 minute, but was slightly noisy when tapping the knobs. Then a kind of splat! noise and now the fuzz is way up, no gain or tone control, no switches work, and the volume knob peaks at 7 then tapers back down. Also when guitar signal volume is low the pedal sputters and then limits out all signal, like a noise gate. Can provide video example if needed. Thank you!
Loick Jouaud
Hi,
Did you do the step by step analysis as recommended in the assembly article? It will be much easier to know where the problem comes from.
If the problem came afterwards, you can try to visualize the signal between each step, to identify which step is the problem.
Have a nice day,
Loick
Russ B
Sorry for the long delay in reply. When testing each test point, none of the readings correspond to the values provided in the pdf. Nor do my readings stay the same. For instance, tp1 readings fluctuate between 47.6, 0.00, and 5.73. This is similar across all test points.
Loick Jouaud
It seems that you have a problem with the power supply. Make sure your external power supply, and the wiring of the power supply connector are ok, TP1 is connected directly to the power supply connector, without going through any component.
Also check the power consumption of the pedal, an abnormally high consumption (more than 100mA) could indicate a short circuit somewhere.
A power supply that is too low can explain the noise gate effect.
Have a nice day,
Loick