[Billy]

Yes it’s a PNP transistor nothing fancy it’s used in the octave stage

It’s the Tim Escobedo pushme pullyou circuit

Some info here

https://www.reddit.com/r/diypedals/s/TF2h3NawAo

 

 

[Billy]

510 is the code for a 51pf capacitor

The first 2 digits are significant numbers the 3rd digit the number of zeros so 51 with no zeros

[Billy]

Yes you only need one clr if you’re using the 3PDT pcb solder it on there and ignore the main pcb clr R19

Just be aware 1K8 will give you a pretty bright LED if you don’t want a bright LED just increase its value

I personally like a pretty dull LED and use a 10K clr with a standard LED

 

 

[Billy]

Most are here link near the bottom of the guides page

You’ll need to register a free account to download

https://www.yumpu.com/en/guitarpcb.com

Your image is the 3PDT buffer board

 

[Billy]

What I’d suggest you do is build a simple audio probe to check signal is actually getting into the circuit

With no effect or bypass signal it sounds like it could be something as simple as a poor connection or solder joint stopping audio either getting in or between each circuit or a faulty switch or jack etc

All you need is a mono jack a couple of bits of wire a 100n to 1u film or ceramic cap and a small croc clip or something to connect to ground see below image

Connect one leg of your capacitor to the tip lug with a wire to the other cap leg and something robust like a discarded diode or electrolytic cap pin to the wire end for your probe connect your other wire to the jack ground lug with a clip on the wire end to connect to a ground point

Ignore the first few building a probe pages in this PDF and read from page 6 using your probe

https://drive.google.com/file/d/1T9OsJ0riQhm1QFWPfNQ5q5guikuFKDRN/view?usp=drivesdk

The 3 circuits are connected in series like this so your signal would go from in jack to in on the first circuit switched to effects mode middle common row connected to top row it goes from in to snd1 into and through the circuit to rtn1 and so on

Middle common row connected to bottom row as you can see it goes along the trace to out bypassing the circuit and to in of the 2nd circuit

 

 

[Billy]

It could be a few things causing it power supply etc if you’ve used sockets make sure your transistors are nice and securely locked in

You can put your finger on each transistor to see if the oscillation stops

 

 

 

[Billy]

Check C9 is the correct value and has good solder joints

I can’t see if your pots have plastic covers on them if not check that the bare metal rear of the pots isn’t touching any solder joints especially the tone pot if that’s shorting to anything it’ll affect tone and volume

Try adding a jumper between 3PDT lug 1 top left and lug 6 bottom middle

Now and again you’ll get builds that have switch pop and I’ve found this helps even though this circuit has a pulldown resistor R1 so perhaps reflow R1 first then try the jumper

 

 

 

[Billy]

All your component values and orientation look correct

The germanium diode D1 I’m not sure some Russian dides have the stripes on the anode + side

You can easily check it with your meters diode test place your black probe on the white striped side red on the other side if you get a forward voltage reading it’s correctly orientated

You shouldn’t get any scratching sounds on your volume pot that’s usually an indication of DC leaking into the audio path check all your capacitors have good solder joints

 

[Billy]

Socket those capacitors and try different values

[Billy]

Looks like your in jack ground connection is going to the pcb tip pad try swapping your purple and black wires around on the pcb in pads

[Billy]

From your description with both circuits working independently it does sound like an order switching problem one switch position works the other appears to not work why idk

Continuity checking all 3 switch connections will hopefully reveal the answer

 

[Billy]

I’ve been building for 20 years and still make mistakes, it’s easily done

Continuity check your order switch connects as it should in both positions ie with fx1 first then fx2

[Billy]

All your component values  and orientation that I can see look correct I can’t see R15, 16 and 17 completely

As Barry said some of your joints do look potentially dry it’s difficult to tell with the reflection

A3 on the order switch looks like it may have a poor connection

[Billy]

Yes it’s definitely worth biasing the bottom drain pin to different voltages to see if you can get a sound you’re happy with I generally start around 4.5v and increase bias voltage

Are your pickups active or passive

Where did you get your transistors although J113s are still available in through hole package there are a lot of fake FETs around

 

[Billy]

I can’t quite see the 4th multiplier band on R20 the bands should be brown green black red brown 15K

 

[Billy]

Yes you would solder TR1 to both the pcb and switch

From the schematic when you press the switch it looks like you bypass the trimmer and pot so the only resistance in the feedback loop would be RA

The idea being you want it to give you a momentary blast of infinite repeats when you press the switch without having to alter the repeats pot but you’d also want it work normally when the switch isn’t pressed

So your RA value needs to be small enough to work in both scenarios

The way I would do it is socket RA and try different values set repeats to max then adjust TR1 until you get infinite repeats for normal use you should then get exactly the same when you press the switch with the repeats pot in any position

If you don’t there must be a mistake elsewhere

 

 

 

[Billy]

 

Here’s the V4 build doc

https://drive.google.com/file/d/1ElKNvJISHXxjPiFddrfmgE2DuW3DaZvN/view?usp=drivesdk

[Author]

Posts