Please Help! PT-80

[muehring56]

Okay, I got my PT-80 all together using the layout from ustomp.com.  It's working, but the effect is really faint.  If I turn the volume down or the delay time or repeats up I lose the echo.  Plus when there is an echo it's quiet and only repeats once.  There is also a slight hum when the effect is on.  This is my first effect that hasn't worked first try so I don't have much experience in troubleshooting.  If anyone has ideas of where I should look I'd appreciate it.  

The only thing I wasn't sure of when putting it together was wiring the 3pdt.  I wired it like this effect:

http://www.diystompboxes.com/beginner/circswled.jpg , but instead of wiring the middle bottom lug to the 9v on the board I wired it to the led on the board.  It seems to do what I want this way, but maybe I'm missing something.

Any help is appreciated.  Thanks!

[Aharon]

Complicated project for a first time builder!
Anyway,first I would disconnect the bypass and try just the effect.Also check for solder blobs and shorts.You can also hold the PCB to the light to check for those.
Aharon

[muehring56]

bump

[Chico]

First thing that I would do is to make sure that all of your voltages are correct.  Do you have regulated 12 volt and 5 volt power?  Follow each power trace and ground trace.  Do the voltages look ok on the IC chips.

At the same time, confirm that the chips are oriented correctly.  Confirm that the transistor is oriented correctly by verifying with the correct data sheet.  I have had more than one circuit not work only to find out that I stuck the transistors in backwards.

Speaking of power, I think some folks here have had success running this pedal off a single 9v battery.  In my build, I have a finicky compandor chip that does not like low voltages.  I found that I could only get reliable performance by using a power adaptor.

Assuming that your voltages look good, build (if you haven't already) an audio probe and start tracing the circuit.

My pedal is extremely quiet and does not hum.   That may be a clue to your problem.

Best of luck

Tom

[muehring56]

Thanks for the responses.  I'm going to build the audio probe in the next couple of days.  I saw it mentioned on here, but didn't know exactly what it was.  Thanks for pointing me in that direction Chico.

This isn't my first build, but my first four effects went together without problems so I haven't had to look into debugging.  I haven't tested the ICs yet, but I know they are in correctly.  

The pcb I used only uses a 5 volt regulator (I believe) and runs on 9-12 volts.  I'm using a 12 adapter, which was the recommended supply by ustomp.

I'm going to try your suggestions and hopefully I can get this working soon.