cavedweller problem

[medeiros68]

Howdy folks-
this may sound a trivial thing for most here, but it is my first attempt into the PT2399 world. Unsuccessful so far, so I am sure someone here can give me some directions to go.

(1) Project Name: Cavedweller, version 07.23 – Rev.1
(2) General description of the problem: No sound out when on.
(3) Steps that you have taken to try to resolve the issue:
a) checked the parts and values. ok!
b) checked the voltages:
PT 2399:

1 - 5.0V
2 - 2.53V
3 - 0V
4 - 0V
5 (clock out) - I checked with an oscilloscope, and saw a squarewave with a frequency varying in the MHz range (say from 1MHz to 3-4MHz) as I turned the delay pot
6 - about 2.5V, with some component of the clock on top of it.

have not checked the other pins (should I? They all seem output/input rel. to the audio).


(4) List any substitutions you used for parts/values

only changed the 100pF ceramic for a 120pF ceramic.


My main question is:

Q. Could my PT2399 be fried, and if so what is an easy test to check it?


any help is greatly appreciated!
thanks for your time.

[gtr2]

Is your wiring correct?  Photo's may help.  What are your voltages of the TL072?

Josh

[medeiros68]

hi there,
thanks for the fast reply!
cave dweller has no tl072
using the pcb from madbean, so wiring was minimum (and triple checked)...

[jkokura]

I'd be using an audio probe as my primary tool to debug this one. Trace through the schematic and the PCB, and you should be able to find where the signal stops. Do you have signal going into the PT2399? Does it come back out again?

Jacob

[medeiros68]

Thanks Jacob-
sorry about the dumb question - I have been using my guitar as an audio probe, and followed the signal. But it is presumably not the ideal one; what should I use?
thanks!

[medeiros68]

I answered myself with this link:

http://www.diystompboxes.com/pedals/debug.html

does this work?... 

never tried, so I ought to take a look at it.

[jkokura]

It's okay to use the guitar to create signal, but an audio probe should connect to the amplifier. Essentially, it allows you to 'interrupt' the signal and send it to the amplifier wherever you probe.

Yes, you found a thread with some info on how to build a quick and dirty audio probe.

Jacob

[muddyfox]

audioprobe ftw!

Jacob, will your test contraption include an audioprobe and a signal generator of some sort? that'd be nifty, i contemplated building something like that but i never seem to be able to get around actually doing it.


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[jkokura]

Yes, the upcoming Testing Rig PCB will include:

1. Connections for an audio Probe
2. A test signal generator
3. A headphone amp
4. Switches to choose whether any of those three things are on or off, and a bypass switch.

Jacob

[muddyfox]

very cool! thanks for putting this together, my cramped workbench (aka dinner table) will take a lot less tidying up every evening when the spousal unit becomes miffed about the amount of "crap" on it...


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[medeiros68]

Thanks Jacob-
audio probe rules!
I feel stupid for not knowing it, so this was a great deal for me.
I was able to troubleshoot the problem.
Cavedweller working, a bit too dark for my taste, but I will do the C3 mod to see if I can brighten it up.
Also kind of noisy, but excellent experience!

thanks!