rebote 2.5 voltages...

[dxm1]

at what pin on the pt2399 should i be getting the clean signal?  i audio probed the thing and there is no clean signal at any pin...or delayed for that matter...

It looks like pin 14 of the PT2399 should have the delayed signal. Also, you should hear delay on pin 2 of the op amp.

[oldrocker]

From what I remember no delay just staight guitar from pins 15 and 16.  Delayed signal from pins 12 and 14. But make sure the knobs are set for long delay and full repeats while audio probing.

[roofer1]

okay, there is no delay signal anywhere...there is clean signal on the tl072, but no delay signal anywhere...i tried probing the circuit to try to trace the input to the pt2399, but there are so many branches and splits off that i cant follow it to be able to tell where the input signal should be going into the pt2399.
consequently, i took the chips out of this broken rebote and put them in a new one that i am building and they work perfect...so its not the icss.  completely unrelated to this first rebote, on my second one (using all the same stuff as i can tell) there is a weird pause between when you play a note and when it actually comes out of the circuit...makes playing with it impossible, but other than that...the new circuit is working.
any thoughts on either of these issues???

[dxm1]

Let's see -  the power supply is now workng, and you've verified the opamp and delay chip are alive. So, I would suspect

1) bad offboard wiring (bypass switch), or
2) toasted electrolytic caps.

Do I remember you saying that this pedal worked for a while, then quit working? If so, and you did not change any wiring, that eliminates #1 (unless something is shorted around switch). Check the offboard wiring first.

I see at least three, if not four electros around the delay chip. Going under the assumption that an incorrect power adapter was plugged in, these may have bit the dust. This would be a good time to read through RG's excellent post about troubleshooting reverse power problems.

If it's not either one of these issues, I'm at a loss.

[roofer1]

where'd you find that rg's post on that?

[dxm1]

where'd you find that rg's post on that?

http://www.diystompboxes.com/smfforum/index.php?topic=55003.0

[roofer1]

so we are in agreement that the voltages on the ic's look appropriate?  now its time to change the electrolytic caps...is there a way to test them with a dmm to see if they are fried?

thanks for all the tips and help!

[Samy]

TL072 and 78L05 voltages are correct but something is wrong with PT2399 voltages. Like i said before, you must have around 2,5V from pins 8 to 16.
I think voltage on pin 7 it's too high i believe it must be around 2,5V too but i will check this weekend with my RD 2.5.
Check solder joints close to the PT2399, there are too may solder pins over there and sometimes shorts can happen accidentally.
Use a audio probe to hunt the problem...

[slacker]

You should get some sort of signal on pins 13,14,15 and 16. Pin 14 should have the delayed signal.

[roofer1]

okay, i replaced ALL the electrolytic caps on the board...in addition to the new 5v reg that i did yesterday...in about 10 minutes i'll post new voltage measurements to see if anything dramatic has changed...
its playing clean signal at pins 1 and 7 on the TL072 and at pin 15 on the PT2399...
give me a second to measure again...

word.

[roofer1]

Battery = 8.29

TL072
1= 4.12
2= 4.12
3= 4.12
4= 1.8 Mv
5= 4.02
6= 4.13
7= 4.13
8= same as battery

7085
in= same as battery
grd= 0
out= 4.97

PT2399
1= 4.97
2= 2.47
3= 2.5
4= 2.5
5= 4.95
6= 2.47
7= a rapidly descending Mv (from 300 down to 0)
8= 4.55
9= 2.47
10= 2.47
11= 2.47
12= 2.47
13= 2.47
14= 2.47
15= 2.47
16= 2.47

any redflags???  thanks a ton...this rebote IS going to work.  its analog, its electro-mechanical, it should be easy to fix...

[oldrocker]

Well pin 4 of both the TL072 and the PT2399 should be 0 volts and grounded.  Why there seems to be residual voltage on the op amp and over 2 volts on pin 4 of the delay chip means a possible solder bride exists.  A good light with magnifying glass would be a useful.  And maybe re-soldering any possible cold joints.

[roofer1]

when i measure the ground circuit there are a couple of mV showing up instead of zero...is this typical of a circuit??

[oldrocker]

No not really.   There should be absolutely no voltage I would think.  Use the continuity setting on your meter and put one lead on the sleeve either on the input or output jack.   Then look at the schem and check the circuit where the grounds should be.  You should have continuity at all the ground points.  It might be a solder bridge somewhere but first see if all of the grounds are connected together like they should and go from there.

[roofer1]

okay i got that...there seems to be clean signal going into the chip, but no delay coming out at the out pins...i've checked continuity between the components around the pt2399 out pins and things seem to be good there...i have tried other known chips too with no success...

[roofer1]

i've got clean at pin 15, not at 16.  i've got delay at 12, 13 or 14 where according to the schem, there should be delay...

[slacker]

Your PT2399 voltages are still dodgy. You should have 0 volts on pins 3 and 4, pin 5 on mine has about 2.9 volts and 7 and 8 have about 0.6 volts. If you're using the tonepad layout I can't really see how you can have 2.5 volts on pins 3 and 4 because they're on the same trace as pin 2 of the 7085 and that has 0 volts on it.
I'd double check round pins 3,4 and 5 for solder bridges.

[oldrocker]

Pin 5 should have no connection to anything.  It's not used but may have voltage readings.  As for the other pin voltages I would look for solder bridges also.