The never ender

[ggarms]

Hey guys,


Update on the ZPSDX, or lack of one. I'm still having the same issue, one repeat regardless of the feedback pot setting. Ive changed the feedback pot, r41, and c48. Ive checked all my connections to verify no cold joints/bridges. I'll mention again that this pedal was working great for the first few days, and a component may have been bumped at some point (project is still unboxed). IC's have been checked in other pedals and are all operational.

UPDATE!!!!!!!!!

I realized that when the PATH switch is set in the off position, I am getting absolutely no delay, just my signal. When PATH is on, it goes through each filtering mode correctly, however there is still only one repeat. I'm not that great at deciphering more complicated schems, so what should I be paying attention to on the board? Please help!

[jimilee]

So check your resistors, today I found a broken resistor on an otherwise working effect.it would work sporadically and then stop and then start again. Wiggle those bastards!!! Also (forgive me if you did) but did you post voltages somewhere?

[ggarms]

I compared them to another post i found somewhere and don't remember anything being out of whack. Give me ten minutes and i will have them up so hopefully you can impart some wisdom! thanks.

[jimilee]

It's cool, it's Friday night and I'm headed to dinner now. Weekends are slow around here die troubleshooting, but someone's usually around.

[aballen]

Are you sure the switch is ok?

[ggarms]

Voltages:


TL062

1.  4.6
2. 4.7
3. 4.6
4. 0
5. 4.8
6. 4.7
7.4.7
8. 9.4

TL072

1. 4.7
2. 4.7
3. 4.7
4.0
5. 4.7
6. 4.7
7. 4.7
8. 9.46

TL074

1. 4.7
2. 4.7
3. 4.3
4. 9.45
5. 4.7
6. 4.7
7. 4.7
8. 4.7
9. 4.7
10. 4.7
11. 0
12. 4.7
13. 4.7
14. 4.7

IC3
1. 4.9
2. 2.5
3. 0
4. 0
5. 2.9
6. 2.4
7. 0
8- 0.7V
9. 2.5
10. 2.5
11. 2.5
12. 2.5
13. 2.5
14. 2.4
15. 2.4
16. 2.4

IC2

1. 4.9
2. 2.7
3.0
4.0
5. 2.9
6. 2.4
7. 0
8- 0.6V
9 THROUGH 13- 2.47
14. 2.4
15. 2.4
15. 2.4

[kothoma]

[...]
I'm still having the same issue, one repeat regardless of the feedback pot setting.
[...]
when the PATH switch is set in the off position, I am getting absolutely no delay, just my signal. When PATH is on, it goes through each filtering mode correctly, however there is still only one repeat.

What you call PATH-off is skipping the filter section, right? Here you don't get any delay, only the dry signal?
In the other position, going through the filter section, you get delay, one repeat but no feedback?

So you have at least two problems here.

1) The PATH switch. Looks defect. You shouldn't lose your wet signal altogether here. What happens if you bridge the pins with little wires?

2) The feedback path. Somewhere on the way from the FDBK pot to R41 you lose your delayed signal. A few suggestions:
- It could be a short to ground (check for solder bridges) or a nonconducting component.
- Check D4/D5 (shouldn't short the signal to ground), C48 and R41 (shouldn't block the signal).
- What happens when you engage the SLAM switch?
- Use an audio probe to see where you lose your signal.

[ggarms]

When slam is engaged, nothing happens. I swapped both c48 and r41. Problem persists. I changed the switch, so that issue is fixed, however the single repeat remains. Do my voltages seem ok?

My audio probe results have been inconclusive up to this point. Everywhere I check, I get a single repeat.

[jimilee]

Got any pictures? I'm starting to suspect the 3p4t selector switch next. I'm curious if it's on correctly.

[kothoma]

Got any pictures? I'm starting to suspect the 3p4t selector switch next. I'm curious if it's on correctly.

No, I think we can rule that one out. I understand the single delay gets filtered if the PATH switch is in that position.

[kothoma]

... My audio probe results have been inconclusive up to this point. Everywhere I check, I get a single repeat.

So you get the delayed signal everywhere on the blue path (right to left) below?
If you follow the green path to the final mix point, it somewhere gets lost?

[ggarms]

Jimi, that may not be necessary, like I said before this thing was working beautifully for about a week until I made that physical (height) adjustment to the feedback pot..i'd be glad to if it would help though. To this point, I've made the following changes:

feedback pot now wired w/ regular pot instead of PCB mount (to rule out malfunctioning pot)
c48 swapped
r41 swapped
All IC's checked in other circuits


When I get home from work today I'll double check my probe against your drawing (stupid jobs!) and post results.

[ggarms]

I was excited to come home and check. Your image is correct. Feedback 3 is the last place I am getting delay. C48 and r41 are all white noise, no signal. Does this mean a lifted trace? I've already swapped both components. Thanks so much for the help.

[kothoma]

I was excited to come home and check. Your image is correct. Feedback 3 is the last place I am getting delay. C48 and r41 are all white noise, no signal. Does this mean a lifted trace? I've already swapped both components. Thanks so much for the help.

What about FDBK lug 2? No signal?

Did you check the diodes for continuity? Perhaps one of them conducts (below 0.7V) and your signal goes to ground. Or there is a solder bridge to ground. But in both cases, either engaging the SLAM switch or maxing the FDBK pot would cause your delayed signal to vanish from the mix. (Because then the whole blue path would be grounded, too.)

Check for lifted traces: is there continuity between C48 and R41? Between FDBK 2 and C48?

[ggarms]

There is No signal @ feedback 2. I'll double check continuity and the diodes tonight and make sure there arent any bridges.