SOLVED No Dry Signal When Engaged (Dark Rift Delay)

[bschobs]

If you were to troubleshoot a pedal that has only a wet signal when engaged, are there some common places to start? Dry signal is normal when in bypass. This one happens to be a Dark Rift Delay. When engaged I am able to adjust the mix and hear the wet signal but the dry doesn't come through at all.

I'm expecting to need to go through all of the troubleshooting steps but thought I would throw it out there in case there are some things to try first that I am missing.


Thanks!

 

[Nostradoomus]

Post pictures regardless

 

[bschobs]

Hyg sorry about that

 

[Nostradoomus]

Is your 78L05 oriented properly? Your wiring looks good. What voltage are you getting at Pin 1 of the PT2399?

 

[bschobs]

The 78L05 was oriented incorrectly. I corrected this but get the exact same results.

I'm getting 5.02 at pin 1 of the PT2399.

 

[Nostradoomus]

Also double check your values in this area and around it, this is your dry path.

 

[bschobs]

R8 - 2.52

C7 - 2.47 on one lead and 0 on the other. This didn't seem right so I replaced it with another 1u MLCC, no change. I did this from the top w/out taking the board out so if this is the obvious issue I'll just have to pull everything out.

B50K Repeats Pot - 0 on all leads

 

[Nostradoomus]

I mean check to make sure they are the correct value, don’t go tearing anything out yet. Visual inspection is your best tool.

 

[bschobs]

I'm pretty much a noob. Baffled at why it would have voltage on one lead and not the other. What might cause that?

Double checked the value and it's 1u which is what the recipe calls for.

 

[Nostradoomus]

Best take it out of the case and check for cold solder joints

 

[bschobs]

Will do. Gonna be tomorrow. Appreciate the advice and will post findings

 

[bschobs]

Took it apart last night. Re-soldered some things. Did some stuff. Put it back together. Same result.

 

[Nostradoomus]

Time for the audio probe!

 

[bschobs]

Audio probe not my favorite but dammit want to get this ting goin. Maybe this indicates a bad joint or a few of them? My soldering isn't the best but double checked some things last night when I had it apart and didn't see anything egregious. I'm fairly certain there are no solder bridges.

Trying to make sense of this... here are my audio probe findings so far. Not what I expected as I seem to be finding wet signal along what you had identified as the dry path ^

IC1 - Hearing dry signal on the left pins, wet signal on the right
R7 - Nothing from the left, dry signal only from the right
R8 - Wet signal only from the left lead, nothing from the right lead
R9 - Both wet and dry signal from the left lead, nothing from the right lead
R10 - Wet only on both leads
C7 / D2 / D3 - Wet signal only
Repeats POT - 1 - no signal 2 - softer wet signal 3 - louder wet signal

 

[Nostradoomus]

Is R4 47K? It’s the only one I can’t see the value of, shadow in the picture!

 

[bschobs]

Indeed it is

 

[Mcknib]

What you getting at R18

 

[bschobs]

R18 - Dry signal only

 

[Mcknib]

I'm not familiar with this particular circuit but some PT2399 delay circuits mix the wet and dry signal looking at this I thought it would be IC1.2 with the delayed signal coming in via the mix pot

But you say on the right side pins 5,6,7 you get wet only I expected you to get dry going in at pin 5 and wet at 6

What do you get with mix all the way down

 

[bschobs]

On the TL072 I can hear dry signal on the pins 1-3, and then wet on 6 and 7. No signal on pin 5.

... and with the mix all the way down I get nothing at pin 6 or 7