SOLVED Duocast not passing audio

innerlight

Active member
Hello all!
I am once again asking for some guidance on an almost functional build (pics attached). This one came together cleanly and I was really confident it’d just work 😭.
I’ve reflowed all solder points and double checked components. I assume the dot on the OC71 is meant to match with the square on the Pcb?
Anyway, LEDs light up, pots make sounds but no signal passes in low or high modes when engaged. Signal passes when not engaged. Curiously, when I switch between 9 and 27v modes I get a pop and a split second of signal.
Do I audio probe next? Please guide me oh community.
 

Attachments

  • 788F185F-D0AF-4AB0-8EFC-F1C27F75C372.jpeg
    788F185F-D0AF-4AB0-8EFC-F1C27F75C372.jpeg
    66.8 KB · Views: 35
  • 3F91A489-5230-42EF-9348-9DAAF399D5F9.jpeg
    3F91A489-5230-42EF-9348-9DAAF399D5F9.jpeg
    55.8 KB · Views: 32
  • 8D85150F-15E5-4881-A973-CE84E12E4DCF.jpeg
    8D85150F-15E5-4881-A973-CE84E12E4DCF.jpeg
    61.1 KB · Views: 37
  • 78EAF332-3B06-48E0-8E63-7989328788AB.jpeg
    78EAF332-3B06-48E0-8E63-7989328788AB.jpeg
    64.1 KB · Views: 37
  • DAFECF05-8EC0-4A5F-BB76-79A4B60F0D59.jpeg
    DAFECF05-8EC0-4A5F-BB76-79A4B60F0D59.jpeg
    80.8 KB · Views: 38
  • 25AF67C1-7BE5-480B-A616-6C61C4570D2F.jpeg
    25AF67C1-7BE5-480B-A616-6C61C4570D2F.jpeg
    77.8 KB · Views: 36
I believe you have the transistor installed backwards.

The dot on an OC71 is usually the collector, the square tab on the PCB footprint indicates the emitter and corresponds to the tab on metal can transistors.
 
  • Like
Reactions: fig
Thanks!
Switched that and now I get functionality with something with high output like a synth. All pots have an effect when used this way. However, signal is verrrrrrry weak with a guitar (this is with all trimmers and pots maxed).
 
Last edited:
I can probe a signal till it hits the TY-141, where it get really really weak. I also replaced the main foot switch just to be sure with no perceptible change.
 
Last edited:
Ok all here is where I’m at everyone.
I can probe audio right through the circuit till I hit R13. It becomes very weak on R14 and I get nothing from the TY-141P on any pin.
I’ve checked those particular resistors (r14/15) and they’re the right values.
Could a trace be damaged/should I try bridging some connections?
I’ve attached the schematic with the dubious area circled.
If anyone would advise me on where I should jump to where I’d be mighty grateful!
This pedal has some very expensive components so I don’t want to say die!
🙏
 

Attachments

  • BEF068C6-D2E4-4543-B25F-CC36B8A30D9B.jpeg
    BEF068C6-D2E4-4543-B25F-CC36B8A30D9B.jpeg
    110.4 KB · Views: 15
Last edited:
R13 is part of your power section. start looking around the section circled in red for sound problems. Is your gain turned all the way down?
 

Attachments

  • 1C5B348E-76DD-41FC-992A-1231C7EED199.jpeg
    1C5B348E-76DD-41FC-992A-1231C7EED199.jpeg
    78.8 KB · Views: 14
Probed that zone, it all seems ok!
Signal is making it to the level two pot but not the output. I ran a wire from the middle leg of the level 2 pot to the out pad on the foot switch Pcb.
Is this bypassing anything?
Now I have signal passing through the pedal, but it’s super weak/quiet and kind of sounds like a gated fuzz. If I strum hard the signal makes it through but soft notes don’t make it.
Any ideas?
 
Ok c11 connects directly with r14. can you confirm r13 is the correct value and if so can you confirm continuity between the two ? Also you try jumping a wire from the c11 to r14. Just make sure they’re both the connecting to the sides their supposed to be according to tho the schematics.
 
Ok c11 connects directly with r14. can you confirm r13 is the correct value and if so can you confirm continuity between the two ? Also you try jumping a wire from the c11 to r14. Just make sure they’re both the connecting to the sides their supposed to be according to tho the schematics.
I’m away from home but I will try tomorrow! Thanks so much, excited to see the outcome
 
Ok! Made a little more progress here.
Ok c11 connects directly with r14. can you confirm r13 is the correct value and if so can you confirm continuity between the two ? Also you try jumping a wire from the c11 to r14. Just make sure they’re both the connecting to the sides their supposed to be according to tho the schematics.
So I checked continuity and values on all of the above. All seemed ok and correct. I then ran a bridge wire between leg 3 of the “level 2” pot to the out of the foot switch (is this bypassing anything??)
It was then sounding super sputtery, so I re-seated the oc71 and switched two of the legs. I’m now getting signal!
Buttttt there are still some issues.

1) both the level 1 and 2 pots don’t have any effect on sound. It seems basically maxed out at all times.
2)the gain pot has verrrry minimal effect on the sound.

Any ideas here? I’m guessing the bridging wire I installed may be in the wrong place?
 
If you have been removing Pots or Components, there is a great possibility that you may have damaged Traces!
Confirm what has been removed & replaced by soldering!
I haven’t removed anything, the only thing I reoriented was the OC71 but that was socketed thankfully!
I did reflow everything, so I may have overheated a trace. But I have no idea where to begin if that’s the case!
 
Ok! Made a little more progress here.

So I checked continuity and values on all of the above. All seemed ok and correct. I then ran a bridge wire between leg 3 of the “level 2” pot to the out of the foot switch (is this bypassing anything??)
It was then sounding super sputtery, so I re-seated the oc71 and switched two of the legs. I’m now getting signal!
Buttttt there are still some issues.

1) both the level 1 and 2 pots don’t have any effect on sound. It seems basically maxed out at all times.
2)the gain pot has verrrry minimal effect on the sound.

Any ideas here? I’m guessing the bridging wire I installed may be in the wrong place?
I’m not sure how you ended up there, I had asked you to try a jumper to a suspected trace that seemed it could be bad based upon you saying to c11 it was fine and r14 it was bad
 
Back
Top