Acetylene Overdrive - squeal / trouble audio tracing past C11

[ThisIsAlec]

Hi team,

I have a non-working acetylene overdrive. The boost circuit is all good, but the main will sometimes squeal, sometimes just sit silent. I did an audio trace and things are fairling quiet coming through Q3 (J113) and I can hear nothing after C10/R16 or at C11. Any idea what's going on or how to isolate the issue? I've tested R16 and C11 and quickly replaced C10 just in case. Not a soldering issue - I checked. Any help is appreciated.

Photo attached in case it helps.

Thanks!

 

[Laundryroom David]

Please post a pic or two of the bottom of the board as well.

How do your voltages look on ic‘s and transistors?

And are you sure of the pinout on Q5? The through-hole J201s from Interfet have a different pin out than the norm.

 

[ThisIsAlec]

Thanks for the quick get back. I attached a picture of the back (feedback welcomed if something looks sloppy).

Voltages on transitors:
Q1 (2N5089): 4.86v (pin 3) 0.68v (pin 2)
Q2 (BS170): 8.6v (pin 1) 1.675v (pin 2)
Q3 (J113): 8.86v (pin 1) 2.41v (pin 2)
Q4 (BS170): 8.75v (pin 1) 1.68v (pin 2)
Q5 (J201): from Linear Integrated Systems, not Interfet
- With bias cranked one way 350mv (pin 1) 169 mv (pin 2)
- With bias cranked the other way 8.8v (pin 1) 300 mv (pin 2)
Q6 (113): 8.86v (pin 1) 2.53v (pin 2)

IC1:
- 1: 4.4
- 2: 4.41
- 3: 4.04
- 4: 0
- 5: 4.4
- 6: 4.4
- 7: 4.4
- 8: 8.8

IC2:
- 1: 4.4
- 2: 4.4
- 3: 4.37
- 4: 0
-5: 4.36
-6: 4.4
-7: 4.4
-8: 8.86

 

[ThisIsAlec]

Hi all, figured it out. I had a couple of caps that were off (C14 and C22), replaced the BS170s that sounded off and Bob's your uncle. This thing is fun! Thanks for the help.

 

[Laundryroom David]

Hi all, figured it out. I had a couple of caps that were off (C14 and C22), replaced the BS170s that sounded off and Bob's your uncle. This thing is fun! Thanks for the help.

Congrats!