Bellum Fuzz MkII not working

[apc42069]

Well this was a surprise!

Nothing complicated whatsoever in the build.. thought I was breezing right through it. Alas.

At first I thought there was no output & suspected a mystery ground somewhere.. dimed every knob & the volume on my amp, and heard a little somethin somethin.

Some kind of very quiet frequency is being produced from the amp. Almost sounds like an oscillation? A "warble" of sorts. When I touch any of the pots there is a change in output. It makes that familiar hum/buzz sound - like if your guitar cable is connected to the amp, but the other end is flapping in the breeze.

I know 2N5088s are stable, and all of these tested with similar hFE ~500. The 1n34As are matched in the low 3s. I'm testing it on the auditorium platform.

Hoping someone with eagle eyes, or common sense, or incredible knowledge can spot something here & help me out..

Thanks in advance for any and all assistance-

 

[Cybercow]

Can't tell from the photos, but oftentimes, the leads on socketed TO-92 and other components need to be "wrinkled" at the ends so they fit snuggly into their sockets.



Short of that, you may need to conduct an audio trace session.

 

[apc42069]

Can't tell from the photos, but oftentimes, the leads on socketed TO-92 and other components need to be "wrinkled" at the ends so they fit snuggly into their sockets.

View attachment 35846

Short of that, you may need to conduct an audio trace session.

thanks.

the socketed connections seem to be fine.

i'm either shit with the audio probe, or it's harder than it "should" be.

I get no output at either pad of C3, but i DO get signal beyond it. I replaced the cap to be safe, with no change to the probe results.

I get no signal at either pad of C7, and DO NOT get signal beyond it, so assuming my issue is there. D1, D2, R16, and Q3 all pass signal. I replaced C7, the joints look fine to my eye.

Is the board cooked somehow? Should I try and somehow bypass that capacitor?

Thanks again for taking a look.

 

[Coda]

Are the diodes correctly oriented?

 

[Cybercow]

Dbl-check the value of R6. It should be 390R (not K). By the color bands, R6 appears to be a 190K. That will shut down that first tranny.

 

[apc42069]

Dbl-check the value of R6. It should be 390R (not K). By the color bands, R6 appears to be a 190K. That will shut down that first tranny.

nailed it! R18 too...

really a win-win, because now I know what happened to all my 390Ks lol - running 3x 130s in series for a recent Aphrodite build only happened after a solid hour of tearing my bench apart "i KNOW i ordered 390K...but, but where??????"

labeled incorrectly, that's where.

THANK YOU

 

[Cybercow]

Glad you found the other one too. (I stopped after finding the first incorrect value.)