V5 Op Amp Big Muff Woes -- No Sustain, Fizzy

[cobascis]

braaandooon, the legend that he is, gave me an op amp big muff that had some issues. I just replaced a few of the capacitors (one was visibly chewy) but it had no effect on the sound. Basically it sounds like its a devi ever pedal or some shit. If you play quietly or roll back volume it won't event make any sounds, play hard and it will sort of sound liked a gated fuzz/od. Actually kind of kool, but not what I want out of a muff such as this muff.

Should I keep going through and replace every old capacitor? Also, the tone bypass has been, well, bypassed. There is also a strange bridge on the pcb, as if the original trace got fucked up so this is bridging it?

Ran out of patience/parts today and want to know if I should track down each cap and replace it, or could it maybe even be the op amp?

Here are some pictures:
https://www.dropbox.com/sh/tguf1azbk2fx ... wfAra?dl=0
Ordered a new multimeter off amazon, and have the rest of the capacitors coming in this week or early next week.

[cobascis]

I ordered all the capacitors I don't have. Any chance it could not be a cap issue?

[Scruffie]

Voltages on the 4558 & 741 and pictures (yours aren't working).

[cobascis]

I have a really shitty possibly non functional multimeter. What setting do I put it on to read voltage? It's on of the spin knob ones with tons of symbols

[cobascis]

Will fix pics tonight

[Scruffie]

Put it on the 20V setting, black to the enclosure, red to probe about.

[cobascis]

Fuck. This piece of shit multimeter just pots constantly changing random numbers on the screen, regardless of setting or whether probes are in. Fuck that. Never get an Excel XL830L

[Scruffie]

Are you in the US? I believe Harbor Freight (I think i'm thinking of the right place) should do a cheapy meter that'll do the job.

Random question... do you think you could weigh the pedal for me? Coincidentally trying to find out the shipping cost for one from a guy in the US to me

[cobascis]

No scale, but I just checked and the large box big muffs are all shipped as 2lbs from amazon.

[cobascis]

Odd that photos don't work -- they work for me. Maybe it's because I'm using dropbox

Here is the folder on DB with pictures:
https://www.dropbox.com/sh/tguf1azbk2fx ... wfAra?dl=0

[cobascis]

Was checking out this page: http://www.geofex.com/fxdebug/bias_prob.htm

It sounds like for sure it is a biasing issue. Got the multimeter and will take a stab at it tonight. How do you fix a biasing issue? Does it imply cold solder joints or bad resistors?

[Scruffie]

Take voltages first, it'll confirm or deny that and then you work on how to fix it, if it is the issue.

[cobascis]

4558 is 8.92
741 is 9.33

[Scruffie]

Need voltages for all 8 pins on each chip

Like so,

[cobascis]

whoops!

741:
1: 8.79
2: 8.37
3: 8.97
4: 9.04
5: 0
6: 8.86
7: 9.39
8: 0

4558:
1: 8.90
2: 8.89
3: 9.25
4: 9.32
5: 8.89
6: 8.89
7: 8.92
8: 9.30