shin ei fuzz wah noise

[pinkjimiphoton]

so i recently decided to mod my venerable 8tr fuzz wah with a switching jack to save the poor batteries from the early demise they always suffered.

this thing had sat in a basement, a dank one, for decades...when i first got it, i cleaned it up and that was that.

well, i did the jack, and noticed this thing was noisey... sounded like bacon frying pretty much.

first thought... electros... this thing is close to 40 years old probably.

so i replaced 'em all with brand new ones. that quieted it down a little, and the fuzz got nicer, but when the wah was on, same crap... crackle pop HISSZZZTTTT TTpop  noise.

ok. so i replaced all the caps with nice new poly ones.

the fuzz now sounds AWESOME, right?

the wah's still making noise. fudge!!

so i thought... carbon comp resistors in tube amps can make this happen...and toyed with the idea of replacing them all. decided...naaaaah. gotta be something else.

so i started doing the usual trouble shooting stuff,  all the voltages seemed pretty good. hmmm.

jack darr time. started physically wiggling components one at a time.

and sure enough, one of the transistors in the wah part of the circuit, when wiggled JUST RIGHT the noise would stop.

so i figure, ok, cold solder joint. i sucked and wicked the hole clean, and used good fresh silver solder. hooked the battery back up.

phuck. same noise, now WORSE.

so i pulled out a bag of 2sc828's i picked up on the bay back when i built the first couple superfuzzes, and replaced the transistor.

about 80% of the noise went away. replacing the second transistor took care of the rest.

from what i've seen on the web, a lot of times peeps reccomend replacing the pot. i can see why, obviously...

noise in wah circuit, you think pot first off.. but that happens mostly when you move the wah, this was just when it was on, and worse in the heel down position, and completely random
and intermittent.

so i figured it probably wasn't the pot.

another thing i'd done before the finger test, and what actually led to finding the transistor that was ailing, was i took the tip of my iron and with the wah plugged in, and guitar up, put it near each component. when i got to the bad component, the noise went down (a thermal problem in the transistor i guess) and it hummed like a sumbitch.

sometimes, it can help ya find problems by doing that. i know the old timers all probably know this stuff, but i hope someone in the future trying to get one of these working can find this info useful.

btw... wasn't 828's in the pedal, i'll have to look but i remember a bunch of 5's in it.

[Mark Hammer]

RG or PRR will likely have something to say about it, but there IS an aging effect on bipolar trannies to, albeit of a different source.  In the case of electros, time dries them out.  In the case of transistors there is some sort of cumulative depletion effect, or whatnot.

I picked up an old Heathkit TA-16 amp a few summers back.  It was bloody noisy as well.  Poking around online for some info about the amp, I came across a post regarding the degradation, over time, of the 2N3391s in the input stage.  So, I replaced them on mine with spanking new 2N5089s, and the noise went away.

[duck_arse]

"loody"? is that a word I should know?

freezer spray, in a can, jimi. works the similar to the iron, but with cold.

[pinkjimiphoton]

hmmm, interesting, thanks mark.

duck_arse... my iron is free. but yah, the cold stuff works too, i've never tried it tho. if i need something cold i usually just chuck it outside this time of year.

[bluebunny]

. . .  i usually just chuck it outside this time of year.

We're all waiting for the PJP "Polar Vortex" pedal anytime soon...   

[pinkjimiphoton]

pink rolls up his sleeves....

[joegagan]

i have found a lot of these older pedals are plagued with transistor noise.  electros, first, then if hiss or oceans or random ticking is there, a trans(plant) almost always solves the issue.

[pinkjimiphoton]

yup. thanks for the endorsement Joe.
first thing i thought after the caps was carbon comp resistors... i mean, hey, it sat in a dank basement for 30 years... but then i thought.. man, i've had this for two years by now, so it's can't be the moisture. and it had to be in the wah... the only things left not replaced were the transformer/inductor, couple resistors, and them two transistors.

startling improvement not only in noise but tone. can see why these were so cool when they were new.

question... would you advise changing out the poly caps too joe? i already did, but now i'm wondering if that was overkill.

[joegagan]

if the poly caps are really cheap and visibly splitting open etc, yes, but i generally leave em.

[pinkjimiphoton]

it had older, dusty looking mustardish very coarse looking caps, some were split.

looks like an electro had exploded in there in the distant past, was covered with that fiber looking stuff inside of caps.

look forward to trying one of your wah pots in this thing.

[joegagan]

I have found lin 50k and other times 100k stock, they always measure linear in the ones i have tested. But i think a log, my normal log would work great. Will double check in the shinei i have here so i know before sending yours.

[pinkjimiphoton]

cool, thanks joe!! looking forward to trying it.. i love the fuzz, but the idea of getting thr full range of the wah is outstanding.