White noise/hiss in vintage Univox Micro Fazer

[distorto]

Hello,

I just received this pedal in super clean condition. Everything works great except for the fact that it has a LOT of hiss when switched on. I am in no way turned off by a fair amount of noise (I love p-90s and other vintage single coils) so it is not just a case of me being picky. My questions is this - from looking at the schematic where would be a good place to look for the culprit(s)? Would changing out the electrolytics help? I know if was a cheap Phaser in it's day so maybe that's just how it rolls but I used to have one as a kid and don't recall it hissing like this.

Any insight greatly appreciated.

Chris

univox-microfazer-schematic.pdf

[g1]

That schematic is not working, see attached.
Are the chips socketed? If so that would be the easiest thing to try, swapping in a known good chip.

[distorto]

Hey thanks for that! I didn't notice the schematic didn't take. I doubt the chips are socketed but I'm willing to try that because the unit is unusable as is. Here's a shot of the innards from a Fernandes branded one. There are no sockets in here:

[Mark Hammer]

If it sweeps and produces audible phase-shifting then the chips are clearly "good". That said, the 1458 is not known for its stellare audioiphile quality. I would suggest replacing two of the chips (IC1 and IC2) with TL072 type. You can certainly try one for IC3, but since it also includes the LFO, there is a chance the LO might not behave normally with the TL072. That said, you can certainly install a socket and see if the TL072 behaves better or worse than the 1458.

Note that installing a "true-bypass" switch is contra-indicated here, unless you make some other changes to the circuit to compensate for volume loss.

[distorto]

Mark, Thank you for the info. To be clear, the actual phasing sounds really nice other than the hiss. I have a vintage Small Stone and a 70s MXR Phase 45 to compare it to. The Small Stone has just a hint of background hiss that I probably would not have noticed if I weren't specifically listening for it. The Phase 45 is dead quiet. I would really like to get the hiss dialed back because this phaser has a fairly unique quality under all that hiss. I really don't need true-bypass. I'm happy enough with the bypassed tone. I have one TL072 here now and maybe another or two lurking in the electro junk closet. I'll give it a whirl. Thank you both for your help! - Chris

[distorto]

You guys RULE! I pulled IC1, stuck in a socket, and snapped in the only TL072 I had lying around. Killed nearly all the hiss and the pedal sounds great. Thanks a million - Chris

[Mark Hammer]

Excellent. Nothing succeeds like success!

I love the smell of solder in the morning. It smells like....victory. ( Apocalypse Now - smell of napalm - YouTube )

[g1]

If it sweeps and produces audible phase-shifting then the chips are clearly "good".

I'll assume you meant functional rather than "good", as chips that are defective noise-wise can still work normally in many cases.

Glad to hear the problem is solved.

[Mark Hammer]

Yep, that's exactly what I meant.