Super Fuzz transistor pinout question

[limit6]

Derringer, are you saying that C1 and C16 are wrong on the vero?  Do both negative bands not face down like in the picture?  I'm confused by your wording.

[Derringer]

yep, that's what I'm seeing


C16 should be an easy cap to figure since it's the power decoupling cap. It has the "band" side (negative) on ground.

C1 should therefore have its "band" side facing the guitar input and its positive side facing the base of the transistor.
In this picture it does not.

so if i were to try a build from this layout, I'd get a schematic handy and triple check every connection and orientation.


/derp - fixed, thanks PRR

[PRR]

> C1 should be an easy cap to figure since it's the power decoupling cap. It has the "band" side (negative) on ground.
> C16 should therefore have its "band" side facing the guitar input and its positive side facing the base of the transistor.

C16 is power filter.

The dark-side is the negative side.

Caps are marked for the negative leg:



C1 is the input cap.

Ah, yes it does appear to be wrong-way. (As you say: Input is nominal zero V DC, we expect Q1's legs to be positive, the + of C1 goes to Q1 and the - of C1 goes to input jack; that's not what's drawn.)

You "can" verify cap polarity, in most circuits, by building it without the caps, poking the cap-holes with volt meter, noting polarity, and stuffing the caps that way. But for more than a few caps, that's tedious and very error-prone; here we have 13.

[pinkjimiphoton]

FWIW, i DID build mike livesley's layout exactly as drawn, and it works great.
i don't have it any more, but it's in the superfuzz shootout on my youtube

[limit6]

I contacted Mike himself and noted C16 and C1, sent him the picture, and he said

"C1/C16 are fine unless you're reading the schematic/layout wrong.

shaded end = negative = cathode."

He then went on to apologize for the layout being so big. 

[nocentelli]

http://experimentalistsanonymous.com/diy/Schematics/Fuzz%20and%20Fuzzy%20Noisemakers/Univox%20Superfuzz.gif

The schematic posted by digi2t above is the only one with the input cap polarity marked, and whatever Mike says (love his vero layouts, btw - his DLS was like the second pedal i ever built), the input cap on that layout is reversed to how it is designated on the schem: The banded end should connect with the input. It will work as drawn, but that's not how it should be.

[limit6]

I'm gonna reverse my C1 asap.

[limit6]

Thank you thank you

[pinkjimiphoton]

yikes, too late to fix mine. 

i'd imagine the only real issue may be having the outside of the cap acting like an antennae by not being connected to ground, right?

[nocentelli]

yikes, too late to fix mine. 

i'd imagine the only real issue may be having the outside of the cap acting like an antennae by not being connected to ground, right?

I'm not really sure about the potential problems, i know reverse voltage can damage polarised electro's but i don't know whether the voltage here would be enough to cause issues.

[pinkjimiphoton]

i may be wrong, but i think since caps are "open doors" to ac, the only real issue is the outside wrap of an electro is supposed to connect to ground to "shield" the capacitor. i don't think the voltage coming from a guitar could damage it, but maybe after another driver or effect if it's putting out too much power.
still tho, i don't think the ac part is the thing, i think it's whether it can stand up to dc voltage that's more important. if a shield is connected to + and the input is connected to ground, i'd think it would maybe act more like an antennae and pick up noise, instead of sending it to ground.

but remember... i am farrrrrrrrrrrrrrrrrrrrrrrrrrrrr from an ee, and have only rudimentary understanding of this stuff still. at this point i'm kinda thinking of components and networks and stuff almost like effect pedals... to get the desired sound ya hear in your head, by combining whatever effects/components are necessary to find that sound.
like.. certain values of caps "sound" different when ya put audio thru them.. stupid stuff like that, if that makes any kinda sense.

(like much of my life, i stumble upon this brave new world just as it all becomes obsolete     )

[PRR]

> outside of the cap acting like an antennae

No.

An electrolytic cap does NOT like reverse voltage.

It turns into a short.

If the power bypass cap is reversed, acts short, it sucks ALL the power out of the power supply. It typically blows-up. Maybe with a small fart, but I have seen a mini mushroom cloud and a pound of foil-paper exploded inside an amplifer (yuck).

If the input cap acts short: not enough power here to cause explosion. Instead the circuit just won't work right. Q1 Base near ground, instead of up a volt or so, meaning Q1 is cut-off. (Maybe only when you have something plugged into the input?)

[limit6]

All built!     Not really working well though.  One of the tone switch positions doesn't work and passes clean audio as if the effect were bypassed.  The other has the effect but it sounds like the clean signal is just as loud coming through as the effect.  Any ideas?  Common troubleshoot?

[limit6]

Ugh... dumb.  I wired the tone switch wrong.  Still pretty clean sounding though.  I'm using 828 transistors that have a Q on them (only one had an R).  All measured between 140-215 hfe.  I just picked all the lowest gain transistors and threw them in, and put two matching 180 hfe transistors in Q4 and Q5.  I'm guessing one of two things could be the culprit, the diodes or the transistors.  I'm using OA90 diodes.  Probably time to socket the transistors and see if I can pump more fuzz into this circuit?

[Derringer]

I'm guessing one of two things could be the culprit

actually, the permutations of things that could be wrong are way greater than just two
the gains of your transistors are fine. This circuit will make gobs of fuzz with a very wide range of transistor gains

Can you post the voltages of the transistors in in the circuit?
Follow this format:
Q1
C =
B =
E =

Q2
C=
B=
E=

...

then someone will more likely be able to assist

[limit6]

I'll run a search on how to measure transistor voltage and report back with the readings.  I assume I need to remove the transistors to do this, yes?

[limit6]

Found the stickies.  I'll measure all transistors and diodes and report back.  Thanks everyone for all your help.