Stone Fuzz pic's

[dansamp]

Ok,
a while back I had posted regading a Roger Mayer Stone Fuzz I had purchased
in trying to debug it I managed to fry one of the tranny's
you guys had asked for pics but I had lost my camera
well I finally found it   !!!
so let's see if I can post some pics :








hope that worked

Dan...........

[dansamp]

ok let's see if I can get them bigger








let's try that

Dan....

[trevize]

seems like they have a 47ohm or 470ohm reducing the input limit the fuzz, like rolling back a bit the volume on the guitar.

could you post voltage readings?

did you check for continuity between the switch and the input capacitor? check the first resistor solderings, it seems critical from the pictures.

[petemoore]

  HD Wiring/Construction/'hold here' wires hot glued by switch [I reason the switch vibrates...]looks real good.
  Thin spread out traces [I see and have no basis for opinion on, other than they carry the current...].
  2 transistors, and I see a 100k hooked between an E and a B...must be "FF" type Stone Fuzz...I'd prefer sockets I think...but would just whip up another board for testing other transistors/etc. in the SF circuit topology.
  Cool !!! Thanks for going to the trouble to share !!!
  All I can offer is use the basic debugging techniques...
 

[dansamp]

the resistor from the switch to the board is a 4.7
the 2.2uf cap looks fine
the first transistor reads -4.30 c
                                    -1.368 b
                                    -.744  e    (taking the readings top to bottom, I hope I have marked the correctly


second transistor reads -1.369 c
                                   -.605 b
                                    .000 e 

[dansamp]

correction the resistor from the switch to the board is a 4.7k

Dan.........

[tcobretti]

Thanks very, very much for posting those.  I've been trying to get some info on that circuit for a while now!

Does it oscillate with both knobs dimed?

[dansamp]

no it does not

[tcobretti]

One last question:  there are different types of BC559s - a,b, and c.  Do you know which it is?

Again, thanks so much for these pics; I've built a few Mayer pedals and I've been really curious about this one.

BTW, it uses the exact same PCB as my RM Classic Fuzz.  It' s just populated with a few different critical components.

[dansamp]

no I can't read anything else on the transistors
it reads   559      and below that
              PH 8 1

[tcobretti]

Thanks for checking, I'll research it and post it if I figure it out.

[Stephen]

Should be simple to check grounds, connectors , batt voltage to grounds ,trans votages, jump a wire straight to output from the input follow the sounds ,see where it ends , as long as the the above was OK ...grounds and batt votege usually!!!

[tcobretti]

My best guess is that it's a Philips brand BC559, and they only make the C version which has 420-800 hfe.

I'm likely the only person who cares anyway.

For everybody beside Dansamp: there was a thread several months ago where Dansamp and petemoore figured out what was wrong with the pedal.  Dansamp is just posting gut pics for us now.

Thanks again, D.

[Pedal love]

My best guess is that it's a Philips brand BC559, and they only make the C version which has 420-800 hfe.

I think you are right.

I don't want to be a downer, but you really must test transistors of a new unaltered model. These types of fuzzes can
have a wide variation of sound, unless the gains of the actual transistors are known. They are silicon transistors, so I'm sure there is probably no real leakage.pl

[tcobretti]

I've breadboarded this pedal tonight, and I can't get it to bias.  The big thing is that I don't have a trimpot for Q1; I've been plugging in resistors trying to get close. ( I've decided my revised Socket Face layout will certainly include a trimpot for Q1)

However, tinkering with the bias resistors I did manage to get a killer fuzz using MPSA18s, which have a hfe similar to the BC559s (the 18s I used both were around 620 hfe).  It's a lot like a Ge FF, but with more gain and thicker sounding.  With the fuzz knob dimed it's actually too much fuzz, but at about 8 it is perfect: tons of fuzz, but still cleans up very nicely with the guitar's volume knob.  Probly the best sounding Si FF I've heard.  That said, I haven't had the chance to crank it and see how it sounds loud.  Volume can change everything.

[dansamp]

do you think I should sub a mpsa18 for my first tranny instead of that NTE I have in there now

I have a couple I just pulled out of my reissue Vox wah 'cause i put some BC109 's in there

Dan...............

[petemoore]

  Dansamp I'd read the GEO FF article and how to pick transistors for FF...lower gain for Q1 [say 70-110hfe] and Q2 @ 110+  the 'co-equate'...but Q1 as lower gain than Q2...
 Or go for mongo gain and stick med to high gainers in...it won't clean up the same @ guitar volume.
  Rebias after Q swaps [re-voice?]
   

[tcobretti]

do you think I should sub a mpsa18 for my first tranny instead of that NTE I have in there now

I have a couple I just pulled out of my reissue Vox wah 'cause i put some BC109 's in there

Dan...............

The MPSA18 won't work in the your Stone Fuzz cause it's an NPN Transistor.  It worked in mine cause I built it to be NPN.  If I were you, I'd order a handful of BC559Cs the next time I ordered from Mouser, I'd  measure their HFEs with my multimeter to pick out the one I wanted.

But if you like the pedal the way it is, don't bother.  Just rock!


Pete:  what's sorta unique about this pedal is that it uses high gain transistors that are not commonly used in Si FF.

[Gus]

you can drop all kind of gains in this

http://www.diystompboxes.com/pedals/gusFuzzFace.gif

been in schematics for years