help with roger mayer fuzz

[dansamp]

Just picked up a Roger Mayer Stone Fuzz

used it doesn't sound right very splatty when turned all the way up fuzz low no sound at all

I bought it in the hopes of just being able to adjust the bias
I can't get it to bias at -4.5 volts
the trim pot goes from -1.5 -2.5 range then jumps up to battery voltage so I figured the trim pot was bad
I played around with different settings and discovered that the collector voltage changes with the fuzz control

so I was trying to readjust the bias and ended up touching the leads to the emitter and I smoked one of the transistors

the markings on the transistor read C559 and below that PH 81

does any one know what these area

they look like silicone but it is negative voltage

hope someone can help


thanks

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

[nightingale]

Dan,
Could ytou check and see what the input,  and output cap values are in your stone fuzz? I am dying to know.
Thanks in advance,
ry

[dansamp]

the input is a 2.2uf electroyltic
I will check on the output

I am going to copy the circuit and make a layout for it soon

I bought it at G.C. as a non working pedal and I have 30 days to return it

I found that it has BC559 slilicon pnp transistors and these are very high gain
maybe that is why the collector voltage was so low
either way I don't think it was working right
before I smoked the first tranny I had it working but it would only work with the fuzz at about 10:00 o'clock and up and only in certain positions

the volume pot is a 47k log A and the fuzz is a 2.2k lin (IIRC)


anyway I need to find a replacement tranny

I subbed a Ge OC44 in there temporarily and it works the same

I subbed a 1k reverse audio pot that I got from small bear for the fuzz pot but it has very little output that way

[nightingale]

Dan,
Its basically a high gain SI fuzzface. The magic is that is that there are no oscillations, or RF interference. I bought some BC559's from mouser with the intent to clone a the stone fuzz, but I ran into heavy oscillation problems with those tranny's. I took a look under the hood of a friends stone fuzz, and I thought the input cap was quite a bit  smaller? I will look back over my notes, when I get home.

thanks again,
ry

[dansamp]

ok got it fixed .............
but I am not sure I like how it sounds 
it sounds best biased at about 1.2 volts

is this correct

by the way someone was in there before and switched th to wires going to the fuzz control pot
it would only work at 2/3 of the fuzz pot up or more now it works with the fuzz pot at all levels but I don't think I like the way it sounds

[petemoore]

  Someone said it's a FF so I'm guessing you're refering to voltage on Q2's collector:
it sounds best biased at about 1.2 volts
Which doens't sound right...what is the supply voltage?

[tcobretti]

You would be doing the community a service by posting either a schem or some good pics of the guts with values for the caps.  Mayer pedals are favorites for many of us around here.  As well, allowing us to see how it is wired might help us diagnose your problem.

[dansamp]

I would love to but I lost my digi camera

I will be hand drawing out the layout


yes I am refering to Qd on the bias question


Dan..........

[dansamp]

sorry for the typo I meant Q2

[Gus]

could it be a 2SC559?   Often the 2S is left off.

http://www.datasheets.org.uk/specsheet.php?part=2SC559

2SC559s are npn so If the circuit is realy a - supply they don't make sense

but

this is a non working effect so you don't know what was done to it before you bought it I would guess.

How many parts and what values are they?  This might help out.

A 2.2K fuzz pot should bias it fine.  need collector Rs and feedback R 47K or 100K?

[dansamp]

I have it working now everything was stock in the circuit except somebody had switched the two wires going to the fuzz pot
so when the fuzz knob was turned down you would loose the bias voltage to Q2
it ended up being a variable bias knob

now I have it wired correctly after checking geofex fuzzface article
I just am not sure I like the sound

the only markings on the transistors are C559 and below that PH 81

the transistors were correct PNP and it is a positive ground circuit

I just stupidly smoked one of the transistors by not being careful

I bought a NTE159 tranny to use as Q1


the parts are as follows   4.7k resistor from switch to circuit board
2.2uf input cap to a 100k resistor to base of Q2 and the other end to collector of Q1 a 47k trim pot connected to Q1 base and Q2 collector

getting negative voltage with a 10k resistor the other end connected to another 10k resistor feeding Q1 emitter
output is 10n small rectangular cap also there is a cap under the board connected to the trim pot
volume pot is 47k Log B  and teh fuzz pot is a 2.2k Lin A

my question is what should the bias be at collector of Q2
it sounds the best with -1.28 volts anything above -2.5 volts gets very splatty and anything less has no gain

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


and by the way it is not true bypass

[dansamp]

ok here is the latest

I was wondering why there would be a plastic washer on the fuzz pot and the pot ground lug was soldered to the case of the pot
how could it go to ground

so I removed the plastic washer and biased Q2 by ear
I now I am thinking this pedal is going to be a keeper !!!!!!

maybe I will get some matched tranny's from small bear and hang on to this

I bought it at G.C. and they gave me 30 days to return it

but now I am not so sure I should return it

I am just bummed I damaged the original tranny

or maybe I should just clone it then return it 

any thoughts

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

[tcobretti]

I would certainly keep a Mayer pedal I managed to find used.  You don't think you can find an BC559 to replace the burnt one?

[nightingale]

Dan,
Are you in the states? Those tranny's are available at: mouser.com, and futurlec for 10 cents a pop.
I would hang onto it man, those enclosures not only look good, but hey are so durable. Plus RM's layout that he uses for the stone fuzz is not prone to any sort of oscillations with those high gain SI trannys. I think the data sheet of the BC559 lists the Hfe around 800.  I have had a hard time finding a PCB that I can use tranny's with no squealing at the higher fuzz settings.

be well,
ry

[dansamp]

Ok cool

I checked on mouser on line and could not find the BC559
I still am wondering about the bias voltage though

[tcobretti]

Here ya go.

http://www.mouser.com/index.cfm?&handler=data.listcategory&D=*bc559*&terms=bc559&Ntt=*bc559*&Dk=1&Ns=SField&N=0&crc=true

[dansamp]

thanks man

you guys   ROCK!!!!!!!!!!!!!!!!!

still looking for bias specs though

guess if it sounds good maybe it's not so important ??

[nightingale]

Dan,
You were right about the input cap 2.2uf.  I have a friend who live down the road that has the whole rocket series. I will try to get you some voltages later today. That way you can restore it to original RM specs.

I will get back to you later,
ry

[formerMember1]

nightingale i sent you a PM...

also, why did you say

Plus RM's layout that he uses for the stone fuzz is not prone to any sort of oscillations with those high gain SI trannys.

do you mean board layout? or physical wire routing?

[dansamp]

Nightingale  ,
thanks a lot

that would really help out

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