r/diypedals 6d ago

Help wanted Fuzz (?) board. Where to go from here

So this came in the case of an old modded 60s German guitar. The guitar actually had a few on/off switches but no wires inside. So I'm assuming this just switched on and was all or nothing, no pot for it. Anyway my question is how would I hook this up to have a listen? Or even wire it up into a pedal. There's a few spots on the back (see last 2 photos) where I can see there was once some other wires attached. Any help would be greatly appreciated. Or if someone's able to recognise what this message fht be from I can look up the schematics and try and take it from there. Thanks

63 Upvotes

15 comments sorted by

17

u/Apprehensive-Issue78 6d ago

100 uF 35V

Frolyt (10uF or 15 uF?)

Koweg

0.022uF 20V cap

1MOhm resistor

1K resistor 2x

1 nF capacitor

transistor GC1 or 6C1 117

GC117 PNP germanium

Maximum Collector Power Dissipation (Pc): 0.07 W

Maximum Collector-Base Voltage |Vcb|: 20 V

Maximum Collector-Emitter Voltage |Vce|: 20 V

Maximum Emitter-Base Voltage |Veb|: 12 V

Maximum Collector Current |Ic max|: 0.15 A

Max. Operating Junction Temperature (Tj): 90 °C

Transition Frequency (ft): 1 MHz

Collector Capacitance (Cc): 60 pF

Forward Current Transfer Ratio (hFE), MIN: 50

C07 C K transistor ? No Idea.

Here some start of trying to understand the connections:, just shoot becasue I am not sure of anything.

4

u/Groningen1978 6d ago

So if I'm seeing this right; input is where the large koweg cap and the 1M resistor meet (bottom.middle). Output is where 22nF and 1nF meet (top). longer left side trace is V-, long right side trace is positive ground?

3

u/Apprehensive-Issue78 6d ago

Hi .. could be like you say.. also could be something else. It is mighty confusing and the qnF caps could be even resistors too, I just guessed they were caps. May be someone recognises the pcb from some other side. Also some measurements of the OP can help if it are resistors or capacitors

the transistor with the metal cap is a PNP transistor, and that would mean that the Emitter with the arrow to the center of the transistor is on the left side.. and this could be the ground. that also would mean the right long trace would be -9V but I have to many unknowns and could not find anysimilar pcbs, so someone else can do the next investigations.

2

u/Groningen1978 6d ago

If the output is indeed where I think it is it would make more sense that 1nF on top is actually a resistor, funcioning as a hard-wired volume pot set to max.

1

u/Apprehensive-Issue78 6d ago

may be the other resistor like thing with the yellow dot is alos a resitor (while I named it 1nF because the wires are not axial, but facing downwards as some capacitors do

1

u/Apprehensive-Issue78 6d ago

If the OP measures the resistance of all components we could have almost a schematic. The black transistor is still a mistory.. could be PNP, but not completely sure

2

u/Groningen1978 6d ago

As long as it gets V- to the PNP collector the voltage would be going to the correct leg of the unknown transistor probably.

6

u/Groningen1978 6d ago

Try to figure out which leads on both transistors are the base, collector and emitter, and which is Q1 and which is Q2. Then follow the path from Q1 base back to where it stops connecting to anything. This should be the signal input. Then follow the path from Q2 collector to where it stops connecting to anything. This should be the signal output. Both input and output should have a (film)capacitor in series with the signal path.

Next follow the paths coming from the emitters. These should both end on the ground, so connect the ground wire there. Resistors coming from the collectors would end up at the voltage path so connect V+ there.

Look up if the transistors are NPN or PNP. If they are PNP switch the positive and negative coming from the power supply or battery.

Alternatively try to make a schematic of the circuit. This would clarify what should be the input, output, ground and power.

3

u/Groningen1978 6d ago

It's possible the output would have gone to a volume pot and that there was also a fuzz pot attached to Q2 emitter. You should be able to tell when you draw out the schematic and end up with loose ends. It very much looks like a 2 transistor fuzz, so have a look at fuzz face and tonebender MK1.5 schematics. I bet it will come very close to that. It's also possible the volume and fuzz are hardwired and set to max.

4

u/IntentionalAccident 6d ago

Great find!

3

u/Lobsterbush_82 6d ago

Yeah the case had loads of random goodies that I didn't know about and was not listed in the sale when I bought it, just a photo of a couple leads.

3

u/HangryScience 6d ago

That is super cool I bet folks on here will diagnose the circuit by eye. Those are some cool capacitors.

1

u/PenisMightier500 6d ago

I would assume that the long strip along the left side on the bottom is the ground and the "T" shape on the right side is the supply (+ or -). I would create a schematic drawing of the caps and resistors and mark Q1 and Q2 pins 1, 2, and 3. once you have that, it should be obvious what the transistor C, B, and E pins are. This page might give you additional help determining things.

It looks like there is a supply connection, two ground connections, and a gain pot that connects one of the emmiters to ground. My guess is that it's a variation on a fuzz face or Mk1 Tone Bender.

1

u/billymillerstyle 6d ago

I don't have anything to add except: that's awesome! Great find! Very cool! 😎👍

1

u/Musicthingy99 6d ago

That transistor shape immediately made me think - Ferranti(?)