Big Problem Pi

[DUCKFACE]

what is wrong with this one ?
no sound - no nothing ..
anyone see any problem ?

[DUCKFACE]

somebody ?
someone ?

[Quackzed]

schem  looks ok to me, just a quick look but its a big muff /maybee with a few tweaks ?. check wiring, measure voltages on transistors....

[DUCKFACE]

wiring is ok
transistors are ok too
voltage +8.86v

[blackcorvo]

Measure the voltage in all transistors's pins, and post them in here. That will make it a lot easier to point out what might be wrong.

[anchovie]

what is wrong with this one ?
no sound - no nothing ..
anyone see any problem ?

The problem is that all you've posted is a giant schematic that's several times the size of my screen.

It tells us nothing about how you actually built the thing. Please read and follow the "DEBUGGING" sticky thread.

[DUCKFACE]

is it better ?

[the3secondrule]

http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

^^^click me 

[slacker]

If LD1 hasn't already exploded, remove it. The circuit won't work with it in there. the LED will pull what is supposed to be 9 volts down to a couple of volts. After that do what the other guys have said, without more information it's impossible to say what the problem is, it could be anything.

[DUCKFACE]

for LD1 you are right - there suppos eto be a resistor 1k but led is not in place yet (not soldered)
T1
e: 4.48
b: 0.75
c: 0.14

T2
e: 4.97
b: 0.73
c: 0.12


T3
e: 4.88
b: 0.73
c: 0.12


T4
e: 5.24
b: 1.30
c: 0.78

D1 and D3 C: 0.73 A: 0.46
D2 and D4 C: 0.46 C: 0.73
voltage 8.89V regulated
one of the mods are capacitors input 100pf to ground and 100pf ti the end stage power supply
1mf for input signal and 1 mf on second diode stage (wima 1mf mks4)
another one is tone blend

[R.G.]

I believe you are misidentifying the collectors and emitters. The emitters on the schemo have an arrow on them. However, the voltages look OK if it was a simple mislabel of the C and E.

That makes it most likely a wiring or solder problem in the audio path. It's time for you to learn about audio probes. Make and use an audio probe to follow the audio signal into and through the circuit.

[Mike Burgundy]

Voltages don't look too wrong to me. Transistors are biasing. Try and trace the signal (audio probe, search the forum) and see where you suddenly don't get signal any more. There's your problem.
Put a test signal (1KHz 100mV sine, strummed guitar, recording, whatever) on the input, check the input jack for signal. Should be there. Next, check signal at both sides of the input cap. Still there? Okay, wiring and input cap good. Check for signal on the B *leg* of T1. No signal? Soldering of T1. Signal there? - move on. Check for signal on C leg of T1. Solderpad C T1. Coupling cap both sides, gain pot etc. This should find the problem area quite accurately, then figure out what it is exactly. My guess would be soldering, and I'm kinda drawn to the gain pot and tone stack, but you never know.
RG-beat me to it. And I totally overlooked the E<>C switch....

[R.G.]

RG-beat me to it.

Nah. Great minds drink coffee at the same time. 

[DUCKFACE]

okey ... i got to base of T4 ... and after that - nothing - mute

[Mike Burgundy]

Well done. While we wait for RG to get coffee (I tip my hat to you, sir) experiment a bit more.
Signal on T4 base, but nothing on collector or emitter? Did you check both on the legs of the transistor and the pads? The transistor biases, suggesting its fine (you may want to recheck to be sure). I think you may find signal on the emitter - this would suggest a short to ground or bad connection just behind the collector. Dink around a bit and see if you can get anything to change - for example lift c3 and see if you have signal out of T4 now.

[Gus]

As Mike posted check the output cap and volume control, is C3 connected is the volume control OK?.  T4 DC voltages look OK.

[DUCKFACE]

thanks a lot
voltage of T4 was crazy ...
i fix it ...
but i have a question ... how to make sound not so ... metalic ...
i want it warm soft juicy

[Quackzed]

 

[Mike Burgundy]

Glad it's working. Could you satisfy our curiosity and explain what was wrong? The voltages for T4 you reported earlier looked ok.
And now, welcome to the true heartland of DIY - modding.
Be advised a Muff is designed to be a balls-to-the-wall smashing pumpkins type wall of sound. If it's too harsh (=metallic?) you can tame the highs. If its too distorted (=metallic?) you can lower gain, increase clipping thresholds, change diodes, transistors, change gain/biasing schems, change inter-stage filtering, etc.
Search this forum and google on Big Muff mods and see what you can find out. There's so much tinkering you can do...

[DUCKFACE]

C2 was a problem ...
when i remove it .. everything was ok.
I put another capacitor - 470pF - sowund was kind of bassy.
change it with 100pF - again noting. so 470pf stays for now. im using this big pi for bass. but on low freq is realy creapy .. thats why i want to make it sound more warm. i think that gain is ok ... but the peaks of sound are not so close to eachother.... maybe another clipping diods gonna do a nice work.