Mudbunny green russian low volume

[garfo]

Is it working properly now?

[Dave1992]

Not so far :/

[playpunk]

Check your caps....


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[garfo]

First, make sure you have no soldet bridges. Then, one by one, Check all your resistors to see If they are the right value. If necessary use your DMM, then Check the caps. If you have Sound coming out, something might be misplaced. Also chech the transistors. Do some pinout comparissons in case you replaced trainies.

[Dave1992]

Hey guys, just managed to clean the board with some isopropyl alcool & the board started working correctly. Maybe there was a tiny bridge somewhere. Anyway thanks for the help, really appreciated! 

[Muadzin]

I had the same problem with a vero layout Muff, low volume even with the volume maxed out. DMM showed I had normal voltage on all transistors. Using an audio probe I noticed that I had good signal until after Q3, with the problem being in the tone stack. The signal going to lug 1 of the tone pot was good, but the one going to lug 3 was fizzing out. Turn the tone knob fully CCW and you had volume, start turning it CW and the volume went down. I'm still not sure what happened but the signal degraded after the 3n9 cap. Oddly enough if I disconnected the output from that cap (so just input, output end sticking out in the air) to see if the cap was bad the signal was okay. Solder it back into the circuit and fizzing out again. I tried desoldering the grounding resistor and lug 3 and only with them both gone did the signal volume turn good again. Really weird. Still not sure what went wrong. I made a new vero board and populated it with new components and now it works as it should.

[Dave1992]

Ok guys so me again... Took the time to sit down and play with the pedal and there is something else that I didn't notice the first time around: depending on where the tone knob is set there's a weird pulsating sound ( treble side) or a kind of woosh (bass side)

[Dave1992]

So I've checked some other reading on the board:
R6, R12, R17, R20, R22, C14 and C15 all read 9V (or so)

I also did check the voltage reading on C2, C3 are reading 1,18V
C5, C6, C8, C9 also read 1,18V but 0,02V on the diode side.

C1, C4 read 0,03V
C11 is reading 0,37V
& C13 read 0,97V

Should it be reading these voltages or are they wrong???

[Dave1992]

Any one???

[mgwhit]

So I've checked some other reading on the board:
R6, R12, R17, R20, R22, C14 and C15 all read 9V (or so)

I also did check the voltage reading on C2, C3 are reading 1,18V
C5, C6, C8, C9 also read 1,18V but 0,02V on the diode side.

C1, C4 read 0,03V
C11 is reading 0,37V
& C13 read 0,97V

Should it be reading these voltages or are they wrong???

It would be much more helpful for you to post your transistor pin voltages.  I'm guessing your Collector voltages are too low.

[Dave1992]

Yes, the collectors are too low

Q1 read 0.12;0.76;5.14
Q2 read 0.11;0.75;5.77
Q3 read 0.75;1.38;6.20
Q4 read 0.11;0.75;5

They used to be even lower though

[midwayfair]

Yes, the collectors are too low

Q1 read 0.12;0.76;5.14
Q2 read 0.11;0.75;5.77
Q3 read 0.75;1.38;6.20
Q4 read 0.11;0.75;5

They used to be even lower though

Q3 is wrong. Look at the schematic -- it has the same parts and biasing as Q2. So how can its biasing be SO significantly different? How can its emitter voltage be so high if there's only a few hundred ohms there?

[Dave1992]

Yes, the collectors are too low

Q1 read 0.12;0.76;5.14
Q2 read 0.11;0.75;5.77
Q3 read 0.75;1.38;6.20
Q4 read 0.11;0.75;5

They used to be even lower though

Q3 is wrong. Look at the schematic -- it has the same parts and biasing as Q2. So how can its biasing be SO significantly different? How can its emitter voltage be so high if there's only a few hundred ohms there?

That's the part I don't get as well... I've checked both bias resistor & they do in fact read 12k each. The emitter read 390R as it should... Any idea what might be causing this? Is the reading on Q1,2 & 4 any good though?

[midwayfair]

Yes, the collectors are too low

Q1 read 0.12;0.76;5.14
Q2 read 0.11;0.75;5.77
Q3 read 0.75;1.38;6.20
Q4 read 0.11;0.75;5

They used to be even lower though

Q3 is wrong. Look at the schematic -- it has the same parts and biasing as Q2. So how can its biasing be SO significantly different? How can its emitter voltage be so high if there's only a few hundred ohms there?

That's the part I don't get as well... I've checked both bias resistor & they do in fact read 12k each. The emitter read 390R as it should... Any idea what might be causing this? Is the reading on Q1,2 & 4 any good though?

Check all the resistors connected to that transistor. replace them if you have to. When you say "reads" are you using your eyes or a multimeter? Your eyes are very bad at telling you how many ohms something is.

[Dave1992]

Yes, the collectors are too low

Q1 read 0.12;0.76;5.14
Q2 read 0.11;0.75;5.77
Q3 read 0.75;1.38;6.20
Q4 read 0.11;0.75;5

They used to be even lower though

Q3 is wrong. Look at the schematic -- it has the same parts and biasing as Q2. So how can its biasing be SO significantly different? How can its emitter voltage be so high if there's only a few hundred ohms there?

That's the part I don't get as well... I've checked both bias resistor & they do in fact read 12k each. The emitter read 390R as it should... Any idea what might be causing this? Is the reading on Q1,2 & 4 any good though?

Check all the resistors connected to that transistor. replace them if you have to. When you say "reads" are you using your eyes or a multimeter? Your eyes are very bad at telling you how many ohms something is.

I'm using a dmm. So I've checked the resistors on all four Q & they are all good except R3,9 and 14 wich read 38.8K instead of 100K and R21 81K instead of a 100 as well.
I'll go buy new resistors this week and see if that does the trick! Could the probleme be there???