Hi, This is my 4th build (first 3 successful and sound great). However, with this one, all I'm getting is a loud hum and low-level distorted signal when on. Bypassed signal is fine. I've double checked my soldering, capacitor polarity etc. and everything looks fine. Can anyone see any problems in the attached photo? Perhaps it's my wiring? Any help is greatly appreciated. Thanks.
You might want to measure the voltages to gnd at all pins of the ic and post them.
Good luck Christof
Thanks Christof. I checked the voltage of all the pins:
Pin 1 = 4.05
Pin 2 = 4.05
Pin 3 = 0.87
Pin 4 = 0.00 (I assume this is grounded?)
Pin 5 = 7.57
Pin 6 = 3.75
Pin 7 = 3.90
Pin 8 = 7.57
I also tested the positive wire of the power socket. It measures zero voltage when switched off and 7.75 when switched on. My other pedals measure full 9v when off and on so I assume there is something wrong here.
Again, thanks for you help.
These Voltages are surprising.
What are the voltagees at c9 and c100?
(The circuit is somewhat strange. R13 r14 c7 are useless in my view. R5 is ? )
Perhaps there is some short between two soldering points. Have A very close look.
C9 = 4.35, C100 = 8.80
It was a bit tricky to get a reading from C9. Numbers were jumping around a bit. I had a pretty close look at everything and can't see any bridging. My soldering is actually pretty clean on this one.
My hypothesis is, that there is something wrong with c9. The voltage seems not to be stable here.
I would first resolder it. If this does not help I would use a fresh 47uF here,10 times bigger.
And I would take R5 out.
Good luck. Christof
Ok, I'll give that a try when I get a chance. Thanks a lot for you help Christof.
As suggested by Christof i resoldered C9. Unfortunately no change. I didn't have a fresh 47uF to replace so wasn't able to check that. Then I noticed that the pins for the Bass and Treble pots are sitting very close to the casing of the Mid and Level posts. I'm not sure if it's a problem if they're touching, but I went ahead and stuck some adhesive insulation pads between. This seems to have fixed the distorted signal, and the buzzing has reduced considerably (but still there). However, now I can hear that the bass, treble and mid pots do absolutely nothing and the volume pot get louder until about 2/3rds of the way round and then drops off again. Any advice much appreciated. Cheers. Pete.