Howdy. I am troubleshooting the Cobbler Preamp ( Victory v1 Copper clone) and I think the voltages are way off. the input voltage is 9.44 and drops to 9.41 after the d100 diode... ok so far (I think) Followed by R100 a current limiting resistor in series. There is no continuity between the negative d100 diode and the r100 resistor...... I physically bridge the resistor leg to the the Diode and now only get 3.4 volts to pin 1 of the ic100 charge pum (tc1044scpa) . Something must be wrong? The voltage should be something near 8.5 volts? Any help would be great full! See schematic here:
https://docs.pedalpcb.com/project/Cobbler-PedalPCB.pdf
Pics..??
(https://i.postimg.cc/2VFtPJ20/IMG-0735.jpg) (https://postimg.cc/2VFtPJ20)
(https://i.postimg.cc/K1GWFNWx/IMG-0737.jpg) (https://postimg.cc/K1GWFNWx)
Thanks!
your IC2 appears to be upsidedown in its socket.
I think you killed IC2 (reverse polarity power supply) resulting into significant current draw (about 60mA, judging from voltage drop across 100R resistor)..
Take IC2 out of socket and take new measurements.. :icon_wink:
Quote from: antonis on November 29, 2023, 05:49:44 AMTake IC2 out of socket .....
..... take it to the back door, and throw it as far as you can. then get another TL.
Hello. I wish it was that easy!!! I was swapping them out and I put them in backwards... but thanks for noticing!! I did get some sound but it was static, similar to a fuzz pedal that is not biased correctly but only worse... I hit a chords and static comes out a second later. I did take some voltages as follows:
Ic100
1 - 5.60
2 - 4.89
3 -1.56
4 - .154
5 - .769
6 - 5.18
7 - 4.56
8 - 4.62
Ic1
1 -2.97
2 -2.56
3 - 1.60
4 - .762
5 - 1.04
6 - 4.13
7 - 3.48
8 - 4.53
Ic2
1 -2.83
2 - 2.27
3 -1.54
4 - .760
5 - .804
6 -3.85
7 - 4.2
8 - 4.53
Does this make sense at all? Thanks!!
Quote from: yalesmith on November 30, 2023, 06:59:35 PMDoes this make sense at all?
Unfortunately, No.. :icon_wink:
Take both op-amps (IC1 & IC2) out of sockets and take measurements on IC100..
(Black probe permanently on GND and Red probe on respective pins - beware of measurements negative signs..)