SOLVED Integral Preamp Debug

jrbell1990

New member
Greetings all,

I am having trouble finding the source of my issue on this Integral Preamp and was hoping for some insight (maybe from someone who's built this as well??).

Solder-Side

Audio is at about half and sounds like a zipper powered by battery and 9V supply. Q1 seems to be playing a part in this as signal drops entirely when probed on Base and Collector.

Other notes:
  • Subbed 1n4148 for the 1s1588 diodes per recommendation.
  • Used the recommended 35V capacitor values.
  • I have used (and substituted) known-good TL072CP and TC1044SCEPA chips.
  • Q1 and Q2 are BC548C per recommendation and measure appropriately prior to soldering on to the board.
  • R4-6M8 resistor is 4M7 and 2M2 wired in series.
  • I have reflowed all connections at the jacks, grounds, and switch.
I suspect Q1 may just be bad, but I am interested in whatever other possibilities may lead!

I appreciate any and all help!
 
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fig

Village Idiot
Sorry for the delay...what voltage are you running to this pedal?
I think you should have around 17VDC for Vref.
 
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