Hi everyone...
This seemingly simple job has become a total time vacuum and I'm not really
sure what's going on.
Symptoms: Low output from the preamp & Treble control doesn't work.
Attempted remedies: Rebuild PSU. New e-caps throughout and subbed in for tantalums in the tone section.
Work-arounds: After FET 3 is an effects loop. If I plug my test signal into the return jack, the circuit is very loud and clear. Also, if I plug my test signal directly into the wiper of the treble control, the pot IS responsive.
I'm usually good at spotting previous repair work but this isn't so clear. However, the original parts list shows all FETs in this circuit (9 total) to be SK30A-Y. However, all but FET 1 are actually p/n 2N3819.
I've been pouring over data sheets but I really don't know what I'm doing. Furthermore, I don't generally use NTE subs but the 2 aforementioned FETs call up different NTE part numbers, which makes me suspicious.
Replacing the original SK30A-Y in position 1 with 2N3819 makes the signal way lower... so maybe the original FETs are required to get this going again? But the treble control doesn't work with either...
Can someone please check me on this? I'm certain I'm missing something when it comes to these transistor part numbers.
Thanks!
This seemingly simple job has become a total time vacuum and I'm not really
sure what's going on.
Symptoms: Low output from the preamp & Treble control doesn't work.
Attempted remedies: Rebuild PSU. New e-caps throughout and subbed in for tantalums in the tone section.
Work-arounds: After FET 3 is an effects loop. If I plug my test signal into the return jack, the circuit is very loud and clear. Also, if I plug my test signal directly into the wiper of the treble control, the pot IS responsive.
I'm usually good at spotting previous repair work but this isn't so clear. However, the original parts list shows all FETs in this circuit (9 total) to be SK30A-Y. However, all but FET 1 are actually p/n 2N3819.
I've been pouring over data sheets but I really don't know what I'm doing. Furthermore, I don't generally use NTE subs but the 2 aforementioned FETs call up different NTE part numbers, which makes me suspicious.
Replacing the original SK30A-Y in position 1 with 2N3819 makes the signal way lower... so maybe the original FETs are required to get this going again? But the treble control doesn't work with either...
Can someone please check me on this? I'm certain I'm missing something when it comes to these transistor part numbers.
Thanks!