I'm an amateur working on a 10+ yr. old Carvin MTS-3200. The amp came to me sounding weird. Re-tubed it and it sounds good, except that I'm not sure the distortion channel sounds right (never heard one of these before). Distortion is generated by Zener diode clippers. The distortion is very abrupt. There is also a strong low frequency (sounds like a sub-harmonic) tone that is emitted at the early part of a note - when you first pluck the strings. I'm thinking that the distortion problem and the voltage discrepancies might be related.
The schem says I should be seeing 185V on the plates of V2 on both sides of the tube. What I see, however, is 334V on pin 1 and 242V on pin 6. What can be causing this? Also have too-high voltages on V1 and too-low voltages on V4 (see chart below).
The heaters for V1 and V2 are on DC. I'm only seeing -2.3V on pins 4, 5 and 2.3V on 9 (referenced to chassis). Is that correct???
I'm not so much concerned with the other tubes, but V2 voltages look ridiculous to me and that tube is in the distortion channel (where I think- things don't sound right). I've tried subbing in different tubes in V2 and although the voltages changed, they were still high (higher than before, in fact).
HELP!! I don't know what to do next.
Link to schematic: http://www.carvinservice.com/crg/sch...00%20REV-E.pdf
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The schem says I should be seeing 185V on the plates of V2 on both sides of the tube. What I see, however, is 334V on pin 1 and 242V on pin 6. What can be causing this? Also have too-high voltages on V1 and too-low voltages on V4 (see chart below).
The heaters for V1 and V2 are on DC. I'm only seeing -2.3V on pins 4, 5 and 2.3V on 9 (referenced to chassis). Is that correct???
I'm not so much concerned with the other tubes, but V2 voltages look ridiculous to me and that tube is in the distortion channel (where I think- things don't sound right). I've tried subbing in different tubes in V2 and although the voltages changed, they were still high (higher than before, in fact).
HELP!! I don't know what to do next.
Link to schematic: http://www.carvinservice.com/crg/sch...00%20REV-E.pdf
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