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Big trouble with modded Peavey C30
Hello fellow Ampagers.
I have just done a few of Steve Ahola's mods on a Peavey Classic 30 amp.
This amp is a real PITA to work on for someone with non-pro skills like me, because the soldering eyelets on the PCB tend to ruin at the least touch of iron... Also, it's impossible to test the amp without mounting the PCB back in place totally. This is why I did my mods without individual testing, and now I don't know which mod caused my trouble...
The symptom:
the Normal channel does not play anymore, while the Drive channel is affected not only by the Pre and Post pots but ALSO by the Normal volume pot (which is not... normal, actually!).
It's like the Normal pot was disconnected by the Normal channel and connected to the Drive channel.
These are the parts replaced with a different value (as suggested by Steve in his http://www.blueguitar.org:
C18 bass cap;
C19 midrange cap;
C14 treble cap;
C11 boost cap;
R12 boost resistor to ground;
C4 cap from V1 to V2;
C7 cap from V1 to V2 (eliminated);
C1 and R5 between V2A and V2B;
R9 grid load resistor to V2A;
C2 coupling cap between V2A and V2B.
Plus, I have installed a bias adjust trim pot.
I have already taken out the PCB and checked all the replaced parts, but did not find any clear issue. Actually most solder joints are not that good (due to partial breakage of the eyelets), but all of them are solid and continuity is where it's supposed to be.
Will you please direct my troubleshooting towards the potential culprit among the mods I did?
Schematic and layout drawings are attached.
TIA,
Carlo
I have just done a few of Steve Ahola's mods on a Peavey Classic 30 amp.
This amp is a real PITA to work on for someone with non-pro skills like me, because the soldering eyelets on the PCB tend to ruin at the least touch of iron... Also, it's impossible to test the amp without mounting the PCB back in place totally. This is why I did my mods without individual testing, and now I don't know which mod caused my trouble...
The symptom:
the Normal channel does not play anymore, while the Drive channel is affected not only by the Pre and Post pots but ALSO by the Normal volume pot (which is not... normal, actually!).
It's like the Normal pot was disconnected by the Normal channel and connected to the Drive channel.
These are the parts replaced with a different value (as suggested by Steve in his http://www.blueguitar.org:
C18 bass cap;
C19 midrange cap;
C14 treble cap;
C11 boost cap;
R12 boost resistor to ground;
C4 cap from V1 to V2;
C7 cap from V1 to V2 (eliminated);
C1 and R5 between V2A and V2B;
R9 grid load resistor to V2A;
C2 coupling cap between V2A and V2B.
Plus, I have installed a bias adjust trim pot.
I have already taken out the PCB and checked all the replaced parts, but did not find any clear issue. Actually most solder joints are not that good (due to partial breakage of the eyelets), but all of them are solid and continuity is where it's supposed to be.
Will you please direct my troubleshooting towards the potential culprit among the mods I did?
Schematic and layout drawings are attached.
TIA,
Carlo
Attached Files
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