TucsonSean
New member
- Joined
- Nov 10, 2009
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Hello Everyone,
I have a Mk IIC+ (Serial #12603) and am in need of some guidance. About 1 mo. ago, I noticed that the clean channel started having some distortion in the background. It sounded like having a second distorted amp at a much lower volume but coming through the same speaker. I tried lowering Vol 1 to below 5 and I could still hear it. I even tried lowering my guitar's volume control (I have EMGs) and it didn't help.
I have yet to pull the chassis from the enclosure but I am suspecting that maybe the channel switching LDRs (LDR 2 and 4 from the schematics) are on their last legs or the supply to them is acting funny. Are there any other possibilities? The output tubes are less than 2 years old with less than 1 year of moderate playing on them. The preamp tubes are all SPAX7 from Mesa, bought new back in 96 but I know that I don't have more than 3 years total playing time on them. I have been considering sending it up to Petaluma and have MB work it over but as cash is a little short right now and I have the skills to fix it (BSEE) I figure that I could look it over first.Any help would be appreciated.
A little background info: The amp is a 60W, short head with reverb that I picked up back in '94. The blues player that I bought it from back in Indiana said that he didn't think is sounded any good, that the bass was too flabby and he couldn't afford new tubes. I looked it over and played it for a couple of minutes before saying "Yeah, it doesn't sound too good, maybe new tubes would help. Then I noticed that the bass control was set to 8 and pulled out and offered to take it off of his hands for $350. He smiled and said " $350 would be great. Good luck, maybe you can figure out how to get a better tone out of it." I smiled all the way home listening to And Justice for All thinking I was the luckiest man alive at the time. Man, those are some good memories!
-Sean
I have a Mk IIC+ (Serial #12603) and am in need of some guidance. About 1 mo. ago, I noticed that the clean channel started having some distortion in the background. It sounded like having a second distorted amp at a much lower volume but coming through the same speaker. I tried lowering Vol 1 to below 5 and I could still hear it. I even tried lowering my guitar's volume control (I have EMGs) and it didn't help.
I have yet to pull the chassis from the enclosure but I am suspecting that maybe the channel switching LDRs (LDR 2 and 4 from the schematics) are on their last legs or the supply to them is acting funny. Are there any other possibilities? The output tubes are less than 2 years old with less than 1 year of moderate playing on them. The preamp tubes are all SPAX7 from Mesa, bought new back in 96 but I know that I don't have more than 3 years total playing time on them. I have been considering sending it up to Petaluma and have MB work it over but as cash is a little short right now and I have the skills to fix it (BSEE) I figure that I could look it over first.Any help would be appreciated.
A little background info: The amp is a 60W, short head with reverb that I picked up back in '94. The blues player that I bought it from back in Indiana said that he didn't think is sounded any good, that the bass was too flabby and he couldn't afford new tubes. I looked it over and played it for a couple of minutes before saying "Yeah, it doesn't sound too good, maybe new tubes would help. Then I noticed that the bass control was set to 8 and pulled out and offered to take it off of his hands for $350. He smiled and said " $350 would be great. Good luck, maybe you can figure out how to get a better tone out of it." I smiled all the way home listening to And Justice for All thinking I was the luckiest man alive at the time. Man, those are some good memories!
-Sean
