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Post by LT on Jul 11, 2017 13:33:10 GMT -7
I know this is the Z forum, but there's a bunch of you guys here that have in-depth knowledge of other amps as well.
I have a 1978 MK1 Mesa Boogie that just came back from Petaluma where I had Mike Bedinelli give it a tune up. I have maybe an hour play time on it since it came back.
I was testing some pedals through it last night and all was fine. I turned the amp off and then back on maybe 15 minutes later, and the fuse blew. I replaced it, turned it back on and all was fine again. I let it run for 15 minutes or so and it ran fine. I took a look at the output tubes several times and didn't see anything of issue. This amp has solid state rectification, so there's no rectifier tube to suspect.
I'll add that I run NOS GE 6L6's which did NOT go with the amp on it's tune-up trip. Do you think I have the start of a failing 6L6? They are both pretty old but appear to be in great shape. Preamp tubes don't take out fuses, do they?
I have a call in to Mesa but wanted to ask you guys your opinion. Thanks in advance!
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Post by benttop (Steve) on Jul 11, 2017 20:02:09 GMT -7
Did you rebias for those NOS tubes?
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Post by zpilot on Jul 12, 2017 0:28:20 GMT -7
You definitely should have sent those tubes in with the amp so Mesa could have biased it to their specs. Of course that's assuming they will tune up an amp with anything other than their branded tubes.
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Post by freddieg on Jul 12, 2017 4:57:28 GMT -7
Mesa tests their branded tubes and they resell the ones that don't meet their specs. I am not an expert but I think it is a safer bet to use Mesa tubes in a Mesa amp.
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Post by LT on Jul 12, 2017 8:09:04 GMT -7
Good points on the tubes. Old Mesa's like this have a fixed bias and I think you guys are right.....Mesa tubes in Mesa amps. I did speak with one of their tech guys and he had me go through the same type of troubleshooting as the Doc does on Z's. I have replaced the GE tubes with an older set of Mesa tubes that I kept as spares. So far, no issues. Thanks for the input!
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