My Mark III is fried...

  • Thread starter Thread starter anomaly
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anomaly

anomaly

Well-known member
:(

Turned it on and it sounded glorious for about 15 mins at a fairly moderate volume and then all of a sudden a huge volume drop and now the amp sounds like a damn clock radio (i didn't smell anything burning)...changed the power tubes, nothing...cleaned the effects loop jacks, nothing.

All channels are the same...really quiet. The sound is still there though.

A pre-amp tube maybe?? All of the tubes are lighting up.
 
Thats what I would check next. You can plug your guitar into the effects return to see if the power amp is working. :confused:
 
stephen sawall":2b7stidi said:
Thats what I would check next. You can plug your guitar into the effects return to see if the power amp is working. :confused:
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+1
 
OK, i tried that and the poweramp is working. So something in the pre-amp... hopefully just a pre-amp tube.
 
Is it the same in all three modes V1 or phase would be my guess ?
 
Changed all of the pre-amp tubes. No luck. :confused:

Not good, not good at all. :(
 
Did you do the tubes one at a time ? I have seen people do that and get an other bad. There is only one fuse if I remeber. I take it that you are going guitar -amp nothing in loop. You may want to clean the master / etc.
 
both channels all clicking all the known pre-amp options on and off? Reverb if it has it, as well...
 
anomaly":wr1fdshf said:
An LDR maybe?
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that would be my guess, maybe there are some some voltage measurements posted somewhere so you can check them.
 
sounds like your output transformer isn't happy.... Do you have a good tech by you? or access to a scope?
 
dawnofdreamx97":2r2n0fu0 said:
sounds like your output transformer isn't happy.... Do you have a good tech by you? or access to a scope?
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If plugs into the power amp side (effect return) the amp makes noise so we know that the OT is working?
 
No burnt resistors or caps or anything inside...

Anything else i should check??
 
how much do you think it would cost to send it to Mesa to get it fixed there?

BTW i'm in canada
 
Do more than clean the fx loop jack, plug a cord in there from send to return. Still act the same?

Pete
 
anomaly":1495npsr said:
yeah, i tried that.
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Sorry, didn't read that. Maybe a dirty master volume pot? Sounds like it's time to take it to a tech.
 
stratotone":3s2wama6 said:
anomaly":3s2wama6 said:
yeah, i tried that.
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Maybe a dirty master volume pot?
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hmm... didn't think of that. I'm going to take some contact cleaner to all the pots tommorow and see if that does anything.
 
Master and input jack are the ones I have seen go bad the most on amps.
 
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