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Mesa Boogie Mark 3, Blue Stripe, 1989

Fell over in the van and broke 3 front pot shafts, of course each compound with push/pull switches, like the other 4 front controls. "repaired" by someone with a little knowlege is a dangerous thing. He even managed to break the replacement ones, breaking the paxolin/rivet joins on switch and pot paxolins. Although correct company numbering , they are a different flavour , in that the relative positions of switch and pot are swapped over. Plus 2 cold solderings, that fell off on first touches. Plus a piece of mains 15 amp wire bridged across a 10K resistor, with copper strands fanned out all around. In the process he's got wires in a complete jumble. So having to start from scratch, this schematic on botofuckit is the clearest I found , despite wrong file name it would seem.

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and p3 Is "lead drive" legend on the amp the same as "drive" on the schematic.? A 2 terminal useage of one pot is 100K on the schematic but 250K in the amp here, maybe replaced in antiquity as 1990 datecode and different batch, but amp was working fine before mishap, so I'll leave at 250K. The two "bright" designations seem to be clear enough, which is which.

Reply to
N_Cook
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For 1989 ser number in 257** range only take the resistors marked with K as to be representative, the Cs seem to be correct. None I've tracked down so far , the R band colours do not agree with that schematic, why 4 band resistors on a valve amp?

Reply to
N_Cook

Call Westside Distribution, Glasgow. 0141 248 4812 They will identify and sell you the proper pots you require.

The customer pays for parts, don't forget.

The customer doesn't particlarly want to pay for additional labour involving not wanting to buy the proper parts from the manufacturer, however.

Gareth.

Reply to
sound.service

All working again as far as all of the pots are concerned and 3 of the pull controls change the sound. No magic smoke or anything overheating. The pull options of Treble- Pull shift Master- Pull deep Lead Drive - Pull Lead Lead Master - Pull Bright no change of sound. It'll be awkward if the "repairer" blew some of the LDRs, but at least they can be checked for function with a low ps only.

Reply to
N_Cook

In hindsight it should have been obvious why no lead mode. There is an error on the Mesa schematic of Mesa Boogie 3 on Elektrotanya. The lead-switch should take the common LDR1 - 4 line, to ground and not directly shorting those 4 leds as in the diagram, doh!

Reply to
N_Cook

Passed a gig and recording session and no bounce back. Its quite easy to recondition the original pot+switches , with new stud ended stem. Much stronger and of course matching action to the others, unlike the flimsey new pots and of course proper pot/sw positions. The new pots , nothing stopping any of the tags turning on their rivets, and they had, at least they've dropped the mains rating of the originals as these rotating terminals would be utterly unsafe for mains use.

Reply to
N_Cook

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