Was/is there a Mark IIA upgrade path to IIB?

[scelerat]

...and how can I tell if that was done to my Mark IIA?

I bought a Mark IIA about a year ago from the original owner. It included a bunch of original paperwork, brochures, price lists, magazine reviews, etc. Interestingly, it included manuals for *both* the Mark IIA and the Mark IIB. The seller was sure it was a Mark IIA, it definitely has the Mark II back panel, ie. just the single preamp out/power amp in jack and slave out, no effects loop like the IIB. Yet, at some point a few years after the original purchase the owner took it back to Mesa and had *some* work done on it. The Fetron switch was removed, for one.

Is that all that happened -- removal of the Fetron? How else would I be able to tell, short of visually comparing the circuit to a IIA schematic (something I probably would not do well)? The presence of the IIB manual makes me think something more was done to it -- like they upgraded it to a IIB and threw in the manual for good measure -- but maybe it's just a red herring. Did Mesa regularly do upgrades from IIAs to IIBs or would that have been more of a special order?

FWIW I don't want to change anything about it. The black tolex is practically mint, it's a 60/100 model with GEQ reverb and 12" EVM. Sounds like a million bucks.

 

[domglop78]

Hello
being the proud owner of a Mark2 B I think it is important to have a correct plan depending on the version. In this forum, it is very difficult to have the different diagrams for each version. and yet it is very important to be able to maintain the amp and be able to play. I'm sure someone has already looked at the PCBs for each version ...
many exist for the Mk2 C and C + but not for the previous versions .... the plans of mark 2 and mark2 b are identical everywhere just need a pcb and layout for each version .
it is enough to put once and for all the good plans according to the versions (mk1,2,3,4,5) with the circuits and components.
for all mesa boogie people around the world it is very important to find all informations about our amps.
dom