Help figuring out if this Mark III was modded by Mike?

[frontline205]

Hi don’t know if you guys can help with this but I got a Mesa Mark III amp. And I’m trying to figure out if it was modded by Mesa or someone else and what mod is it. I see the R2 mod sticker and a + with MB but maybe the plus was added later? I called Mesa and they said it’s not in their recent records. The person I bought it from said it was sent to Mesa but doesn’t know what was done to it as it was by the previous owner.
Here are some pics if anyone knows anything. Is there a place inside the chassis I should look?

 

[fretout]

The “+” is a normal marking found on several Mark IIIs from the “Black Stripe era”. It appears to be an original marking. Take note that it does NOT MEAN the amp is a III+. The III+ marking is different.

The R2 mod appears to be executed correctly. Mike B always completed my R2 mods with gray wire, but yours appears to be white. I’m not sure if Mike B ALWAYS used gray wire, but it’s certainly worth noting.

Also Black Stripes were made before the Reverb Mod was performed by Mesa/Boogie. When you send in an older Mark III that shipped before the Mod was done, Mike B ALWAYS wants to update these older Mark IIIs with the Reverb Mod, even if the owner requests that he not. When Mike updates the amp and performs the Reverb Mod, Mike will write an “R” next to the power outlet in Red marker. This can be an indication that Mike B serviced the amp at some point.

FWIW, the R2 Mod is pretty easy to complete. You just have to be super careful how much heat you apply to the traces. I used to have Mike B complete the R2 Mod anytime I sent in a Mark III for service, but he literally asked me to just do it myself…lol.

I do NOT recognize the other writing next to Mike’s initials. I also don’t think Mike would need to indicate the preamp tube series, or the PI. This would seem to indicate maybe someone else has been poking around inside the amp.

 

[frontline205]

I actually emailed Mesa and they confirmed Mike did the R2 mod and reverb mod. And basic maintenance in 2014. I actually it since to find the IIc+ reissue