I have a 1980 100w JMP here. Looking for a close schematic..Ive got a few but nothing dead on. Its a 2203--JMP Mk2 Master Volume --unclear on inputs--looks like 4 factory holes. Unclear on speaker jacks--looks like 4 factory holes . It absolutely has can cap holes for SIX caps. Im asking because this thing has been cut / modded/ butchered. Im going to return it to stock 1980 wiring..but , im going with 3 , 50/50 filters , and id like to stay with hi/lo ins and 2 speaker outs. EL34's What can you share as far as a 1978-1980 100watt 2203 schematic , EL34 , NON jcm800 ? . Theres a lot of variations on these !!!
That setup showed in the 1980's. Look at the dates for the schematics in the JCM800 section. https://drtube.com/library/schematics/69-marshall-schemas#JCM800
yea...but this is stamped JMP...not jcm800...lots of weirdness from Marshall. Some of those scems..very hard to read values...I know they used leftover parts / chassis at some points during the transition from early 70s 2203 to jcm800 80's 2203
can you post pictures can you post pictures of the insides? It doesn't match the description of a normal Marshall head.
i will tomorrow---this things a mess....but the speaker jack holes look factory ( 4)...and the in jack holes look factory (4) . I cant find a 1980 JMP 2203 MV image like that online.... also , its got the rocker switches and grommet / thru-style ac cord--not a factory IEC style socket.
If it has 4 holes, it would be a 1959 head. If it has 2 holes it would be a 2203 /2204 head. But what you are saying is: 4 hole 2203 head with master volume? From the factory? That's what is sort of odd about it. However there have been "transition amps," which are like a new and old amp blended together. We have seen a few odd ball amps like that from the factory. So it is still possible.
I pointed him to what he is looking to accomplish but yes it seems he has a modded/butchered JMP MKII 1959, yes?, maybe?
