Hi guys,...........I want to do the Gravenmade mod on my 900 reissue but cant's find the schematics ,.don't know if there were any changes done to the reissue,......emailed Marshall to ask them so still waiting for their answer , anyone here has any clue ? Thanks ! http://www.sgravenmade.nl/onderhoud/marshall-jcm900-dual-reverb-mod/
Try here: https://www.thetubestore.com/marshall-schematics Looks like there is a link for your amp about 1/2 way down the page.
Thanks,.......why is it written JMP52 on the preamp sheet ?........and is 02 the year of revision ? https://www.thetubestore.com/lib/th...rshall-JCM900-Dualrev-100W-4100-Schematic.pdf
I'm not an expert (so don't shoot me if I'm wrong) but I believe the JMP52 is just the drawing number. I would just use the 'DATE' field for drawing/revision date. I think the 02 is the revision number. The 'MODEL' field is for your amp (4100) and looks like the same preamp is used in both the 4100 and 4500 models.
Question? Do the original JCM900 4100 Dual Reverb (two different versions: EL34 and 5881) and the JCM900 4100 Reissue (5881) share the same schematic? I ask because there is an original JMP Lead 50W 1987 schematic and a Plexi Superlead Reissue 50W 1987 [1987X] schematic on the page.
I'm not an expert and the schematics on that site may be all that's available to most of us. The folks over at Marshall may have made some changes iteratively over the years that any particular model was available and it's nearly impossible to be aware of all of them. An amp tech would have a much better grasp. All I can suggest is use the schematic that matches your particular model + year + power tube.
