The 1987 Lead Mark II schematic had two 10K/1 W power resistors in series after the choke prior to PI and the latter 2204 has only one 10K/1 W after the choke prior to PI. Those are the main changes that caught my eye so far-still looking. I think the other two filter cans are replacements too. Also the 50uF/50uf cap can associated with V1 and V2 power supply filtering has been replaced and they just run the new leads above the board(white wires) and just tagged on to the 10K/1W resistor leads. I see some black burn marks on chassis around the replaced octal socket. I tell you, I'm in the school of Marshall and it's somewhat different from Fenderīut that's OK! A little different perspective.Ģdeaf, you are right! this thing appears to be biased for EL84's already! Only thing with my Mutli-Meter seems like it hard to make contact sometimes with nail polish acting as an insulator. It works pretty good because it easy to see what's changed. Thanks for cluing me in on the nail polish. So I will eventually get to the meat of the issue. I'm still in recovery mode from my vacation playing catch up. First I've got to go to a funeral of an old friend that passed away. I've been trying to do all my internet stuff on my phone and you know how that is in dealing with schematics:>) So now I can actually print out a hard copy of the schematic and study it. So I just got it back yesterday from repair and got it fired up. When I got back from my vacation I found my computer crashed when I tried to boot it up. So it's a little fuzzy right now what to do. I first read about a 47K resistor in the bias and the fix was to parallel another 47K beside it and then a lot of the post on this thread indicated something else. I haven't had time to research what the change over from 6550's to E元4's requires, so I left it alone so far. So I haven't got any 6550's, wish I did because I would love to hear it with those. No I haven't fired it up because the customer sent a new set of JJE元4's in it in anticipation my re-bias.
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