Well, things are a bit better than I thought because the 3005 schematic matches poorly to the 5005. Post 26 here has a redlined schematic marking the changes: https://music-electronics-forum.com/forum/amplification/guitar-amps/maintenance-troubleshooting-repair/50328-marshall-lead-12-5005-combo-needs-help/page2
The 5005 seems a lot closer to the layout and schematic designations of the 5002 20 watt combo: https://www.drtube.nl/schematics/marshall/5x02.gif Some definite tweaks in the preamp circuit, so maybe the idea that 3005=5005 needs an asterisk next to it.
So my IC1 voltages are from C15 (=17.51) and C16 (=-13.76) in the amp and the redlined schematic. So it's off balance, too high positive and too low negative. And unless that conked out the chip, that doesn't seem to explain the silence. When I have time in a couple months I'll have to get a scope and just trace it out.
The 5005 seems a lot closer to the layout and schematic designations of the 5002 20 watt combo: https://www.drtube.nl/schematics/marshall/5x02.gif Some definite tweaks in the preamp circuit, so maybe the idea that 3005=5005 needs an asterisk next to it.
So my IC1 voltages are from C15 (=17.51) and C16 (=-13.76) in the amp and the redlined schematic. So it's off balance, too high positive and too low negative. And unless that conked out the chip, that doesn't seem to explain the silence. When I have time in a couple months I'll have to get a scope and just trace it out.