It was the third green wire. How am I lucky? None of the tubes' filament light up... haha I suppose it could always be worse.The connector type uses insulation displacement (IDC) to connect the wire core to the pin contact. The wire is pushed down between contact tines, which cut into the insulation and grip the copper wire. Not perhaps the most reliable way to handle heater current. The connector might be a Molex, but the Molex site parts finder is horrible. An Amp parts place might have something, as I don't think Mesa were alone in using these those.
The wire colours are hard to read on the schematics I found. They're written shorthand (BRN = Brown). The best I can make out is the heater wires are a pair of green with a ground centre tap in Grey or Green with a yellow stripe. There shouldn't be current in the ground wire, so it might be one of greens that's burnt up.
You might be lucky, and it's only excessive heater current that's made the IDC with the highest resistance heat up, oxidise the wire contact which made it a progressively worse connection that only got hotter until this happened.
That kind of thing could still happen even if the heater current was normal for this design, if a wire IDC was less than perfect.
Statistics: Posted by KinDesu — Sun May 05, 2024 1:24 pm