Thanks for the U2 clarification Tony_G!
I had mentally skimmed over the A10U2 symbol as being some kind of Op-Amp or something! These schematics are foreign to me “Ahn I will not lie.”
But that makes things much clearer now. It’s also very interesting to me that it’s involved with the attenuator protection “crow-bar” circuit. A lot of things have pointed to this area since the beginning. Recall that I found F1 bridged with a wire when I opened her up initially. I’ve tacked in a 2A fuse at the F1 position for now, and it hasn’t blown yet. But I think you’re right in that the main regulator U2, might need more scrutiny.
I’m hearin’ your hint swainster, thanks for the insight! I’m studying things and thinking about how I implement your suggestion and trying to keep up with you guys. In the meantime I’m occupied by stabilizing the “damage” I’ve done at this point, getting the removed IC pins and pads ready for re-install, improving solder joints, etc.
Speaking of appreciating the community, it’s really interesting to me how things are moving back towards the main regulators and rectifier in the troubleshooting discussion. The reason being, is that “Buddy”, of the YT channel “The Radio Shop”, did a real solid troubleshooting job on the power section of an 8656A a while back. Link is here:
I think I’m going to look forward to removing, cleaning, testing, and re-seating those TO-3’s. Peaceful work!
Always appreciate the thoughts folks! I’ll report back soon.
JRH