Is this the best thread to share node board troubleshooting experiences?
I recently tried to play my IMDN Pro, and found that Node 9 was not found.
The 6V LED was not lit, so I took the board out of the game and measured a short from the 6V rail to GND.
Since this could be any component that sits between the 6V and GND rails, I started removing components one at a time, trying to hit the most likely ones first.
The D9 diode was shorted after I removed it, but there was still low impedance on the board. It did have the zip tie installed per SB189, and the legs were still intact.
I removed a few capacitors, but mostly because they were easy. I thought maybe C28, the electrolytic, could have failed (it hadn't), but also removed a couple of ceramic caps before resolving to remove U9. Since it has a thermal ground pad, it's more work to remove.
After removing U9, the short on the board was gone, so both D9 and U9 were confirmed dead. Neither showed physical evidence of damage like I've seen in other pictures here.
I connected a bench supply to inject 6V, and the board sprang to life with the 6V lit and status LED blinking.
Replacement parts for all the stuff I removed are on order.