IIGS not resetting

Yes, the 200K is part of the power-on reset circuit for the ADB MCU. That plus the reset switch on the keyboard should cause it to pull the RESET.L line low for a short time to reset the motherboard. If you are sure that pin 49 is not connected (and that the trace it connects to is not shorted to another trace nearby), then you are correct in looking for  what is pulling the line high. Everything else it connects to should either be an input or an open-collector output. So if pulling the line high through a 10K resistor does not work, then you need to find what other connection is pulling it high. Looking forward to seeing what you find.

pcbishaf wrote: Jeff d - I will have to get back in more detail when I get back on the project. However, you mentioned that there are "some Apple folks" meeting in Springfield next week. I won't be able to make that gathering but I would really like to get into the loop that even knows that a gathering of "Apple folk" is happening. If you could help me get in touch with the organizer, maybe I can make the next gathering.

It's here: Kansasfest I believe the response to this new venue was very favorable and they will likely be back there for 2025.