Reply 20 of 25, by Carstenl
Great Job 😀
I have got the excatly the same problem on my model 80-111 !!
It is the same problem as you have described in your first post.
I have been looking at the schematics for the model 80 , and found the Hex inverter ( U185C ) and it is connected to pin 18 on the SRAM.
I do nat have a scope, so I can not do the same probing as you did
My questions is now, could it be an idea to try and ground the output from the Hex inverter ?
I´am not an electronics engineer 😀 , but I can use a soldering iron and a multimeter 😀
Happy New Year -