31 Dec
2021
31 Dec
'21
9:49 p.m.
Hello, do we have any members that can assist with Ti-99/4a motherboard troubleshooting? I've already checked most of the "low-hanging fruit" (voltages, clocks, overheated chips, traces, caps, troubleshooting steps etc.) and i've been looking at pulseview output of various things with one of those inexpensive 8-channel FPGA logic analyzers <https://www.amazon.com/KeeYees-Analyzer-Device-Channel-Arduino/dp/B07K6HXDH1> you can pick up off amazon for $13. This unit has the classic "black screen and tone of death" going on. So far I haven't been able to find anything wrong except the 9900 seems to go into a ROM/RAM R/W loop. Never makes it to the GROMS. Bart