41CX halfnut keyboard not responding

[jebem]

(12-06-2015 08:15 PM)quantalume Wrote:  I have the top half of a 41CX halfnut that I bought from a fellow forum member some years ago. At the time, I only needed the enhancement assembly as a donor for another halfnut. I decided to hook up the remaining main PCB to see if it would work. Applying 6 volts between the negative capacitor lead and common diode anode connection, I get MEMORY LOST but then no response from any of the keys including the power switch. Any ideas on how to proceed with troubleshooting? Thanks.

Assuming that it should work without the rom/enhanced piggy board at the bottom, I would check the usual stuff in these cases:

- Do a visual inspection for pcb broken traces or shorted ones caused by solder;
- Because the rom/enhanced piggy board was removed, check for good continuity between the copper traces on both pcb sides;
- Are all the keys working well mechanically? Even so, I would destroy all those plastic heat stakes/rivets to inspect the other side of the pcb and make sure no key is stuck;
- A final good cleaning warm distilled water followed by isopropyl alcohol to remove any remaining contaminants can help sometimes.