Re: [M100] diagnose

You mentioned the CE line. This sounds similar to the problem that I had with my 102 ram address decoder circuit. I had to replace the demultiplexer. If your lowest ram is not responding properly this might happen? On Dec 14, 2017 8:18 PM, "Fugu ME100" wrote: > If your

Re: [M100] diagnose

If your voltages appear stable and in spec I would leave the caps, unless you see any that have leaked. A white or greenish residue under the cap is usually a good sign it has leaked. I think the green tint is because it also etched the copper under the cap. From: M100

Re: [M100] diagnose

Really appreciate your effort!!! I'll try to measure the suggested signals and get out my bag of GOOD caps :) Mauro Inviato da iPhone > Il giorno Dec 15, 2017, alle ore 01:55, Fugu ME100 ha > scritto: > > It would be interesting to see if the Address Lines fail at a

Re: [M100] diagnose

It would be interesting to see if the Address Lines fail at a specific address all the time. Might give a clue as to what is causing the issue. In the old days it was possible to watch the address lines walk through a count sequence if you had a bad ROM or RAM. Although this one appears to

Re: [M100] diagnose

Unfortunately the NiCd battery was dead and already replaced twice. The unit was without power (no cable or battery) for several days since I struggled to find the NiCd battery. Considering the age of the unit I think most of the electrolytic capacitors are dead. No one suggested to replace

Re: [M100] diagnose

Actually the reset is moving only at power on and when I press the reset button, otherwise it is stable. I tried to follow the reset signal after the Reset out of the CPU through couple of buffers but it is consistent and not cycling. As LA I only have a Saleae 8 clone, but should do the job.

Re: [M100] diagnose

If you're convinced it's stuck in a loop, removing all power (including the NiCd) for a time should fix that On 12/14/17, Mauro Pintus wrote: > Thank you Fugu and Brian for the feedback. > > Yes I tried the beep BASIC test with no luck and also the cold start (the >

Re: [M100] diagnose

What is the RESET line into the CPU doing during the loops? Is the RESET stable? The CPU appears to be RESET, heads to the ROM for data but for some reason fails to complete and RESETs itself. No activity on the RAM or LCD would indicate the CPU is not completing the ROM boot. At this

Re: [M100] diagnose

Thank you Fugu and Brian for the feedback. Yes I tried the beep BASIC test with no luck and also the cold start (the M10 and the M100 are almost identical...). I made few other measurements trying to replicate what Brian is doing and for sure the unit is in a loop... In the linked google

[M100] CVX4 / OPL2LPT with M100?

I was just watching a video of 8-Bit Guy on YouTube where he puts together an "OPL2LPT"... basically a parallel port sound board designed to work as an AdLib sound card. He'd previously done a video for the CVX4, a Covox parallel port sound board clone. The OPL2LPT uses the same Yamaha chip as