First post, by tsalat
Hi guys,
another board from the graveyard, I guess, this one is a PCChips/Hsin Tech M216 rev. 1.2 according to https://theretroweb.com/motherboards/s/pcchips-m216. The board does not post anything or make any beeps but some interesting facts after I got the board. The board is in a great visual conditions and there is just a small damage from the battery around the battery with the protective painting damaged but no traces broken.
- the board came with an 10MHz CPU but a 40mHz crystal (if I recall correctly) - i have tried to use a 20MHz CPU but not luck
- I have replaced the OSC with an 50MHz and 25MHz CPU - no difference
- the BIOS was bad, I was not able to read it out - the IC was broken, replaced it but no difference, I have used the BIOS from https://theretroweb.com/motherboards/s/pcchips-m216
- one leg on the IC beyond the socket where the 80287 should be was tear away 74F00N, you can see the solder on the picture
- I have tried different RAM sticks, good ones, no difference, no beep no post
- all ISA pins, adr and data are showing signal but the A28 and A29, Adr 2 and Adr 3, are active at the beginning but then the signal disappears
- the OSC and CLK on the ISA pins is looking fine, the same goes for the OSCs
- the resistivity on all adr and data pins is looking reasonable
- I could not find any other damaged parts
Not sure what to try next but I am curious how the BIOS went bad or why the 74F00N got one leg away. Any idea how to test if the 74F00N is good?
How to verify if the RAM is being considered? Any other idea?
thank you, Tomas