thanks for all the help guys. love this forum. just as reference here is a similar 286 mobo which i found closest physically to mine https://theretroweb.com/motherboards/s/abc-co … ct-286-ver.-1.2
Yes you are right about testing with no cards attached. I removed everything but still same failed result. mobo recognizes i.e. missing bank zero rams or the graphic card (if not present) and makes appropriate beeps but every time I still get the dreaded blinking cursor right after successfully counting the first memory bank.
with or without keyboard connected mobo still stops at the same point, I tried different keyboards (even couple XT keyboards!!!) but mobo seems not to care at all. I reckon if problem is keyboard circuitry related then mobo should at least complain about something?!
I cannot see any jumpers to set for more memory ram. I don't think there is any.
last night I found some corrosions which I had missed earlier: around the area between keyboard to the keyboard controller IC. this weekend I will re-clean the mobo with vinegar and wash with Isopropyl this weekend and attend to any oxidisation on BIOS chips or other chips too.
it's annoying when there is no on-screen error messages or beeps or even then diagnostic card numbers are not helpful
BTW, I am so glad the SIPP rams were so short-lived !!! no wonder. the damn things are so badly designed and are pain to pull out and put back. my finger tips are sore hehe