48K Issue 2 strange lower ram fault
Posted: Wed Mar 17, 2021 7:36 pm
Hi all
Sorry to be a pain with this board but it’s driving me insane.
When I got this board it was in a pretty sorry state, I got a good ULA and I have a Diagnostic rom installed, all the voltages are in tolerance, but when it’s switched on, the diagnostic Rom does a lower ram test, the first time it said it was ok, but each time you turn it on it says random ICs are faulty first it was IC 7, then 10, then 13, if you leave it off for a while it sometimes says it’s ok, then it will say random IC numbers again. All the lower ram 4116s are brand new and all the same batch number. Anyone any ideas? Just to mention, the spider transistor is missing, could that cause it? The ULA is a 5C112E.
Sorry to be a pain with this board but it’s driving me insane.
When I got this board it was in a pretty sorry state, I got a good ULA and I have a Diagnostic rom installed, all the voltages are in tolerance, but when it’s switched on, the diagnostic Rom does a lower ram test, the first time it said it was ok, but each time you turn it on it says random ICs are faulty first it was IC 7, then 10, then 13, if you leave it off for a while it sometimes says it’s ok, then it will say random IC numbers again. All the lower ram 4116s are brand new and all the same batch number. Anyone any ideas? Just to mention, the spider transistor is missing, could that cause it? The ULA is a 5C112E.