Quoted from zapdbf:I am a tech, i am looking for another tech to help that has worked on these boards before. Here is where i stand with this board.
when the board is idle a9-a10 is active. When i press the test button all address lines become active for a moment then go back to inactive, i have confirmed this behavior with a working board other than the other data lines remain active. It seems to me something is stopping the code and making it return to the stand by state.
I have compared all the eproms to original code and there are no errors. Tested the ram it is good, also have tested the pia 6821 it is good. amp is working. During operation i have checked the logic of all the simple logic ic's, removed the 7445 tested it it is ok. data and address lines seem to be getting to all the ic's. What can i be missing?
Watch the PIA ports going to the DAC when you push the sound test button and compare to a working board. That should tell you if the digital side is working OK.
Newcastle, OK
