After fitting a Tynmouth RAM and ROM replacement, as well as new video RAM, the underlying video circuitry on this troublesome 8032 seems to be working OK. The POST sound goes on, but there are no displayed characters. Removing the character chip fills the screen with green rows, as expected.
Where to look next? Barring any evidence or suggestions, I will start socketing the 74-series chips and swapping if available.
(PLEASE IGNORE THE 2.5V PART OF THE THREAD TITLE... After a bit of pondering I realized that 2.5v is awfully close to a signal switching between high and low rapidly, so I pulled out NEWNES' 74-series IC reference and discovered I was measuring the wrong sides of the ICs)
Where to look next? Barring any evidence or suggestions, I will start socketing the 74-series chips and swapping if available.
(PLEASE IGNORE THE 2.5V PART OF THE THREAD TITLE... After a bit of pondering I realized that 2.5v is awfully close to a signal switching between high and low rapidly, so I pulled out NEWNES' 74-series IC reference and discovered I was measuring the wrong sides of the ICs)
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