Finally picked up one of these units... went for a TLS866a from overseas, knew it was a clone as there is no legitimate source of the A/CS models anymore.
Right out of the box, I was getting read errors (writing is not a problem) on W27C512 and Atmel AT27C512Rs (from a legit source) when trying to read or verify.
Self test fails 9 out of 10 times, with GND 4/ZIF 4 coming back as a fault. I've looked at Radioman's schematics, but I am not exactly on the level of probably 90% of the people here when it comes to rework (nor do I have their confidence).
If it was a constant error, obviously I would think a bung component or dodgy soldering being a culprit, but I can get it to pass the self-check about 10% of the time.
So I turn to your collective wisdom and ask, where do I start looking to try and track down the issue?