A5000 : Initial Assessment

It’s obvious that the Acorn is in bad shape. Last time I booted it up, I got a prompt, now I’m getting nothing.

I’ve done some initial tests and confirmed that I’m getting power from the PSU, to the mainboard, of the voltages I would expect. I’ve also checked the Voltage across the battery and confirmed that is normal.

At this stage and having done some reading, a few possibilities look like good starting points. All of the possibilities relate to the legacy or damage caused by the battery having leaked.

Firstly, the Acorn could be booting and I can’t see the display as has defaulted to a screen setting (resolution and/or refresh rate) that my modern(ish) TFT monitor is very unhappy displaying. I’ve tried holding down ‘DELETE’ on boot-up and also the ‘R’ Key ( which should factory reset the settings), without much success.  Ideally, what I need to do is investigate what the A5000 defaults to for display settings (especially after a reset), and try a couple of different monitors, maybe an older CRT monitor if I can track one down. Also, a possibility might be to build a SCART cable and try it on the CRT TV I do have.

Second, the Acorn could be booting and running, but be faulty in a way that the display does not show anything. Theoretically it should flash the Floppy Drive access LED as a kind of ‘BIOS POST code’, however my Acorn does not have the original Floppy Drive. Quite early on, it became obvious the original drive was faulty, so I simply swapped it for a PC drive, which until now worked fine. It is possible the replacement drive is not showing as the first drive (PC FDD are wired differently with regards to the drive select) and consequently the A5000 is not able to flash the LED. It might not be a bad idea to investigate the drive select and see if I can get the existing drive to produce a status code.

Thirdly, all of the above could be rubbish and wishful thinking. In the end, the old battery has leaked on the mainboard and its highly likely that it has damaged part of the board, which is the root cause of all of the boot issues. I will very likely have to remove the mainboard and visually inspect for damage and clean any residue. Once I’ve inspected the board, I’ll need to repair any obvious signs of damage.

Fortunately, there is a very helpful guide on Retro-Kit (http://www.retro-kit.co.uk/page.cfm/content/Restoring-an-A5000/) which explains some of the diagnosis and repair after just this problem, so I will pretty much follow that and see where I get.

I’d better get my finger out. The halfway point of the month rapidly approaches.

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