Troubleshooting STFM with white screen

[rubber_jonnie]

It’s the version uploaded by rubber-jonnie. After the white screen it the n shows a couple of lines of text TOS version, whether the floppy is connected and the amount of RAM. After a few seconds it drops into the desktop.

Yes, the checksum won't match what the diags have on record, so as long as it boots you will be fine, just don't expect the ROM checksum test to pass.

[Slartibartfast]

Thanks, good to know.

I’ll try the idea of using a remote terminal to get the diagnostic cartridge to check the keyboard. Does the test involve manually pressing each key?

In any event, I reckon need to disassemble the keyboard now and work out why so many keys don’t work.

[rubber_jonnie]

Thanks, good to know.

I’ll try the idea of using a remote terminal to get the diagnostic cartridge to check the keyboard. Does the test involve manually pressing each key?

In any event, I reckon need to disassemble the keyboard now and work out why so many keys don’t work.

Yes , you have to manually press each key to test it, and with the remote terminal you can still run the tests using the remote keyboard, so you should be able to launch the keyboard remotely, then press each key on the ST to see which ones work, and they will appear on the remote terminal.

[Slartibartfast]

Thought I would post a brief update on my progress.

I haven’t done much to the keyboard but I was able to test my floppy drive in another machine as it works fine so it looks like a fault on the motherboard.

Any likely candidates? I was wondering if it could be the WD1772 disk controller?

[exxos]

The YM2149 controls the drive selects for the drive. If that chip never selects drive A or B then that can be a issue.

But IIRC the 1772 should still drive the MOTOR ON signal. So see if that pin on the 1772 ever changes.

Check the CS pin and see if the 1772 ever gets selected.

[Slartibartfast]

Quick update and this is beginning to look like a mare of a job regarding the keyboard.

Took it all apart today and found out that the reason why so many keys don’t work is that it’s obviously had some sort of drink spill on it in the past and it’s corroded parts of the board.

I think I could jumper most of the corroded tracks but in a couple of places the corroded track goes right up to a graphite pad and I’m not sure if I will be able to solder close to it without damage.

Also, judging from the poor soldering near the two coils, I think somebody has had a go in the past.

Unless anybody has a bright idea, I think I may be looking for a replacement keyboard.

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[rubber_jonnie]

I'd suggest you get a fibreglass pen and clean up the corrosion with that first.

It'll give you an idea of the total damage to be repaired, but be gentle with it.

I suspect that if you use 30G kynar or enamelled wire you can get very close to the pads, though I'd suggest a magnifying glass or microscope to help you get in really close.

Once repaired a thin covering of conformal coating will make it safe and secure for you to close up the keyboard.

[Slartibartfast]

Thanks for the advice. I have some suitable hook up wire but will order up a fibreglass pen.

Wish me luck!