Problems with Ctrl + A + A.
 

I can't get my Amiga 500 to reset with ctrl + a + a. When i hold and release the keys, the caps lock LED flashes once.

Any information on what this means and how i could fix it would be greatly appreciated.

Thanks.

This means the keyboard itself is resetting, but that reset signal isn't being passed on to the Amiga. The A500 has a dedicated keyboard reset line in the connection from the keyboard controller to the A500's mainboard. It's worth checking that this is connected properly and isn't damaged. From there, continuity tests on the KB_Reset line might help diagnose the issue. The reset signal is pin 3 of the keyboard connector, and goes to pin 5 of the Gary chip, which in turn tells the rest of the system to reset. There could also be some issue with the Gary chip, but it's more likely an issue between there and the keyboard controller.

If you're not familiar with multimeters and poking around on circuit boards, there are many people who should be able to help you out...

Thanks for the help, i'll be sure to look into it.

Okay, so after checking the voltage of the reset pin on the keyboard connector, it's reading a constant +5v. Correct me if i'm wrong, but it's my understanding that this voltage should dip when i do the reset command.

You mentioned something about the keyboard controller, where would i find this?

Yep, it should dip to 0V to reset the machine, though it might only do it for a fraction of a second so you might not pick it up on a multimeter. Be sure you have the correct pin - the pin beside reset carries +5V to the keyboard...

The keyboard controller is the board attached to the keyboard itself, and more specifically, the large chip on that board. I don't have the schematic for that board so I can't tell you the pins to look for, but it's a fairly straightforward board to check.

I've checked the rest of the pins on the keyboard connector and found something weird. When i hold the reset keys, _KBDATA's voltage drops to 0V. When i release the keys the voltage returns back to 5V. Also, when I do the reset key combination the keyboard no longer works. I tried in Notepad on Workbench and i could type fine until i did the reset key combination.

Does this still sound like something i could fix, or am i going to have to buy a replacement keyboard?

No, that looks normal. When you press the Ctrl-A-A sequence, a special reset sequence is sent to the Amiga, which responds by pulling the KBData line low. This should pop pack up to +5V when the Amiga is ready to reset, at which point the keyboard controller is supposed to put the KB_Reset low. Because the sequence isn't completing, the keyboard communications aren't restarted so it won't work.

There are a couple of thing that could be looked at but you really need a scope or some sort of logic probe to see what exactly is happening. It could still be an issue with the KB_Reset line being broken at some point, but without knowing exactly where the fault is, you couldn't guarantee that a new keyboard would fix it.

Do you know anyone with another 500 nearby whose keyboard you could try? I'm a bit far away in Glasgow, but I'm sure someone nearby could help you out...