Amiga 600 Boot Problem

[Gary335]

So I recently purchased an Amiga 600 (US) on Ebay, and am having some trouble getting it to boot. When I power it on, it goes to a yellow screen, which flashes red every few seconds. I also noticed that the power light on the system flashes constantly, and the Caps Lock light flashes each time the screen flashes red.

Can anybody tell me what this indicates? My understanding is that the yellow indicates a CPU problem, but the red flash is throwing me off. Any help anyone could provide would be greatly appreciated!

[Gary335]

Have you already done all the obvious stuff? Removed any expansions, reseated the ROM chip, inspected the capacitors, etc.?

Yes. There are no expansions, but I did reseat the ROM chip, and also tried a different ROM chip (the one that was in the system was an older version, the one I want to use is a 3.1 ROM). Capacitors all look good, in fact the whole system looks just beautiful for it's age.

[Gary335]

Flashing red is usually a sympton of a bad onboard memory chip, as I recall. Certainly some kind of hardware issue with exec not starting up properly... so the processor and ROM are probably good.

If you've opened it up already, try disconnecting the floppy drive at either end - could be that that's up the creek. Same with a hard disk.

I guess in theory a bad keyboard MIGHT do it, but on the A600 the keyboard is just a set of switches on a VERY fiddly cable. Probably no need to unplug it, if a switch is bad, it doesn't stop a boot from happening. So leave that alone, for the time being.

Could also be a loose screw, washer or similar, jammed on the board and causing a short. Unscrew the board from out of the case and check. Be careful, the connectors on the back also have little threaded screw headers that also need to come out to examine the board's backside. You need a hexagonal shaped tool or spanner (wrench over the pond) ideally, but pliers will do the job, they just cause scratches.

EDIT: Oh yeah, ROMs. The 3.1 version has to specifically be for an A600. They are not very swappable between Amigas, as a rule of thumb.

Just tried booting without the floppy or keyboard plugged in and I get a green screen for about 3 seconds, then it goes to the yellow with flashing red.

Have not yet taken the board completely out of the case to check on screws, washers, etc. Will take that step next. The ROM chip is for the 600. I originally purchased it for a UK 600 I also have.

[Gary335]

Oh dear. Don't try turning it on again until you've checked everything over visually for something nasty. Like a burst capacitor, or a little bit of metal causing a short cirtcuit.

http://wiki.classicamiga.com/Amiga_boot_error_code_colours

Could theoretically be the power supply, too, I guess. Check the voltages it's giving out with a multimeter.

But, could be just the old ROM is dead and the new one works fine.

http://www.hardwarebook.info/Amiga_500/600/1200_Power_Supply

Checked everything over, nothing seems amiss. Capacitors are fine, everything looks fine. Can't see anything that might be causing a problem. Tried another power supply, same result. So I'm thinking we can rule that out.

[Gary335]

The ROM makes no difference. The result is the same with either one. How would one go about replacing U16 and 17? These appear to be soldered directly to the board. Also, where would I obtain these replacement parts? I imagine I'd have to order them from somewhere on the other side of the pond since I'm in the US?