Please help troubleshooting dead Amiga 500 caps blinks fast

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I have a few Amiga 500s with various issues I am trying to work through and bring back to life.

The first on is a rev5

The power light comes on
The floppy sounds like it kicks in
But nothing happens
The caps lock light is flashing fast with no pause. I don't think it is giving the 1-4 code

I don't see any changes to the screen as far as dark gray light gray or any colors

I've tried reseating the chips.

The keyboard works fine in a know good 500

It appears to respond to an a CTRL+A+A but starts flashing right away again.

[MoreBITS]

A little more info...

I swapped the fat agnus with a known good one.

I noticed if I moved the machine around a little bit I would get some noise on the screen.

The noise would be fast scrolling horizontal blue or red lines, occasionally both colors.

A couple of times I was able to get a solid red or solid blue screen.

But then it stopped showing anything on the screen again.

I thought maybe the power connector might be loose so I reflowed the solder on all the points for the connector, as well as the video port.

The above colors are happening more consistently now. If I leave power to the board for a while and then cycle power I can somewhat consistently get solid red.

I have swapped all the chips starting with the cup and made my way around, until I got to the CIA chips.

I noticed the ODD CIA was a little warm, so I swapped it. No change.

Then I swapped the EVEN CIA since it was the last one left to swap just to see if anything changed.

Now I am getting a red screen initially, then a sold green screen.

Power light has 10 short flashes and 1 long. Caps has stopped flashing.

[mech]

It sounds to me like you have bad chip ram. check for any ram chips getting warm,although many times its a open and they won't get warm.

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Update, Thanks Mech, looks like you were absolutely right.

I was looking into the ram, and found that many of them were warm.

Most of them in fact. I thought it would be strange for several to go bad at the same time.

I decided to take one of my trap door memory expansions and remove and socket 4 of the chips so I could test 4 out of 16 at a time from the faulty 500 using the trap door mem in a working one.

I removed all 16 chips from the faulty board and began testing.

Right away it wouldn't boot with the first four swapped into the trap door.

I decided to go for one at a time.

The first 8 I tested failed to boot.

I started wondering if they weren't compatible with each other, but the 9th one worked.

In the end it appears that I have 12 out of 16 bad ram chips.

In the process I did fix one of the other three. It had one bad ram chip that was getting hot. I put a socket in that location and also used it for testing.

Is it possible to boot the 500 with only trap door ram? If I do the chipmem hack and boot it with no ram on the board, but a working trap door 512k board, would it work?

[Hypex]

If you can remap the chip ram to the trapdoor ram I don't see why not. But I've never seen this configuration.

I had an A500 with similar symptoms. Took it to the shop. Didn't play up. It was my PSU destroying everything and was left at home! They must have had it for almost a week before the "native" PSU was tested!

[MoreBITS]

I will give it a try tonight.

If it was a psu that blew these up what if anything else should I expect to be damaged?

[MoreBITS]

No dice, still get the green screen. I don't think I have enough sockets to do the whole board so I will have to wait for them to come in to test it further.

[Hypex]

My A500 developed a very annoying problem. It would randomly reset. Working on a document. Writing a tracker module. Doing assembler. Suddenly, boom, it resets and I lose everything!

So my PSU still provided power but randomly would cause a disruption that would reset the machine. Eventually I found my keyboard was damaged as the caps lock stared flashing and the PCB had to be repaired. Or replaced.