A500 gives red screen when booting Amiga Test Kit 1.21

[Loki762]

First, I must admit that I don't know too much about Amiga, as I have always been more to C128/C64 - don't flame me

However, I have bought a A500 that was in a quite rough (mostly cosmetic) condition. It only does have the standard 512Kb CHIP RAM onboard - no expansion slots or other modifications - this is as stock as it can get, I guess. Well, it did have a 512Kb RAM expansion, but there was too much corrosion on that and it gave a "Software Guru" error after ~30 seconds, so I have for now excluded that and the A500 is at least stable when powered up. I don't see any corrosion or damage on the A500 board anywhere.

My A500 is:

312513 rev. 6A
Assy 312510

When it boots up, then it does show the normal Kickstart 1.3 screen. I have tested with some floppies - most of them failing various sorts of ways, but I think this is due to bad floppies. I have though one floppy booting the first part, where it does show the intro or alike, so it seems to be working, except it cannot continue, but I think this could be due to COM1 is for sure broken, as it is missing some pins, so I cannot fully use the mouse or click with joystick.

However, I have downloaded the newest Amiga Test Kit 1.21 and when it boots then it just stops with a solid red screen.

I have tried touching all IC's, but none gets warm.

Is there any good advice on what I can try out to get rid of the red screen?

Do note that I do have a working A1200, as this is where I did write and tested the test floppy from.

[Loki762]

I have now tried resocket U6 (ROM) and put a lot of deoxit in the socket and on the IC legs. As mentioned then I cannot see any corrosion on the board itself and the corrosion on the RAM expansion was due to a leaked battery on it.

However, the red screen is still there. Could this be the IC/U6 itself being faulty? Or should I try and resolder the pins on it?

[Loki762]

I have borrowed another floppy drive, and with this one it can boot Amiga Test Kit v1.21 without any issue. So I guess my floppy drive is worn-out.

Also sometimes it will not boot a bootable floppy and I need to reinsert the floppy multiple times, before it starts reading (and often it complains about read error).

When I have cleaned the drive as good as I can, is there then anything else I can try to get it in shape again?