A500 Plus blinking keyboard LED

[Astral]

I've got an A500+. It had a consistent constant green screen followed by a reset that I managed to fix by removing and cleaning Agnus and socket.

Now I get the first grey screen after the initial black screen and the keyboard LED blinking 10 times followed by a longer blink as it resets. This repeats. I have swapped CIA'S, tried a different kickstart, and checked the two iffy looking traces near the removed battery (looks like very very little leakage has occured) which test ok. Checked for warm chips. Reseated other chips and so on.

I've found numerous bootup error guides but none that help.

I am wondering what might help to diagnose the problem? What can I try? What can I test?

 

[Watson]

I had an Amiga in the past that had similar symptoms, and it turned out to be bad ram on the motherboard.

 

[Astral]

Interesting. When I pulled the Agnus I slipped and bent some of the end pins. I carefully moulded them again and the shape *looks* good. But, perhaps, there isn't proper contact being made?

I assume some of the Agnus lines go directly to the RAM chips? So even though I cleaned the Agnus it still may have a fault?

How did you diagnose the faulty RAM?

 

[Pinback]

i had a look at my collected error codes for amigas and 10times blinking and then constantly on is only existing for the power led, but the meaning is quite interesting:
10 Short + 1 Long Blink (with Green Screen) - Faulty Agnus Chip (try clean and re-insert)

faulty ram is best checked with a diagnosis rom like diagrom. i dont know, if it´s able to point you to the specific faulty ram chip, but it would be the first thing i try.

do faulty ram chips get hot?

 

[Watson]

Some ram chips could get hot when faulty, but in my experience the ram chips on my Amiga remained cold.

I purchased replacement ram and swapped them out testing the Amiga each time until it booted.

@Astral This was way back in the day before diagrom existed, or that I knew of. So yeah, good point, Pinback

 

[Astral]

Interesting pinback. I did read that elsewhere. Thing is, I don't get a green screen.

DiagROM hey? I suppose that's a Kickstart ROM that bypasses/changes the normal check procedure and then does it's own hardware reading/writing to help find faults? That might help.

I think I'll also try seeing if there is a schematic somewhere that I can use to check continuity from each chip to Agnus to help narrow down the area of the problem (as the error may still be related to the Agnus area).

 

[Astral]

Some ram chips could get hot when faulty, but in my experience the ram chips on my Amiga remained cold.

I purchased replacement ram and swapped them out testing the Amiga each time until it booted.

How did you diagnose to conclude even trying replacing the RAM? Or did you just "guess" and went for it?

 

[Pinback]

@Watson : thx, good to know they can also get hot

@Astral
i could burn a diagrom for you, but i guess until it arrives on the other side of the planet, you better get it somewhere near you. the rom is a musthave.

 

[Watson]

How did you diagnose to conclude even trying replacing the RAM? Or did you just "guess" and went for it?

A friend suggested it could be the ram, so purchased new ram and swapped them out. This was back in the days before diagrom's existence.

I would try diagrom , as Pinback suggested.

 

[Astral]

Thank you peeps. I'll consider my options.

 

[Astral]

Sooooo...I ordered and fitted a DiagROM. All I get now is a black screen. If I refit the original Kickstart it goes back to the 10 flashes/reset. And the same with a Kickstart 1.3 ROM. The DiagROM works fine on another 500 I have.

Any ideas peeps?

 

[Pinback]

well, diagrom can output its logs via serial connection. but you need additional adapters: https://sites.google.com/one-n.co.uk/amiga-guides/diagrom-serial-output

afaik, diagrom shows a black screen when not enough chipram can be used (i.e. enough chips are damaged). i would change the chipram located onboard. you can even piggyback the chips to have a quick look.