Dead A600 problem

[Harrison]

I installed a 3.1 rom in my A600 and then the system wouldn't work. The screen remained black and the power and Caps lock lights remained on.

Thinking the 3.1 rom could be faulty I tried the original 2.0 rom back in the A600, but the same thing happened. It won't boot to the kickstart screen indicating the system is hanging before or during trying to load the kickstart rom.

At the suggestion of Zetr0 I've just tried the 3.1 rom in an A500 and it sort of works, but with some strange behaviour. When the A500 is switched in the power led flashes and eventually a red software guru message appears, and then the system reboots and the 3.1 insert disk boot screen appears. So the 3.1 rom seems to be working. With some investigation I found out the this behaviour can is due to certain revisions of A500 not being able to handle the 512KB kickstart rom (it can't load the last 256KB from the chip due to the way the socket is wired). Is that correct?

I also discovered that with the 512KB trapdoor expansion removed the A500 with the KS3.1 rom wouldn't work at all. I would just keep flashing the power led and nothing displayed on the screen. But replacing the 512KB trap door expansion (1MB total ram) the A500 started up, guru'd as before and then went to the 3.1 boot screen.

However I did try booting a Workbenchh 3.1 disk in the A500 and it loaded Workbench completely, but as soon as I tried to select the About menu item the system hung with an 80000004 software error. Any ideas? Faulty ram? Or faulty kickstart 3.1 chip?

At least it did prove the chip kind of working in the A500.

Sadly that seems to indicate the A600 could be dead.

I'm going to try the A600's original rom in the A500 next and see if it loads that correctly. I might also try the A500's 1.3 rom in the A600 to see if I get any success with that combination.

[Harrison]

I've now tried the A600's original 2.05 rom (37.300) in the A500 and that worked perfectly. And I also tested booting into Workbench 2 and that also worked perfectly.

That proves the 2.05 rom is working perfectly.

[Harrison]

I've now tried the KS1.3 rom chip from the A500 in the A600 and still nothing.

With all three rom chips (A500 1.3, A600 2.05 and 3.1) the same thing happens. The A600 power light and caps lock lights come on, and you can see a signal is being generated on the monitor, but it remains blank/black. There is no disk drive activity (no clicking) and the keyboard won't reset the Amiga and the caps lock key won't switch off.

This seems to indicate the system can't load the kickstart rom. So maybe a problem with the tracks or solder points around the kickstart socket? I did take a look and couldn't see anything.

[Puni/Void]

Sorry to hear about your problems, Harrison. Hope you'll manage to get it working again.

Have you tried disconnecting the floppy disk drive, HD, and removing the memory expansion? If you try to boot it without all that stuff, it could happen that it would work.

It is perhaps a long shot, but it's worth a try.

[Buleste]

Have you tried cleaning the contacts on the MOBO and also the ROMS?

[Zetr0]

check your PM's H

[Harrison]

Yep, I stripped her right down the naked motherboard! Then tried booting it with just motherboard, rom and keyboard connected, but still the same result.

Will check my PMs now.

[Harrison]

What are the differences between the different revision of A600 motherboard?

I know the first one is branded as A300 on the motherboard and has one extra chip not present in later version (what does that extra chip do?). But what about later revisions?

My currently dead A600 is a 1.3, and looking online I can get a 1.5 replacement. What are the differences between those two? They look identical in pictures. And what changes were made for the version 2 motherboards?

[Harrison]

I think it is definitely a motherboard problem now. It looked like there were a couple of scratches on the motherboard traces underneath the kickstart socket. So to test this out I got a 6B pencil and draw along the traces where the scratches were. On powering up the A600 I got a white screen before it went black again and remained black for all attempted after this.

So does that indicate that I've located the problem? I think the kickstart isn't loading because the traces connecting it to the circuit board have been broken by these small scratches.

I'm heard of circuitwriter pens. Has anyone used one of these, and if so would it work and fix this problem?

[Harrison]

Finally having a bit of time this afternoon I unwrapped the replacement motherboard I got from ebay and swapped them over in the A600. The motherboard I paid for wasn't meant to have a kickstart rom, but it had the older 37.229 rom fitted anyway, so I thought I would leave that one in the socket to first test the motherboard worked.

I fired her up and she sprang to life showing the insert disk screen. So I loaded Workbench 2 up to test everything was OK. Once that was complete I thought I should test the 37.300 rom from the original A600 motherboard to see if that was still OK, and that worked fine too.

So finally I thought I would give Zetr0's 3.1 rom in the new motherboard to see if it would work, and although it is a bit slow at initial boot to get to the insert disk screen it works perfectly. I have so far tested booting into Workbench 3 and that worked fine.

So now I have a working A600 again! So it now has kickstart 3.1, 2 MB chip ram and 2MB fast ram. The final step now is to setup and install the 6GB HD and it will be complete.