A500 Rev. 6a GREEN Screen error on Turn ON

[c0dehunter]

I just found an old A500 rev 6a, that I had forgotten in the storage, that I bought along some other A500s years ago.

Decided to connect and turn it on, but all I get is a solid color GREEN screen.

The strange thing is that this system has 1.2 KS ROM chip installed. Is this normal? Should it at least have 1.3? Could the 1.2 be the cause of the GREEN screen?

I really like to resurrect this system, if I could, as everything else seems to be OK (at least visually, all chips seem intact, 512MB chip RAM soldered - traces of another 512 remains)



Thanks for your inputs.

[solarmon]

Kickstart 1.2 isn't an issue in itself - they come with early A500s, but usually on rev 5 and below. Does the A500 have an embossed Commodore logo, and a Commodore logo where the Amiga 'A' keys usually are? And a red power LED?

Do the usual basics of reseating and cleaning the pins and sockets of the socketed chips, using appropriate tools and methods.

Is it stock or does it have any expansions or mods?

[c0dehunter]

The Amiga keys have "A"s on them. I have to turn it on again to see if the ON light is RED or not.

[Vypr]

Green screen on start is a RAM error, either a RAM chip is bad or there are difficulties communicating with onboard RAM.

Things to check are:

a) Does the AMiga have a RAM expansion fitted? The Rev6 Amiga doesn;t have the battery backed up clock like the Rev8 A500+ boards have but the RAM expansion might have one. If there is one present, remove it and try booting again.
A common expansion is the A501 which comes in a sealed metal enclosure, if this is present, remove it.

b) Remove and reseat the Agnus chip. Oxidation can build up on the contacts and cause this kind of error. You will need a PLCC extractor tool. Do not try and use a screwdriver to pry it out, you'll just damage the chip socket.

[solarmon]

Originally Posted by c0dehunter

The Amiga keys have "A"s on them. I have to turn it on again to see if the ON light is RED or not.

This is a later style A500 case, so it is possible/probable that somebody replaced the Kickstart with v1.2

Again, Kickstart 1.2 itself is not an issue that would cause a green screen on a rev 6A.

As stated by Vypr, a green screen is normally memory related - so you need to check the address and data traces going to/from the memory chips.

[c0dehunter]

UPDATE:

I have to say that the KS version was indeed 1.3, and *not* 1.2! (all this time, I mistook the CPU for the KS ROM!)

1) Both POWER and DISK ACCESS (RED and GREEN in that order) light up as I turn the system ON. Now the screen is BLUE!

2) What is the benefit of having an Rev6 system, compared to my Rev 5 anyways?

[DigitalKeeper]

Remove ALL ICs from socket -> check for corrosion and broken Pin's at/in Socket's AND ALL ICs. Clean the Pin's of the ICs -> reseat all IC's and have a look.

Looks like a typical failure of contact Problem's