Green Screen in A500+

[zooliolo]

Recently my Amiga 500+ has developed a green screen on boot. I have found out that this is a problem with the Chip Ram. Can anybody advise me on what to do???? And I don't know anybody who could fix it.

[Akira]

I think green means "Bad RAM", but I can't be sure. Retroman?

[Washac]

Green for Chip RAM..


Hmmm, all I have read states this colour is for Chip RAM.

I think it refers to any memory chip problems....

I recall buying my first memory expansion card for my 500, and had to put the memory chips in myself.

In my exitement to get them in and play Dungeon Master on my newly expanded 500, I put one of the chips in the wrong way round, and my machine locked up at the green screen on boot.

[Overdoc]

Well, a green screen stands for a problem with the chipram, which often is caused by a bad or badly seated Agnus chip.
So first try pushing the Agnus into it's socket to make sure it has good contact. With A-500s it happens quite often that the Agnus has worked itself out of his socket due to termical expansions.

On the other hand, in the A-500+ there is a battery soldered to the board which often starts leaking after some years and can damage some (ram)chips.
But you will notice that as soon as you open up the Amiga...

[zooliolo]

Well I opened it up today and I think I have found the problem. The battery has leaked, but hasn't seem to have damaged anything. Do I just need to replace this and where would i get one from.

Also another matter, if i took the rom out of my A500+ and put it in my A500 would it work?

[Overdoc]

The A-500+ doesn't need the battery to operate !
The purpose of the battery is just the real-time clock.
So I would say desolder the battery before it starts leaking more and check if the Agnus ( 8375 )sits firmly in it's socket.
Also look closely if the leaking from the battery maybe has destroyed some fine traces on the board ?
Then, if you cannot find anything unusual then leave the Amiga on for a short time and feel if any of the ram chips get more hot than others. If that's the case then this would point to a shorted ramchip which could be the problem.

And yes, you can put the Kick 2.0 from the A-500+ into the A-500 without problems if you have a Rev.6A or 8A board in your A-500.
I am not sure about Rev. 3 & 5. I think on one ( or both ) of them you have to connect 2 pins of the Kick 2.0 chip to get it working, but I'm not sure about this.
Maybe someone knows ?

[Shadowfire]

Just FYI I did have this happen to two A500's... it was a toasted power supply that was putting out too much voltage... killed some of the RAM chips on each machine.

[Akira]

Shadowfire
NOT an MS employee



haha, I loved that, Shadow :) I just noticecd it!

[zooliolo]

How would I remove the chip? I don't have a chip remover.
And would removing the battery get rid of the green screen?

[Overdoc]

No, the battery itself is not the problem. But the battery could have caused the problem by leaking and therefore destroying some fine traces of the board in it's area. So inspect the board carefully around the battery if it maybe has leaked and damaged anything !
Removing the battery would be a good idea to prevent further damage, but it will not repair the problem.

The problem is either caused by a bad ram or by another chip that is in connection with the ram, like the Agnus or some chip that is connected with the data bus.
I have an A-500+ which has the 74LS244 at U12 damaged from corrosion from a leaking battery. This one also shows a green screen at startup, but I haven't had enough time to find out what is the cause of the problem.

Also, don't remove the Agnus chip. Just push it down to be sure it is firmly set in it's socket.

[zooliolo]

i have found the problem, a chip next to the battery is covered in green acidy stuff, I have tried cleaning it but it still doesn't work. I suppose I might as well give up.

How would I remove the Kickstart ROM?

[Overdoc]

Ok, then you might have suffered the same thing that my A-500+ suffered. Probably the chip that has been covered by the acid of the leaking battery is the problem.
But I am going to try reparing my A-500+ soon ! So when I find out that this chip next to the battery was broken then that one might also be the problem in your A-500+
I will tell you as soon as I know.

Removing the Kick is no problem since it is always socketed :)
You just need a small screwdriver and then try to lift the chip from both sides alternately until you can easily take it out.
Be careful not to lift it too much from one side only as this will result in bent pins !

[Shadowfire]

Originally posted by zooliolo
i have found the problem, a chip next to the battery is covered in green acidy stuff, I have tried cleaning it but it still doesn't work. I suppose I might as well give up.

How would I remove the Kickstart ROM?

Oh man. Not good. That is dried-up battery acid.

It needs to be cleaned up and repaired by a competent PCB repair shop. At this point just replacing the batter and washing away the acid will NOT fix the machine. Overdocs points are all correct.

Repair now would consist of washing away the acid, replacing any acid-trashed chips (regardless of whether or not they're currently OK since the acid has already gotten to the legs and WILL eventually eat out the inside of the chip), and running bypass wires for any traces that are destroyed. Its much easier to do if you have the schematic diagram.

[zooliolo]

I put the Kickstart 2.0 in my A-500 but it makes it go real slow and I think it is time I salvaged parts off the A-500+ and threw it. I am getting an A1200 anyway. :D

[Overdoc]

I would say it depends on your time and soldering skills. That chip near the battery is a LS244 logic chip which shouldn't cost too much. So you could simply desolder the old one and see if a new one solves the problem. But be sure to check if all traces on the PCB are ok !

Kick 2.0 only makes sense if you are working with the Amiga, but in my opinion it is not a good idea if you just want to play games. The reason is that quite some games don't like the Kick 2.0 and therefore will not run :(
On the other hand there are only some few programs that need Kick 2.0 which will work on a 1MB A-500. Even Crossdos works on a Kick 1.3 machine as long as it is version V5.0 or lower.