A4000 Yellow screen at boot

[drbrain]

Got a A4000 motherboard (and daughter board) the other day...
It was in unknown condition as it's been in storage for a while but worked the last time it was used...heh..

The problem I have is that it shows a yellow screen when it boots...

I've tried with both a A3630 and a A3640, both known working in my other Amigas but both display yellow at boot.
No FastRAM and tested with and without the daughter board.

I only have 16MB SIMMs so I'm currently using one of those for ChipRAM but from what I've read they should work, but may only give 1MB Chip. (tried 4 different ones, still yellow)
If I remove the Chip RAM it displays a Green screen as it should...

All chips soldered to the motherboard so no easy way to test those elsewhere. Kickstart 3.0 and Buster -09.
There has been some battery leakage but it doesn't look that bad. I've removed it of course and cleaned the board.

So what could cause a yellow screen at boot?

:help:

 

[Skellionz]

Not sure about 4000's tbh but isnt yellow screen some kind of cpu error? prob wrong knowing me

 

[drbrain]

It sure is... but both CPU cards are known working so it must be something different...(AA Chip?, Kickstart?, Buster/Ramsey/Fat Gary/CIA?)

Amiga 1200 & 4000 Screen Colours
Colour Black: Opening Screen Initial hardware configuration passed. Initial system software passed. Final initialisation test passed
Colour Red: ROM error, reseat or replace Kickstart ROMs
Colour Green: CHIP RAM error
Colour Blue: Custom Chip(s) error
Colour Yellow: 68000 detected error before software trapped it (software or hardware error)

 

[Justin]

double check the chip ram fella

 

[cosmicfrog]

had a similar problem on my a4000 as the crystal on the cpu board wast soldered on

 

[Kawazu]

Check all the socket chips for exampel fat buster and all the others.
Had the same problem some days ago and i gave them all some smaking and now it works

 

[drbrain]

Guess I have to disassemble my other A4000 to get the Chip RAM from there...

No socked chips except the Kickstart as I said in first post.

The two crystals on the motherboard are socketed.. maybe I should solder them directly to the motherboard....

 

[Bastich]

I used to get that one before Hikey refurbishment my A4000. Previously to this re-seating the chip ram would solve the problem. If it is this then I suspect the problem is the simm sockets or the address lines. Hope this helps.

 

[Tahoe]

Incompatible ChipRAM module, ChipRAM tends not to work too well with EDO modules, don't know if you have any FPM laying around? I find that of the 10 8MB modules I tried to fit as ChipRAM only one or two would work. All others gave me a yellow screen!

 

[drbrain]

I just tried the 2MB SIMM from my other fully working A4000 and that gave a yellow screen as well.
I also tried the 16MB SIMMs in the working A4000 ...
Two worked fine showing 2MB Chip, both double sided...
Two did not work at all... no boot. no color on screen, just black. both Single sided.

So at least I now know it's the ChipRAM modules fault. Could still be traces etc of course...

 

[drbrain]

I looked a bit more at the board around the battery and there is in fact some damage. The lacquer is gone on some tracks so in theory some could be broken.

Could a broken RTC circuit produce a yellow screen?

 

[rkauer]

No, the RTC circuit will only affect the time "storage".

But the battery could leak into the FAST RAM controller and then an iffy contact would cause those symptoms.

 

[drbrain]

A few traces near the battery/memory slots could be damaged from the leakage....
I don't have the tools/skills to fix this so I guess I have to send it to someone for repair...

Will take a few pictures of the card and upload here for judgement...

 

[drbrain]

Finally I've taken a few pics of the motherboard... :roll:

The motherboard changed its color when I cleaned it..
It was dark green before but somehow it must have reacted so it became light green instead.. :huh:
So it might look a lot wore than it is?!

 

[rkauer]

Pour some lemon juice over the affected area , let it act for some minutes and wash with tap water.

 

[drbrain]

Board is now on its way to Hikey... lets hope he can do his magic with it

 

[drbrain]

It's with a tear in my eye that i say this...:crying:

This board seems to have been taken by the Amiga angels as Hikey can't fix it to 100% without a tremendous amount of time/work.
The board boots but neither Zorrocards nor Fast Ram is detected...

R.I.P. and may your remains help other boards live a long and happy life!

:sad:

 

[merlinkv]

Oh! These are bad news my friend.

But don't desperate, maybe you can find a working one here

 

[Zetr0]

@Dr Brain

Before you give up and surrender to the gods, I would suggest the following,

I believe the problem you are having is Buster related, infact I suspect a solder fracture on the Buster (or RAMSEY) IC. If I could suggest a reflow of the chip / socket solder leads before consigning this to the heavens.

A common way to confirm this is to remove ALL memory from the motherboard, including the CHIP RAM and then turn on the device - should all you get is a yellow screen, an early memory assertion failure was trapped before it could discover there wasn't any CHIP RAM -this means Buster and or RAMSEY is playing up.

I hope that helps

 

[drbrain]

@merlinkv
Yeah... I'll have to keep an eye out for one here, preferably a already refurbished one

Luckily this wasn't my main A4000 so I still have one 100% working

@Zetr0
IIRC I got a green screen as I should when removing CHIP RAM. (as I wrote in first post in this thread).
According to Hikey there seems to have been some battery/acid damage to the Buster/Zorro area with broken traces/vias as a result...