A1200 green screen

[Snoozy]

Arghh!

Ok so i opened my a1200 to remove my cf card hard-drive (was going to transfer some files to my other a1200) anyways when i come to re-install the card and switch on i get a green screen.

So i check all the chips are well seated and the cf is correctly connected and it is so what have i done?

Green screen normally means chip ram error, which chips are these on the mobo and how did i upset them from such an operation? :confused:

I honestly don't think i will ever open my a1200 up after this, how can they be so tempermental :cry:

Anybody got any ideas how i revive my a1200?

[dougal]

Bit of an obvious thing to say and I'm sure you have done it, but did you try disconnecting any trap door expansions, external drives etc..?

[bbond007]

not much help but:

remove everything from the 1200's mb, accel (even the floppy cable) , hopefully you get purple kickstart screen, then start adding stuff back...

sounds silly, but mine has done unexplained stuff like that before refusing to boot.

in every case so far its come back from the dead with that procedure.

[Snoozy]

hey dougal,

yep i tried that first. MY aca1230 has been disconnected - i wanna keep that safe from my dying 1200.

Next i tried removing the 3.1 roms and reverting to my old 3.0 roms and no boot - i think a black screen. So back to 3.1 roms (which i bought new) make sure all legs are connected to rom socket and rom chips are fitted correct order and displaced to the right in the socket...

Change PSU, no difference.

Still green screen, i see the chip ram is soldered in so difficult to change that, is my rev 2b deceased? :confused:

How do i check whether the chip ram is working ok, since green screen points to chip ram, unless i'm missing something here..

Just seen your comment bbond, i will try that tomorrow

[dougal]

I can't think how you could check the chip ram. Did you check for any leaking caps, maybe you can see some residue on the board near the caps ?

Other then that I'm stuck, maybe somebody more technical can help you out or else you may have to replace the motherboard. Hope that's not the case.

Good luck

[bbond007]

hey dougal,

yep i tried that first. MY aca1230 has been disconnected - i wanna keep that safe from my dying 1200.

Next i tried removing the 3.1 roms and reverting to my old 3.0 roms and no boot - i think a black screen. So back to 3.1 roms (which i bought new) make sure all legs are connected to rom socket and rom chips are fitted correct order and displaced to the right in the socket...

Change PSU, no difference.

Still green screen, i see the chip ram is soldered in so difficult to change that, is my rev 2b deceased? :confused:

How do i check whether the chip ram is working ok, since green screen points to chip ram, unless i'm missing something here..

Just seen your comment bbond, i will try that tomorrow

oh, wow sounds like you really already remove about everything...

If the a1200 motherboard itself is connected to a known good power supply with good +5 and does not come to the purple workbench animation and there is nothing visibly  damaged or missing on the motherboard then it is definitely way beyond my repairing skill level

[Gazbonk]

I blew the Chip Mem in my A500 & the 0.5 meg  expansion in the trapdoor slot in 1987, sent it to an authorised Amiga repair center they replaced the chips on the motherboard & I bought a new trapdoor expznsion.
When booting the screen only displayed white then grey & after green.

Take a look here at the Self Test Output paragraph two second bullet point  http://www.amigahistory.co.uk/selftest.html

Good luck

[Merc]

I'm no hardware guru, but I think the green screen can appear (as one might expect) from problems with the Agnus chip in AGA (Alice?) and/or the traces between it and the chip mem.  Not much you can do about the chip if it's soldered on, but maybe the board has a flaky connection somewhere and a bit of *gentle* flexing in the area might help.  If that's the case though it's likely to not be very reliable unless the fault can be repaired properly.

Maybe some small metal filing found its way into an inopportune spot on the board as well -- you never know...

[Snoozy]

Thanks for your suggestions, i took the 1200 apart down to its mobo only and then plugged in - still the light green screen. :confused:

How do i know if its the caps that have blown or whether its the chip mem - or whether i damaged some of the traces - esp near the roms when i was changing them! How easy is it to repair traces (not easy i'm guessing)

My dad is a chartered elec engineer so i could ask him to take a look at christmas but i'm guessing he will roll his eyes at having to look at a 20 yr old computer. And i expect he need the circuit diagrams.

Which are the caps that frequently blow on the 1200 mobo and where would i buy replacement caps? Would faulty caps give a green screen?

[Snoozy]

ok so i had all the smd caps replaced on the 2b mobo (around 13 in all) and................ still green screen. Which didn't come as much of a surprise considering each smd cap that was removed was checked on a caps meter and was found to be functional and within tolerances.
 
So...removal of roms and very close inspection reveals damage to the traces directly under the roms...caused by my (fairly careful) previous removal and reseating of the roms. These traces were repaired and finally purple kickstart screen loads ( i had forgotten it takes nearly 8-10 secs from switch on for the purple screen to appear)
 
Anybody else with this problem i would advise you (very carefully) remove your roms and have another look at the traces there on the circuit board, especially under the plastic edges of the rom socket. This is one of the areas most frequently accessed by a1200 owners when switching between 3.1 and 3.0 roms (or reseating)
 
Oh well at least my 2b mobo has been recapped during the process of finding the fault ....no more removal of the roms for me
 
Hopefully i can get my 1200 back together again and get my aca1230 reinstalled.
 
Good luck to anyone else who ever suffers the misfortune of the green screen.