amiga 2000 boot up: random colors and that's all

i got an amige2000 of a friend wha asked me to look at it since it wont boot anymore. And indeed, it wont boot anymor..that is:
when u turn the power on (screen modes are corerct, tested it with another a2000 i have right next to the broken one) the only thing u get to see is fullscreen a random color that changes every 20 secs or so. The only thing that is in that a2000 as addon card is a scsi card with some HD attached to it, bt i already tried to remove it and it's still the same.
Anyone had this also?
What did u do?
What is most likely broken and is it repairable?
(i mean, would i be able to replace the broken part, i have very limited knowledge of the hardware of a2000, it's almost 2 years since i touched mine (i know, shame on me), but i do have some skillz when i comes to HW replacement, and trying to figure out which components are where.)

It's a standard a2000 with workbench 1.2 (at least i think it is, since i havent seen it working, but my friend told me it was that) and no extra ram (except maybe whazt was on the scsi card, but i removed that to keep things simple)

michieman

[blobrana]

Er, Still always good for discos , though!

http://mysite.freeserve.com/blobrana/database/startup.html

Hehe.
DISCO - "Powered by a dead Amiga 2000".

Like it.

[Castellen]

Good idea for the disco

Since the machine is displaying colours, it indicates the CPU, ROM, address
decoder and GFX chipset are all working.
Maybe it's having memory access problems, or problems with talking to Paula?
For a start try reseating all the socketed ICs, including all the chip and fast
memory.

The try swapping a few major components like Paula, Buster, Gary, Agnus with
your working A2000 and see if you get any further.

Failing that, it's disco time!

[pioneer]

This could possibly be caused by corrupted software which is overwriting the chip ram area. Do you have a clear screen during any part of the boot process? Is there a specific point where the screen becomes garbled? Have you tried booting from a floppy? If you have, try booting from a different floppy. Before you can blame hardware as the cause, you have to eliminate software causes. Do you have any fast ram or is it all chip ram?

[KennyR]

I seem to remember that Amigas flash colours on the screen as a diagnostic if something goes wrong and they can't boot. I don't remember the colours and I don't even know if this is what you're seeing.

[pioneer]

The entire screen changes color three or four times during boot. Another thing a novice can check without damaging things. Expansion and contraction when the computer heats up after being turned on and then cools off when it's turned off can cause socketed chips to work loose. This is especially true of such an old computer since it's been going on such a long time. If you firmly push down on a socketed chip and you hear a click or pop, that means it's worked up a little. Of course you have to watch out for static charge whenever you work inside a computer. Pushing down all the socketted chips might help. I reseated all the socketed chips in a Commodore 64 and it solved some problems it was having.

[blobrana]

@michieman
Ok, It was your first post...
Did you follow the link, in my reply?

Did the colours match any thing on the display?

[iamaboringperson]

michieman wrote:
i got an amige2000 of a friend wha asked me to look at it since it wont boot anymore. And indeed, it wont boot anymor..that is:
when u turn the power on (screen modes are corerct, tested it with another a2000 i have right next to the broken one) the only thing u get to see is fullscreen a random color that changes every 20 secs or so. The only thing that is in that a2000 as addon card is a scsi card with some HD attached to it, bt i already tried to remove it and it's still the same.
Anyone had this also?
What did u do?
What is most likely broken and is it repairable?
(i mean, would i be able to replace the broken part, i have very limited knowledge of the hardware of a2000, it's almost 2 years since i touched mine (i know, shame on me), but i do have some skillz when i comes to HW replacement, and trying to figure out which components are where.)

It's a standard a2000 with workbench 1.2 (at least i think it is, since i havent seen it working, but my friend told me it was that) and no extra ram (except maybe whazt was on the scsi card, but i removed that to keep things simple)

michieman

thats a strange error!
any particular colors?
amigas do have color coded error messages, but they dont change from one to the other ~ every 20 secs.
is the monitor cable working? does the machine access drives? it could be the graphics chip
are you booting from anything? it could be a rather strange virus!(the disco virus!  ;-)  )

 :-)

[iamaboringperson]

Ok, It was your first post...

heheh... SEE! some people only reply when its dead necessary!  ;-)

[QuikSanz]

You may also want to check that PSU, it may be getting a bit tired
causing it to reset.

Chris

@blobrana:
i followed your link, but like i said: the colors are random, varying from pink, orange, blue, grey, green

i remember the amiga indeed booting up with light gray, dark gray, light gray (normally) but this doesnt do that:(

also, someone asked if any drives are accessed: not the floppy at least. The HD is spinning up (if connected) but that's all. I also think i remember that a floppy in an amiga normally makes a 'groink'..'groink' noise when there is no floppy in it, but this also not happening.

What is meant by 'talking to Paula' etc? i didnt understand a single word of the names in that post; I think u meant specific components, but i dont know these, like i said, my knowledge of amiga HW is pretty limited

btw, i dont have inet @home, so i can only once or twice a week, (weekends sometrimes more) come back here to see if aznyone replied

michieman..

[alx]

>What is meant by 'talking to Paula' etc?

Paula is the custom chip for sound in Amigas.  They are all named after various people - ie Agnus (has the blitter, copper, addresses memory).  There is more info here.

Then try swapping a few major components like Paula, Buster, Gary, Agnus with
your working A2000 and see if you get any further.

If you can do that, it should help isolate the problem to any particular custom chip - but obviously watch out for those static charges!

[blobrana]

Wow...very strange.
Er what kind of monitor are you using, you said you tested it already? ( try a Television, to test?)
Have a look at any bent pins in the monitor cable (?)

http://www.ntrautanen.fi/computers/hardware/misc/amiga_rgb.htm

Removing everything off the board is good,
And can you boot from another OS ( BORROW ONE).

Anybody else have any ideas...