amiga 4000 not displaying picture

[amiga4000freak]

hi to every one on this site

I only joined two days ago and i have a problem with my amiga 4000 rev b motherboard.  Its not displaying anything only a couple of colours?.

Does anyone have any clues to whats causing this because i have checked the monitor lead and monitor on my amiga 1200 and both work fine:confused:

Much appreciated with any help

[amiga4000freak]

hi

No graphics card just using aga graphics an showing no display when i was trying to boot it into workbench using floppy disk.  Can these machines be set to default like a pc?.

[amiga4000freak]

I did get green colour at first then i got a dark colour with purple lines

[amiga4000freak]

im getting nothing m8 just dark lines with no hard drive attached

[amiga4000freak]

It has worked before on this monitor.  There powe light on the amiga does flicker slightly?.

[amiga4000freak]

hi m8

There power light is ok now still getting no picture thou its gone all together, what are there custom chips?.

[amiga4000freak]

sorry m8

not loading from floppy an im getting a purple screen

[amiga4000freak]

If i plug there mouse in there screen flickers when i move there mouse around

[amiga4000freak]

im 90% certain that there rom chips have failed.

Are there rom chips different in an amiga 1200?

[amiga4000freak]

Is that there graphics chip?.
Also can it be repaired it looks like its there same has my 1200 chip set
Could i use a graphics card instead?.

[amiga4000freak]

battery was removed by previous owner and there is no sign of any leaks of acid, the board is very clean

[amiga4000freak]

It did work at first but it was not displaying all colours when i attached my amiga 1200 hard drive 3.5 an only got a few colours since then it has been showing a grey screen.

[amiga4000freak]

I used my amiga 1200 just to check and monitor ok

[amiga4000freak]

no m8

It goes dark then a light grey again

[amiga4000freak]

already done that a few times no change m8