amiga 4000 not displaying picture

[Karlos]

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?.

Do you see the colour directly from the A4000's built in video port and if so, which colour(s) do you see? It could be that you are seeing one of the hardware failure diagnostic displays:

Red : ROM error
Blue : Custom Chips error
Green : Chip RAM error
Yellow : software failure without trap

[Karlos]

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

Flicker, or alternate between bright and dim in a regular cycle for a few seconds?

[Karlos]

im 90% certain that there rom chips have failed.

Most ROM initialisation failures should result in the "red screen of death".

Are there rom chips different in an amiga 1200?

As far as I know, yes.

[Karlos]

Ok, can you check your system motherboard? Make sure you check the area around the battery and also check for leaking capacitors. The batteries in A4000's are notorious for leaking after all these years.

Make sure you earth yourself before probing around in there. You don't want to add ESD to whatever malaise is affecting it presently.

[Karlos]

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.

When you said the display flickers on moving the mouse, if the hardware was broken I wouldn't expect that.

Can you get a shot with a camera or something?

I wonder if it has booted into a displaymode you can't see properly.

[Karlos]

I used my amiga 1200 just to check and monitor ok

I'm sure the monitor is fine, I'm actually wondering about the settings on your 4000.

What happens if you power on from cold whilst holding down both mouse buttons for about 30 seconds?

Do you get into a working early startup screen?

[Karlos]

no m8

It goes dark then a light grey again

The thing is, light grey is what you'd expect from all the initial hardware tests passing.

[Karlos]

How long did you let it sit at the light grey screen?  With no hard drive attached, I seem to remember it taking 30 seconds to a full minute before a 1200 would throw up a Kickstart screen, can't remember if a 4000 would do the same thing.

IIRC, the 30 second delay was introduced in Kickstart 3.1 to allow for slow-to-spin-up drives attached to IDE on the A1200. As the A4000 also has an IDE interface, it's possible it does the same thing. Having never owned one (*sniff*) I can't say for sure. Certainly my old KS3.0 machines would think nothing of showing the insert disk animation after a couple of seconds whilst the hard drive was still whirring up.

[Karlos]

thats why im sure it might be rom chips but has you said it goes red if they are gone.
I have had the amiga for 3 days and i had to take out the both ide hard drives because it was not displaying properly only showing mixed up colours.  When i had no hard drives connected it did show the disk insert at first but since trying to use other hard drives i have not been successful since then.

Ok, so without any hard disks attached, you get the regular insert disk animation. That's a promising sign at least insofar as it indicates your ROM, Custom Chips and Chip RAM are OK at least. It doesn't preclude a problem with your IDE interface, but we need to clear out a few possibilities first.

Are you trying to boot from hard drives that already have an AmigaOS installed from another Amiga model (eg an A1200) ?

Unless the install is absolutely vanilla, this might fail in one of many different ways and even if it is vanilla, there are differences in the configurations between a fresh install on say an A1200 and an A4000.

Which version(s) of AmigaOS do you have? I would recommend starting off by booting from an original Workbench 3.0 or 3.1 floppy disk as appropriate (with no hard drive attached).

If that works, attach a hard disk and boot again from floppy and see if you can access the hard disk once it has booted. If so, it might just be in need of reformatting and reinstalling.

[Karlos]

hi m8

no its not booting now just only stopped booting since yesturday so something as failed

I'm trying to be systematic here. If you can see the insert disk animation, your core hardware is still working. You may have problems with peripheral hardware, such as a dead hard disk, or IDE interface.

So:

Step 0: Power down the machine*
Step 1: Remove all hard drives from the system.
Step 2: Insert a bootable floppy disk, preferably Workbench 3.0 or 3.1 (whichever version goes with your installed kickstart version)
Step 3: Power on the system and tell us what happens...

*this step included to avoid any litigation potential :lol:

[Karlos]

it just hangs with a grey screen?.

Is there any floppy disk activity at all?

hi m8

Its not reading there workbench disk all hardrives are disconected

Leave the workbench floppy disk in the drive for a couple of minutes and reset. If there is no activity after that time, see if you can read the workbench floppy disk in another machine, assuming it is compatible.

[Karlos]

workbench disk is ok in my amiga 1200 so i think my amiga 4000 is nackerd m8

Ok, but I don't think your A4000 is *completely* knackered, not if it will show the insert disk animation. Whatever is wrong with it would seem to be fixable at this stage.

What is the full specification of your A4000 system? RAM (motherboard, chip, accelerator card, zorro), ROM version, OS version?

Is it using an accelerator and if so, what kind, which processor and what speed?

Other expansion cards?

A full breakdown of the hardware might enable someone with more experience of this model to help you.

[Karlos]

hi m8

Just letting u know i have found there problem, both rom chips where put in wrong sockets an i think that was my fault for messing with roms (shrug) thanks for trying to help me, much appreciated

thankyou

Well, in the end I wasn't much help. I'm surprised the misplaced ROMs didn't give you the red screen though :confused:

In the end, nothing tops this for improperly seated Kickstart ROMS:

[Karlos]

hi pal

One other question if i put a picasso 2 into there system would most games work?.

Various Zorro graphics cards have options to pass through the native video. As far as I know the Picasso II is one of them - however, that doesn't mean it will automatically perform any mode promotion. You'll still need a 15kHz capable monitor.

[Karlos]

Just an addendum, if you are going the Picasso route, I'd recommend trying to get a Picasso IV (unless you already have a Picasso II).

I'm a bit hazy on the details these days, but I recall that the Picasso-II is a Zorro-II only card. It will work, but it places limits on how much fast ram you can have in the system before it ceases to be possible to map all of the card's memory in to the Zorro-II space, after which it falls back to using a segmented memory layout which is very slow.

Furthermore, Zorro-II is slow anyway. Believe it or not, but your motherboard Chip RAM has a higher bandwidth as far as writing from the CPU is concerned.

The Picasso-IV supports more memory, will run in Zorro-III mode, has a faster/wider blitter and equally supports pass through of native modes.

Hopefully someone with the hardware can confirm this, as I said, I am a tad hazy.