Amiga 1000 Orange/Yellow screen at power on

[RSwipe CA]

Hi all,

I wonder if you can help.

I have an Amiga 1000 RevA board. When I switch it on there is the usual 4 flashes from the power LED, then a few seconds delay until I hear the 'boot beeps', the second the sound stops the screen goes orange/yellow and that's where she will sit. No life from the floppy drive, no flashing power LED, nothing on the screen other than a blank orange/yellow page. It will do this with or without the floppy drive, keyboard or mouse connected.

I have removed and re seated all the chips, everything looked fine, the board is very clean with no signs of damage. I also recapped the entire board.

None of what I have tried so far has made a difference, still the same behaviour.


Any suggestions guys?

Faulty chip? Power supply failing maybe? ( I have yet to recap the PSU )

What's your thoughts?

Thanks.

[RSwipe CA]

Thanks guys for your valuable input.

The polarity of the caps is correct. Some of the originals were about 10% off their correct values, but generally all the caps were within tolerances - pretty good for very old caps.

The computer has been doing this since I acquired it.

I have a buddy that 'might' lend me a CPU to swap and try. So it's possible that the CPU is fubar?

[RSwipe CA]

Thanks guys for your valuable input.

The polarity of the caps is correct. Some of the originals were about  10% off their correct values, but generally all the caps were within  tolerances - pretty good for very old caps.

The computer has been doing this since I acquired it.

I have a buddy that 'might' lend me a CPU to swap and try. So it's possible that the CPU is fubar?

Power supply voltages.....

Looking at the power connector Left to Right  Brown/Orange/Black/Black/Red/Red/Grey

With  my NEG terminal of my multimeter on the Left Black pin I get.......  Brown -5.03v / Orange 12v / Black (NEG PIN OF MULTIMETER) / Black 0v /  Red 5.15v / 5.15v / Grey 3.26v

[RSwipe CA]

Sorry. It's a North American 120v system.

[RSwipe CA]

Don't know which Amiga 1000 you have. They are either 120 or 240volts. Here is a picture with a label on the CPU that might help plus both types. Ignore the Spirit.

http://www.scuzzscink.com/amiga/scuzzblog_january18_2/car_sbd_110118_57.jpg

http://www.scuzzscink.com/amiga/scuzzblog_january18/scuzzblogdjanuary18_1103.htm

http://www.scuzzscink.com/amiga/scuzzblog_january18/scuzzblogdjanuary18_1104.htm

Sorry. this one is a 120v North American system. Thanks for your great information. It appears that my PSU is ok?

[RSwipe CA]

You can pick up a spare 68000 or 68010 CPU on ebay for around $5 USD as a test.  

 I have ordered a replacement HD68000P8 CPU from Ebay. I will try the CPU as soon as it arrives and report back.  Thanks for your reply.

[RSwipe CA]

So. The new CPU finally arrived. Unfortunately it has made no difference, it still boots to an orange screen. Would it have anything to do with the display chip? I have fixed issues with old Sinclairs and an Atari 800xl, but this is my first time trying to get an Amiga alive again. Which chips are directly concerned with video output? I am planning on spending a bit more time on this old Amiga this weekend. We will fix it!!!!

[RSwipe CA]

After digging around on the net I stumbled across some info that lead me to the 8361R3 Agnus chip as possibly causing the issue. I was able to borrow a 'tester' and when that was fitted I got the correct boot screen asking for the Kickstart Disk. So, it looks like that's all it was. Now waiting on a replacement arriving. Thanks very much for all your help guys.

[RSwipe CA]

Thanks for the solution. I have an A1000 that I will be attempting to revive later on this year.

No Problem. Good luck!