Amiga 2000 Black Screen Repair Help

[minimojoman]

I am trying to repair this Amiga 2000 with Battery damage and not sure what to do next.

It is a Rev 4.1 board

I have removed and replaced the CPU socket, and have tested x3 CPU's
(I have a new kickstart rom on the way maybe its that)

I have repaired traces from the CPU->Kickstart
I have checked traces from Kickstart to CIA (good)
Voltages seem fine
I've swapped a Daphne chip for the Denise chip (no change)

I damaged two bussed resistor packs when removing the CPU socket, so I have replaced those as well.

What is the next course of action?? Any help is extremely appreciated!

I have the tool to Pull "Agnes" out as well, but no replacement to try as of yet.

When the new kickstart rom arrives I will try that and see if it does anything different.

Help save this Amiga 2000!!! :-D

[arttu80]

Have you tried to set jumper J300 on different position? Especially if you use ATX supply which doesn't have Tick signal, machine won't boot if this jumper is set incorrectly to use AC line frequency. Set it to use VSYNC.

Also you could use J500 jumper to disable real time clock and extra 512kb of RAM, to bypass these for troubleshooting?

[giZmo350]

Welcome minimojoman!

I just went through this 12 days ago and it is definitely CPU/CPU Socket related. My A2000 motherboard had suffered leaked battery corrosion maybe 10/12 years ago. I bought it off eBay that way maybe 8 or so years ago. I cleaned all the corrosion up as soon as I got it and it worked for quit a while but, years later it died again with black screen symptom. I would push and jiggle the CPU until it would post again every so often. I finally got around to pulling the MB again and the corrosion came back (with no battery for 8 years!) and was in the CPU socket pins and underneath too. I replaced the CPU socket and still black screen. I knew it worked before so I didn't bother with swapping IC's. Went straight to checking continuity from CPU socket to every location on the MB. I eventually found the problem using the schematic. I have a Rev6a board. However, the schematic might help on a rev4.1 board.

Here's my related post.

http://www.amiga.org/forums/showthread.php?t=73370

Read carefully as it will give you a hint on how to correctly read the schematic. A link to the schematic is in the post. Print it out to make things much easier and it really helps if you have a DVM with a beeper when checking continuity.

Good Luck and again welcome to Amiga.org!

[kirk_m]

Would placing a DiagRom in the kickstart socket be of help here?

[giZmo350]

Would placing a DiagRom in the kickstart socket be of help here?

As long as the CPU is still functional and has power, I'm sure it would. That's a good suggestion!

[minimojoman]

Welcome minimojoman!

I just went through this 12 days ago and it is definitely CPU/CPU Socket related. My A2000 motherboard had suffered leaked battery corrosion maybe 10/12 years ago. I bought it off eBay that way maybe 8 or so years ago. I cleaned all the corrosion up as soon as I got it and it worked for quit a while but, years later it died again with black screen symptom. I would push and jiggle the CPU until it would post again every so often. I finally got around to pulling the MB again and the corrosion came back (with no battery for 8 years!) and was in the CPU socket pins and underneath too. I replaced the CPU socket and still black screen. I knew it worked before so I didn't bother with swapping IC's. Went straight to checking continuity from CPU socket to every location on the MB. I eventually found the problem using the schematic. I have a Rev6a board. However, the schematic might help on a rev4.1 board.

Here's my related post.

http://www.amiga.org/forums/showthread.php?t=73370

Read carefully as it will give you a hint on how to correctly read the schematic. A link to the schematic is in the post. Print it out to make things much easier and it really helps if you have a DVM with a beeper when checking continuity.

Good Luck and again welcome to Amiga.org!

Thanks for the welcome!  I have already replaced the CPU socket and checked most of the traces, I will definitely read up on your thread tho and see if I missed anything... I'll keep yall updated!

Thanks!

David Rainer

[minimojoman]

So I've checked all traces from the CPU to kickstart, and they are all fine (well at least D(0:15)  I started checking the other traces A(0:17) but they seem a pin off on the CPU side.

When I power on the computer now the screen stays black and then flashes, sometimes garbled and sometimes shows a solid color screen (although not often) sometimes the screen just flashes but remains black.

Still waiting to receive the new kickstart rom, maybe that will fix it... Id be open to using a DiagRom or whatever its called if someone could lend me one id send it back!

[arttu80]

Still waiting to receive the new kickstart rom, maybe that will fix it...

I'm thinking you should also consider ROM socket replacement. It's very rare when ROM itself is at fault. I have rev 6 mobo which had same kind of behaviour so I only replaced this socket and that helped. Did you try pushing on ROM chip while starting machine?

http://www.amiga.org/gallery/images/5165/1_ROM_socket.jpg

[giZmo350]

I'm thinking you should also consider ROM socket replacement. It's very rare when ROM itself is at fault. I have rev 6 mobo which had same kind of behaviour so I only replaced this socket and that helped. Did you try pushing on ROM chip while starting machine?

http://www.amiga.org/gallery/images/5165/1_ROM_socket.jpg

Yea, that's probably a good idea too if it has corrosion around it.

This ebayer sells DiagRoms occasionally but this listing has ended. Might want to watch this seller for another listing.

https://www.ebay.com/itm/Amiga-diagnostics-for-A500-A600-A2000-DiagROM/152932817977?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2055119.m1438.l2649

[minimojoman]

I'm thinking you should also consider ROM socket replacement. It's very rare when ROM itself is at fault. I have rev 6 mobo which had same kind of behaviour so I only replaced this socket and that helped. Did you try pushing on ROM chip while starting machine?

http://www.amiga.org/gallery/images/5165/1_ROM_socket.jpg

I have pressed on the rom while starting, I will replace the socket soon, might have to order a socket, ill look around and give an update.

Thanks everyone!

[minimojoman]

OH MY GOD!  You guys rock, I replaced the rom socket, and it fired up!! Amazing!

Now, the mouse I have isnt working, well it clicks but does not scroll, either the mouse is messed up or it has a problem on the board.  I need to make sure everything works before I put her back together... will a regular serial mouse work on the Amiga? or is it a special amiga mouse?!  Thanks!!!

Super excited!

[Oldsmobile_Mike]

Now, the mouse I have isnt working, well it clicks but does not scroll, either the mouse is messed up or it has a problem on the board.  I need to make sure everything works before I put her back together... will a regular serial mouse work on the Amiga? or is it a special amiga mouse?

You do need to use a regular Amiga mouse, or a USB or PS/2 mouse with appropriate adapter.  When you say "it does not scroll" - are you referring to a scroll wheel (which needs special software to operate) or that it does not move about at all?

[minimojoman]

You do need to use a regular Amiga mouse, or a USB or PS/2 mouse with appropriate adapter.  When you say "it does not scroll" - are you referring to a scroll wheel (which needs special software to operate) or that it does not move about at all?

The mouse wouldnt move at all, but I cleaned the port and all is well!  Have the computer back up and running and now id like to test the PC card!  :-D  

Thanks to everyone who helped!

[arttu80]

OH MY GOD!  You guys rock, I replaced the rom socket, and it fired up!! Amazing!

Very glad to hear that did the trick! One more saved classic Amiga!

BTW, cool workbench you have there! (I mean that wooden one )

[minimojoman]

Very glad to hear that did the trick! One more saved classic Amiga!

BTW, cool workbench you have there! (I mean that wooden one )

Thanks! Yeah I love this desk, it has a wood pullout tabletop thingies on each side right above each drawer, I really like that feature!

Thanks for all the help, my customer was super stoked to get his Amiga 2000 back in working condition! :-D

Pulled out my Amiga 1000 to help with the repair and now I want to setup my Amiga at home in a dedicated spot for gaming!

Also just found the archive of 12,000 disk images that were backed up so ill be having some fun soon :-D