Really dead A2000 - Video scrolls after booting.

I'm trying to ressurect my A2000 having been stored in the garage for the last 8 years...(yayyy...good luck).

So far I have;
* Removed the battery, cleaned the crud and the mb looks ok - there's no major corrosion around the cpu or surrounding tracks.
* Removed all components other than keyboard, floppy drive and RGB monitor (Philips CM8803) via scart.
* Checked PSU with multimeter. Not sure what I'm doing but there was a 5v (4.8) and 12V (11.8V) on floppy connector when amiga was running. It sounds/ smells ok...?
* My A2000 originally booted to just a black screen. I have an A500 that is a mystery machine too. I tried swapping each chip from my A500 until it produced a result and it got me this far...

All it does;
-Boot screen looks like it just goes to dark grey and then the video appears to roll very quickly (lots of white horizontal lines running down). The monitor is good, I have tested it with another system.
-Keyboard seems to work ok. Cap flashes once. Allows me to reset via three finger solute.
-Floppy is a..flop. It will not acknowledge a disk in drive at all during boot. It doesn't even light up. Can I simply connect the A500 floppy to the A2000 ribbon connector as a replacement?

The motherboard has one hot ram chip that I will replace. I will also try and hook up the ami to composite tv and see if I get any picture.

Other than this, I am at a loss what to do next (get a minimig?). I have some floppy drives that could replace the ami's - but am concerned about the video issue on boot. Could be a component problem.

Can anyone suggest any further troubleshooting?

i recently introduced my kids to amiga games on WinUAE and they were over the moon - getting the A2000 going would be AWESOME.

[nobodyii]

Have you tested your RGB to SCART cable with another Amiga? You need a RGB to SCART cable with some resistors in it so that the CM8803 switches to the right input type.

If the cable is OK:

There is a little green fuse soldered to A2000 mainboard near the RGB connector. I think the fuse (0,4A) is defective and you have to change it.

I've checked the scart cable/ monitor with a working A600 and it works great. It's not that (unfortunately!).

I will check the fuse and try the composite out later today and see how that goes. Thanks nobodyii!

[Loedown]

If one single ram chip is getting hot that could very well be the culprit, getting hot indicates a short circuit and that could be dragging down an address or data line.

Just tried composite out on both our plasma and old school CRT telly and getting similar results.

The dark grey (first) boot screen comes up ok then after about 3secs the display starts to roll with bands running at 30degree angle. The bands do change appearance though like it is running through the boot screen checks but cannot make anything out. I'm being an optimist and hoping thats a pulse.

I'll replace the bad ram chip and see how it goes but thanks to both for your advice so far.

I've replaced the bad ram chip and swapped the floppy drive but this has made no difference.
Still get a dark grey on initial boot then a few seconds later the display seems to scroll/ have bad sync problems.

I have tried removing a single chip (cpu, paula, denise, CIA) to see if I gives me any boot error colours and oddly it just stays on the dark grey.

If I do a soft keyboard reset a white screen comes up for a couple of secs then the display rolls/ loses sync.

I've google-d this so many times and found nothing.

Its bizarre that the display is fine on initial boot but goes bananas after the first system check. Why?

Before I wave the white flag, I would appreciate any last minute advice or things to check before the system is binned or relegated to the garage for another 8 years...

[8bitbubsy]

Did you try to check the fuse that you got suggested? I really doubt it will help, but who knows...
Also, don't throw it away! There's a big chance someone in here can sort out the problem for you, then you'll have a sweet Amiga 2000!

[Loedown]

Originally Posted by dancasper

I've replaced the bad ram chip and swapped the floppy drive but this has made no difference.
Still get a dark grey on initial boot then a few seconds later the display seems to scroll/ have bad sync problems.

I have tried removing a single chip (cpu, paula, denise, CIA) to see if I gives me any boot error colours and oddly it just stays on the dark grey.

If I do a soft keyboard reset a white screen comes up for a couple of secs then the display rolls/ loses sync.

I've google-d this so many times and found nothing.

Its bizarre that the display is fine on initial boot but goes bananas after the first system check. Why?

Before I wave the white flag, I would appreciate any last minute advice or things to check before the system is binned or relegated to the garage for another 8 years...

I can either fix it for you or buy it off you, I'm only down in Melbourne.

Sorry 8bitbubsy - I did check the fuse and it was ok.

There is a strong urge for me not to chuck it but in reality it will retire to my garage of junk...unless I fix it...or the wife finds it and chucks it.

Loedown - I really appreciate the offer for the repair, but getting the box/ mb down there will be a hassle(?). I'll PM you.

[rkauer]

Check the TTL chip very near the crystal. It is hot or (worse) completely cold?

Swap the bugger and try again.

Also move the tick source from PSU to Video sync, those A2000 PSU have a nasty habit of dying for nothing.

@rkauer - Thanks for the tip. I've looked at it but it is neither hot nor dead cold. Yes, I have swapped the tick source jumper but no dice.

From the amiga troubleshooter guide, it appears that anything dodgy with the crystal will result in a DOA system (black screen) so I did not think it was this.

The same guide advises that sync problems may be a busted u205 so I will have a go at replacing that first then try the TTL near the crystal.

[CrashMidnick]

And did you try to replace Denise or push on her ? And check all tracks of your MB.

Was thinking over rkauer idea and thought maybe it was the clock that was faulty.

I picked up another 2000 last week that wasnt booting. The battery had gotten to it pretty bad so I have scavenged it for parts..

Replaced the clock (X1) with the one from the spare motherboard.

Upon booting got a yellow screen straight away (bad CPU) then flicker display. Replaced the CPU with the spare and next boot got a black screen. Checked board while it was powered and noted that I had bent two pins of the 68000...(doh). One pin broke when I removed and tried to straighten it (double-doh). Replaced with original CPU - boot then went Red (bad kickrom) to constant light gray (I think).

Replaced kickrom with spare and this time it would boot up to light grey/ white then reboot. (woot! getting somewhere).

Googled and noted some guy had this problem and had wrong jumper settings. Changed J200 (tick clock) - did nothing so reverted back to PSU timing. For some reason had jumpered J500 previously when trying to repair the memory. Removed and...it BOOTED! WOOHOO!

To say what the source of the problem was is a mystery to me. I think it was a combo of faults due to the box sitting in storage for so long and was only prodded to life after 2-3 weeks of poking, pushing and pulling of chips, jumpers and components.

Not over yet...I found two of three mice that I have, one works only in x-axis whilst the other is in y-axis. The third is in the garage and will test tomorrow. I may be moving on to mouse repair.

Thankyou all for your help...I've noticed that AmosPro and Blitz Basic is still kicking and will give that a go. The amiga is alive.

[8bitbubsy]

Glad to hear that you got it fixed!
Now give it some fast RAM and do the 1MB chip RAM hack. That would be a lovely machine for WHDLoad and programming.
Or give it to your kids and regret that you don't have the cool Amiga 2000 for your own use anymore.