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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: djkoelkast on May 26, 2011, 08:20:37 PM

Title: Is this A2000 recoverable?
Post by: djkoelkast on May 26, 2011, 08:20:37 PM: Hi all,

So I bought me an Amiga 2000 with a leaky battery. Nice.
Just removed the battery. There is some damage, but everything seems to be fine (I used a multimeter on some of the lines, they seem fine).

Damage is on one resistor and the big networkresistor (I don't know the correct English name for it) and maybe on the CPU itself.
I've cleaned everything I could, but it still looks like it fails to start. I don't know 100% for sure as I don't know if the other parts work.
It does give 1,5 > 1,65 V out of the composite video port, but I don't get an image yet.
I've cleaned the 68000 pins, reseated the kickstart, so I guess there is something else still not quite good.
When I power up the A2000 it does blink the CAPS LOCK once, I thought that might give some hope.

Here are the pics:

Overall:

(http://i.imgur.com/Z1HQ4.jpg)

Damage on the CPU and RP900:

(http://i.imgur.com/YKUUK.jpg)

Damage on the R914:

(http://i.imgur.com/I5UK6.jpg)

Other angle:

(http://i.imgur.com/DdKR0.jpg)

And another:

(http://i.imgur.com/RpDmO.jpg)

What do you guys think? Recoverable or trash the A2000?
Revision number is 4.3

Thanks.
Title: Re: Is this A2000 recoverable?
Post by: Zac67 on May 26, 2011, 08:42:30 PM: The CPU socket is done with and must be replaced. The CPU legs need to be cleaned very thoroughly (fresh solder wouldn't hurt). You'll have to clean up the rest as well - use vinegar to neutralize the battery alkali and scrub with a toothbrush.
Title: Re: Is this A2000 recoverable?
Post by: spaceman88 on May 26, 2011, 08:47:47 PM: Hi,
Did you try your mutimeter on pins 1-5 of the CPU to the bottom of the board? Sometimes the socket will be damaged and it won't make contact.
Len
Title: Re: Is this A2000 recoverable?
Post by: djkoelkast on May 26, 2011, 09:16:44 PM: I removed the CPU, took the pins 1-5 on the slot next to it (looks like a Zorro slot), they connected.

So I cleaned with lemon juice, after that water, after that iso alcohol. Looks a lot cleaner now.

Just tested:

All cpu pins do connect with the underside of the mainboard when the cpu is socketed.

When I turn the thing on CAPS LOCK blinks, tv gives a strange wobble for a brief moment and stays black after that. The floppy drive never starts to "click" for a disk.
When I press CTRL + Amiga + Amiga and release the CAPS LOCK blinks (shorter than when I turn the power on), but no image.

Could it be something else is not right?
Title: Re: Is this A2000 recoverable?
Post by: djkoelkast on May 26, 2011, 10:08:33 PM: After reading this topic:

http://www.amiga.org/forums/showthread.php?t=57873

I think the CPU socket might still be the best bet (as my caps lock also stops working after turning it on/off several times).
Title: Re: Is this A2000 recoverable?
Post by: Plaz on May 27, 2011, 12:28:53 AM: Quote from: Zac67;640452
The CPU socket is done with and must be replaced.

x2, I've repaired several like this over the years. The CPU socket must go. I once made a help video to show how. Wonder if I can find that thing...

Plaz
Title: Re: Is this A2000 recoverable?
Post by: djkoelkast on May 27, 2011, 09:23:57 AM: I've ordered a new socket, so that's on it's way ;)
Title: Re: Is this A2000 recoverable?
Post by: orange on May 27, 2011, 05:43:25 PM: Quote from: djkoelkast;640535
I've ordered a new socket, so that's on it's way ;)

ouch, replacing the CPU socket is tedious/boring/...
I did it once on A2000 but it didn't help until I repaired an 'eaten' track.

I think you should just clean it and then try this:
http://www.amiga.org/gallery/index.php?n=2390

before de-soldering cpu slot.

if in the end you have to desolder (with ordinary soldering iron), don't do all 80 pins at once, save some for tomorrow..
Title: Re: Is this A2000 recoverable?
Post by: djkoelkast on May 27, 2011, 05:58:53 PM: Compare
(http://i.imgur.com/DdKR0.jpg)

with
(http://www.amiga.org/gallery/images/1762/large/1_3754.jpg)

Which ones should connect on mine?
Title: Re: Is this A2000 recoverable?
Post by: Zac67 on May 27, 2011, 06:08:20 PM: @orange
It's 'only' 64 pins, but still a bit of a nuisance...
Anyway, I'd prefer quality sockets (round contacts) over the cheap stock sockets greatly.
Title: Re: Is this A2000 recoverable?
Post by: djkoelkast on May 27, 2011, 06:11:10 PM: (http://i.imgur.com/8ByD1.jpg)

So I guess this might be the problem? How can I fix this?
Title: Re: Is this A2000 recoverable?
Post by: orange on May 28, 2011, 09:44:59 AM: Quote from: djkoelkast;640688
(http://i.imgur.com/8ByD1.jpg)

So I guess this might be the problem? How can I fix this?

sorry, I don't know. you have different board version, so I can't help you. you should take a photo of socket with removed CPU, and also from the underside of board.

IIRC, that last pin on CPU was connected to ROM, so it gave black screen on boot with broken trace, consult the schematics.

you can fix broken traces by using a wire to 'bridge' them, but be extra careful not to connect wrong points..
Title: Re: Is this A2000 recoverable?
Post by: adrian82 on May 28, 2011, 02:11:14 PM: Quote from: djkoelkast;640447

What do you guys think? Recoverable or trash the A2000?
Revision number is 4.3

Whatever you do, please do not trash it!

Also, I recommend having a few spare custom ICs and CPUs at hand to test. There is some Amiga A500/A2000 error diagnosis diagram floating around the internet and usually it helps fixing your problem.

IIRC, a black screen usually means the CPU does not initialize properly. The caps lock LED is controlled independently, btw, as the keyboard has its own 6502 cpu. Actually, the flashing of the caps lock LED indicates errors during diagnosis test.

Adrian