Terrible mistake - bricked A1200?

[xalakibaniou]

I have a stock Amiga 1200 rev 1D4 which does not signal the screen. Actually it does give a signal but I only get a black screen. I caused the problem in my attempt to install an Indivision MK2cr which did not seat properly and after switching the power supply on I realized the Indivision had popped out from the Lisa chip. Since then I get a black screen (with and / or without Indivision) either via composite or VGA PC monitor.


The Indivision MK2cr though works normally on another machine (rev 2b) without problems and image distortions. I would like to know if there is a chance for the machine to be repaired and what do you suggest that I've caused to the machine? I know it's difficult to diagnose without checking the machine thoughtfully with a multi meter or other equipment that I have no experience on how to use or patience to learn .
Finally do you suggest purchasing another mobo or should I give a try repairing the damaged one which is in a perfect condition and and barely used. Which might be more affordable by your opinion, experts?

[Jope]

Look at the lisa carefully. Do you see bent pins? Try to wiggle the pins, do you see any that have cracked solder joints?

[xalakibaniou]

Originally Posted by Jope

Look at the lisa carefully. Do you see bent pins? Try to wiggle the pins, do you see any that have cracked solder joints?

It seems perfectly fine. Should you be able to trace any faulty pins or cracks if i try to take some pictures?

[xalakibaniou]

[Jope]

Nothing seems bent at least. The cracked solder joints are quite difficult to find from photos, but if you want, please take some pictures that look towards the side of the chip so that the solder joints are visible.

[pipper]

The electrolytic caps on your board are leaking. I see green fuzz around the RAMDAC. Get your board recapped immediately! Maybe it’s not Lisa but your ramdac that has an issue.


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[xalakibaniou]

Originally Posted by pipper

The electrolytic caps on your board are leaking. I see green fuzz around the RAMDAC. Get your board recapped immediately! Maybe it’s not Lisa but your ramdac that has an issue. &lt;br /&gt;<br />
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Sent from my iPhone using Tapatalk

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It turns out that the problem is elsewhere. I replaced the 3.0 kickroms with newer 3.1 and boom now I have the so desired promting to insert disk purple screen, BUT after leaving the machine on for a while (15 minutes) I got a yellow screen. I switched of the machine and back on only to get a yellow screen. I get yellow screens every now and then cold and warm boot.&lt;br /&gt;<br />
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I read somewhere that especially A1200 behave like a living organism. I mean you might have 2 extract same configurations that behave completely different&lt;br /&gt;<br />
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PS. I left the Amiga out of the case just the motherboard without anything connected (floppy, keyboard and LEDs). I get the same yellow screen quite often. I am using and Amiga 500 genuine old but stable PSU.&lt;br /&gt;<br />
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Where is the ramdac? How do I locate it?<br />
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I noticed the green fuzz near the surface mounted capacitor next to the composite output. Thanks

[Leon Besson]

First off. Yellow screen = RAM issue.

Second. You are best to get the board recapped before looking to clean up any corrosion (the green fuzz). As that’s been caused by a leaking capacitor.

When recapping, look for any corrosion and clean with white vinegar/lemon juice, then use isopropanol cleaner.

Do this ASAP or you will get other issues with leaking caps!

[xalakibaniou]

Originally Posted by Leon Besson

First off. Yellow screen = RAM issue.

Second. You are best to get the board recapped before looking to clean up any corrosion (the green fuzz). As that’s been caused by a leaking capacitor.

When recapping, look for any corrosion and clean with white vinegar/lemon juice, then use isopropanol cleaner.

Do this ASAP or you will get other issues with leaking caps!

Thank you so much. Even though is pretty much hard to find recaping services in Athens I'll try to.

[Leon Besson]

Originally Posted by xalakibaniou

Thank you so much. Even though is pretty much hard to find recaping services in Athens I'll try to.

Have a look at the sticky threads above to find a good recapper closest to you. Plenty in Europe

http://eab.abime.net/showthread.php?t=88046

[xalakibaniou]

Originally Posted by Leon Besson

Have a look at the sticky threads above to find a good recapper closest to you. Plenty in Europe

http://eab.abime.net/showthread.php?t=88046

Thank you. I appreciate all the help from everyone here.

[Daedalus]

Originally Posted by Leon Besson

First off. Yellow screen = RAM issue.

Yellow screen is an unhandled CPU exception. It could be a RAM issue, or it could be pretty much any of the custom chips or the circuitry in between.

Second. You are best to get the board recapped before looking to clean up any corrosion (the green fuzz). As that’s been caused by a leaking capacitor.

Ideally you'd do (or have someone do) both at the same time, as there is likely damage beneath the capacitors to repair too.

When recapping, look for any corrosion and clean with white vinegar/lemon juice, then use isopropanol cleaner.

The leaking electrolyte isn't necessarily alkaline as it is with leaky batteries - many capacitor electrolytes are acidic, so you can't neutralise it with vinegar or citric acid.

[Leon Besson]

Originally Posted by Daedalus

Yellow screen is an unhandled CPU exception. It could be a RAM issue, or it could be pretty much any of the custom chips or the circuitry in between.


Ideally you'd do (or have someone do) both at the same time, as there is likely damage beneath the capacitors to repair too.


The leaking electrolyte isn't necessarily alkaline as it is with leaky batteries - many capacitor electrolytes are acidic, so you can't neutralise it with vinegar or citric acid.

Oh yeah yellow = CPU exception

http://wiki.classicamiga.com/Amiga_b...r_code_colours

Thanks for the lesson Mang!