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Old 29 October 2009, 13:35   #1
Dmitry.mry
 
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a1200 yellow screen and many times blinking LED

Hi all. Forgive for my bad English.

I have problem with my a1200

After switch power I see yellow screen and many times blinks LED.
I have disconnected from a motherboard all - the floppy, keyboard, hard drive, accelerator etc. Sometimes (rare occurrence) the computer statup - then I see on the screen the offer to insert a diskette and Amiga logo

I have already learnt from the Internet that it cpu generates an exception. Somewhere also it has been written that many times blinking LED - problems with +5 volt.

How it is possible to find out more precisely, in what a problem?

Thank you.
WBR, Dmitry.
 
Old 29 October 2009, 13:41   #2
DDNI
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Hi Dmitry,
My A120 with A1230 sometimes had this problem. I fixed it by cleaning the Accelerator connector on the Motherboard with a pencil rubber and then Isopropyl Alcohol. be sure to allow sufficient drying time.
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Old 29 October 2009, 18:27   #3
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The problem is caused by one of two causes (if not both!):

- Bad (leaked or dried out) capacitors on the motherboard;

- Not enough "juice" or bad filtered +5V line from the old power supply.

On the first case just swapping the capacitors on the motherboard will cure the problem. It is an inexpensive thing to do and highly recommended, even if the problem is not exactly in there. If they didn't leak yet, they will do in a near future.

As for the power supply problem: toss the original brick away and just keep the Amiga power connector. Hack an AT or ATX PSU with this cable. Problem solved now and for good.
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Old 29 October 2009, 20:50   #4
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I second DDNI's advice about cleaning the accelerator socket and motherboard connector.

I had yellow screens also, which could be cured by a 'little wiggle' of the expansion board (with machine off)
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Old 29 October 2009, 21:32   #5
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Even with nothing connected in the board the guy still have yellow screen. Do you still think is the accelerator connector?
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Old 29 October 2009, 22:15   #6
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If replacing the caps dont work then i would suspect a cold solder joint on the motherboard. I have used a hot air rework blower to reheat all the pins on Agnus and the other IC's to fix similar issues in the past. I would start with Agnus and do one side at a time, its a slow process but if you fix it then it is worth it.
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Old 30 October 2009, 06:14   #7
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I use 250 watt a power unit from PC. Also I tried to connect another, 300 watt a power unit, the same result. I think that matter is not in a power unit.

Capacitors - I too have thought of them. Outwardly they look well, leaked out are not present. You can point, which should be changed? (where they on a motherboard?)

Quote:
Originally Posted by kipper2k View Post
If replacing the caps dont work then i would suspect a cold solder joint on the motherboard. I have used a hot air rework blower to reheat all the pins on Agnus and the other IC's to fix similar issues in the past. I would start with Agnus and do one side at a time, its a slow process but if you fix it then it is worth it.
After breakage I tried to deform a motherboard, to press on chips, taped their contacts, etc., but have not noticed, that it somehow influenced work - no changes existing. If another does not help, I will try to make it.

P.S. I used this Amiga 3 years, it worked perfectly. Then it has sometimes ceased to start up. Then more often. Then even more often (but thus if it was started could work as much as necessary without problems before the first turn off (and can before the first reboot - I do not remember already)) and in the end - has absolutely ceased.

P.P.S. Thanks for answers
 
Old 30 October 2009, 13:47   #8
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Psst!

Oh, only way I know a SMD was leaked is when desoldering it you'll notice the "fishy" bad smell.
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Old 30 October 2009, 14:07   #9
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Many thanks, I will try
 
Old 30 October 2009, 14:15   #10
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Quote:
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This is ZX one of my favorite game !

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Old 30 October 2009, 14:43   #11
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Quote:
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This is ZX one of my favorite game !


A nice amiga conversion exists... My wife loves it
http://aminet.net/package/game/misc/Pssst_AGA_V1
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Old 30 October 2009, 15:00   #12
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oh! thanks DDNI.
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Old 30 October 2009, 18:01   #13
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Old 10 November 2009, 09:23   #14
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**bump**

I'm getting the exact same problem with my newly purchased Microbotics MBX 1200z expansion plugged in. The A1200 is fine when it's not, I do have a spare A500 power unit at my Mothers, I'll give that go as a few people have mentioned it could be the power supply before I try anything else Unless of course it's something stupid like jumpers or something? Hehe.
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Old 10 November 2009, 09:40   #15
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@seuden

Sometimes the top shielding can short out the pins on the expansion.

Have you checked for this/bent up the shielding near the trapdoor slot?

Dave G
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Old 10 November 2009, 09:46   #16
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Hey davideo

Thanks for the tip, I haven't checked the shielding near the trapdoor slot as I am a complete n00b when it comes to Amiga hardware. I'll give it a shot tonight and report back, again thanks for your help.
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Old 10 November 2009, 12:28   #17
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I get yellow screen on my a4000, I`m fairly sure its the crystal on the 030 card as its not soldered on

it came like that

must get a socket for it sometime and get solderin iron out, also try difrent crystals for that oc feeling
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Old 19 November 2009, 12:42   #18
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Quote:
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**bump**

I'm getting the exact same problem with my newly purchased Microbotics MBX 1200z expansion plugged in. The A1200 is fine when it's not, I do have a spare A500 power unit at my Mothers, I'll give that go as a few people have mentioned it could be the power supply before I try anything else Unless of course it's something stupid like jumpers or something? Hehe.
I would do what Davideo mentioned and check the metal sheilding in the trapdoor bay (i usually put some black insulation tape in there ).

I ran that expansion card + hard drive perfectly on the stock A1200 PSU but maybe your PSU has severley degraded over time (not as efficient)? Also double check to make sure none of the plastic jumper caps have fallen off the board! The MBX 1200z was all setup correctly so all you needed to do was plug it in and thats it ... push it onto the connector as far as it will go (without breaking it ).

Here's another thought... I used it with a rev 1D1 motherboard which is apparently the most compatible for using all types of expansion boards, maybe check your board revision and see if it's a compatibility issue?

Please let us know how you get on
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Old 19 November 2009, 12:54   #19
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I haven't had the chance to check out the above recommendations yet but as soon as I do I'll let you know how I get on. Thanks guys.
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