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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: Damion on November 30, 2007, 04:07:08 AM

Title: A1200 1D4 mobo schematic/help needed (fried resistor)
Post by: Damion on November 30, 2007, 04:07:08 AM
Hi all,

Does anyone know where I can find a schematic for this board? I'm trying to find the value of a surface-mount resistor on the back of the board (underside of Alice), at location "E127R."

Any help/comments are much appreciated. (Yes, I fux0red my mobo :boohoo:)


Damion
Title: Re: A1200 1D4 mobo schematic/help needed (fried resistor)
Post by: Damion on November 30, 2007, 05:40:22 AM
OK... I translated this from Russian:

"Reasonably known problem ESCOM-овских of cars (on Commodor-овских it practically was not shown). Strips appear near to colors, in RGB which is established 23 bat and more. It is treated as follows: it is necessary to short-circuit resistor E127R and to clean condenser E127C. Hаходятся on HИЖHЕЙ to a side of a payment, about under chip Alice. If you are not inclined to consider yourselves reasonably qualified for such operation, address to someone to more skilled is better."

:lol:

I've verified this from a few other sources, so (hopefully) it's safe to remove the resistor and bridge the pads.



Title: Re: A1200 1D4 mobo schematic/help needed (fried resistor)
Post by: rkauer on December 01, 2007, 04:18:02 AM
 Can anyone translate the translation?  :-?  :-?
Title: Re: A1200 1D4 mobo schematic/help needed (fried resistor)
Post by: rkauer on December 01, 2007, 04:20:58 AM
 BTW: Ian Stedman have the fixes for this version of M/B in his site.

 Reach it here! (http://www.ianstedman.co.uk/Amiga/amiga_hacks/A1200_Mobo_fix/a1200_mobo_fix.html)
Title: Re: A1200 1D4 mobo schematic/help needed (fried resistor)
Post by: Damion on December 01, 2007, 04:35:36 AM
Quote

rkauer wrote:
 BTW: Ian Stedman have the fixes for this version of M/B in his site.

 Reach it here! (http://www.ianstedman.co.uk/Amiga/amiga_hacks/A1200_Mobo_fix/a1200_mobo_fix.html)


Thanks! Actually, after some further inspection, E127R seems to be OK. I repaired a burned trace on the motherboard (verified continuity between all associated areas), and also replaced a poor resistor on the top of the board. I can't find any other faults, but still no dice. The board works fine except for IDE -- no drives are recognized by the system, and the HD light stays constantly illuminated as long as a drive is plugged in.

At this point I am looking for a new mobo, but (when time allows) I will probably still try to find out what happened. Or, I may cannibalize it to repair my recent ebay acquisition that arrived with a b0rkened PCMCIA port (and the clockport pins on the wrong side).

At any rate -- this was a lesson learned the hard way for me. Even if you check something 4 times, DO NOT trust your judgment after two bottles of Germany's finest. Get some sleep and try again tomorrow. ;-)

cheers

Damion
Title: Re: A1200 1D4 mobo schematic/help needed (fried resistor)
Post by: rkauer on December 01, 2007, 04:47:54 AM
Quote

-D- wrote:
--ZIP--
 The board works fine except for IDE -- no drives are recognized by the system, and the HD light stays constantly illuminated as long as a drive is plugged in.
--ZIP--



 Congratulations!

 You have a de-validated partition on your Miggy!

 Just turn it on and wait for a couple of days (or hours, depending of the size of your hd) and, hey! Presto! you have a fully functional Amiga again!

 But if you don't like to wait so much, give your Amiga to me! I have all the time of the world on my side :-D
Title: Re: A1200 1D4 mobo schematic/help needed (fried resistor)
Post by: Damion on December 01, 2007, 05:37:44 AM
Quote

rkauer wrote:
Quote

-D- wrote:
--ZIP--
 The board works fine except for IDE -- no drives are recognized by the system, and the HD light stays constantly illuminated as long as a drive is plugged in.
--ZIP--



 Congratulations!

 You have a de-validated partition on your Miggy!

 Just turn it on and wait for a couple of days (or hours, depending of the size of your hd) and, hey! Presto! you have a fully functional Amiga again!

 But if you don't like to wait so much, give your Amiga to me! I have all the time of the world on my side :-D


:pint:

Cheers rkauer, I appreciate your positive outlook!

Unfortunately, all partitions are PFS3, and I've already tried another drive, as well as my main one on a spare 2B board. There's definitely a fault in the IDE somewhere. (I'm pretty bummed, but at least all my expansions appear to be fine.)

Title: Re: A1200 1D4 mobo schematic/help needed (fried resistor)
Post by: rkauer on December 01, 2007, 08:10:36 PM
 I have the schematics (really dunno if is for the board revision you have, but...)

 PM to give meh your email adress and I'll send it to u in a snap!
Title: Re: A1200 1D4 mobo schematic/help needed (fried resistor)
Post by: Damion on December 01, 2007, 08:50:45 PM
Cool, thank you! Might come in handy, hopefully I'll get some time to look at it again soon.

Title: Re: A1200 1D4 mobo schematic/help needed (fried resistor)
Post by: rkauer on December 01, 2007, 09:39:53 PM
 Done!

 I had to send the images 2 u in 4 emails (due the size restrictions on your server).

 But it goes!
Title: Re: A1200 1D4 mobo schematic/help needed (fried resistor)
Post by: Damion on December 02, 2007, 08:32:04 PM
OMtehG!!!11!!!!1


IT LIVES!!!

Everything is working exactly as is was before, including my newly acquired Prelude card! SWEETNESS! :lol:

:pint: :pint: :pint:

Whew. I'll tell ya one thing... time for me to get a better soldering gun. Repairing tiny traces with a ghetto-azz radio shack iron is NOT teh fun stuff. :crazy:

(excuse the over-usage of emoticons, but I'm VERY hapy right now)

 
Title: Re: A1200 1D4 mobo schematic/help needed (fried resistor)
Post by: rkauer on December 02, 2007, 09:35:54 PM
 So, what was wrong with the mobo?
Title: Re: A1200 1D4 mobo schematic/help needed (fried resistor)
Post by: Damion on December 02, 2007, 09:57:46 PM
Two bad traces, one fried resistor, and one melted wire in an IDE cable (that took a while to figure out, since the cable looked OK from the outside).

I really thought it was toast, LOL.




Title: Re: A1200 1D4 mobo schematic/help needed (fried resistor)
Post by: rkauer on December 02, 2007, 10:28:16 PM
 A TOASTER in an A1200 is a very rare sight! :-D