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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: Amiga_CDTV on March 06, 2012, 05:09:14 PM

Title: A3640 without caps
Post by: Amiga_CDTV on March 06, 2012, 05:09:14 PM
I bought a A3640 CPU-card from eBay. No guarantee was given, but "supposed working". Now that I have received the card, I noticed that the capacitors from the board have been removed, and it seems that some of the solder pads are missing too! :confused:

Is there any chance running the board without the caps? Or fix it... ?

The card is Rev 3.0.
Title: Re: A3640 without caps
Post by: Cosmos Amiga on March 06, 2012, 05:24:54 PM
Pads removed, you need to fix that : http://leblogdecosmos.blogspot.com/2010/07/a3640-incomplete.html
Title: Re: A3640 without caps
Post by: Kawazu on March 06, 2012, 05:39:51 PM
Quote from: Cosmos;682707
Pads removed, you need to fix that : http://leblogdecosmos.blogspot.com/2010/07/a3640-incomplete.html

Great work :laugh1:
Title: Re: A3640 without caps
Post by: J-Golden on March 06, 2012, 06:12:36 PM
Wow Cosmos, that is a sweet fix tutorial you have there.  You mentioned at the bottom that you were going to some other mods to upgrade it to 3.2.  Have you done those yet?  Got any pics?
Title: Re: A3640 without caps
Post by: Amiga_CDTV on March 06, 2012, 06:31:26 PM
Quote from: Cosmos;682707
Pads removed, you need to fix that : http://leblogdecosmos.blogspot.com/2010/07/a3640-incomplete.html


Wow, awesome repair! :cool:

C106's pad is still Ok (naturally, that's the one with most soldering space around it!), C105 and C102 have one pad missing, the last two have all pads missing.

From the pics on the linked thread, I could see some 22uF 16v caps, is this correct and are they all same?
Title: Re: A3640 without caps
Post by: Castellen on March 06, 2012, 07:29:43 PM
Quote from: Amiga_CDTV;682714

From the pics on the linked thread, I could see some 22uF 16v caps, is this correct and are they all same?



The electrolytic capacitors on the board are all 22µF, but the polarity of three of those capacitors as shown on the board silkscreen is incorrect.  This guide (http://amiga.serveftp.net/A3640_capacitor.html) shows how to replace the capacitors with the correct polarity.

I have other information on the A3640 including the upgrade to hardware revision 3.2, listed here (http://amiga.serveftp.net/A4000_HardwareGuide/a3640ref.html).  Essentially it involves replacing U209.  I stock these programmed parts which are available here (http://amiga.serveftp.net/inventory.xgi).
Title: Re: A3640 without caps
Post by: Matt_H on March 06, 2012, 11:46:05 PM
@ Amiga_CDTV

I had a 3640 that was missing one cap. It would boot, but the system would freeze up randomly. With more caps missing/damaged, I'm guessing you probably won't get that far. Amiga Center France fixed it for me (with ceramic caps) and now it's working great.
Title: Re: A3640 without caps
Post by: Vlabguy1 on March 07, 2012, 01:58:48 AM
Quote from: Amiga_CDTV;682704
I bought a A3640 CPU-card from eBay. No guarantee was given, but "supposed working". Now that I have received the card, I noticed that the capacitors from the board have been removed, and it seems that some of the solder pads are missing too! :confused:

Is there any chance running the board without the caps? Or fix it... ?

The card is Rev 3.0.


Too bad you are not in the states... could fix that np...

Rich
Title: Re: A3640 without caps
Post by: mechy on March 07, 2012, 03:33:12 AM
Quote from: Cosmos;682707
Pads removed, you need to fix that : http://leblogdecosmos.blogspot.com/2010/07/a3640-incomplete.html


nice work cosmos, i fix missing pads with thru hole caps too.. works excellent.

Mech