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Author Topic: A3640 bad mod?  (Read 289 times)

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Offline bjjones37Topic starter

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A3640 bad mod?
« on: January 07, 2015, 05:58:24 PM »
A few years back I got an A4000 from ebay that work for a few months and then quit working.  I have acquired another since.  I originally thought I had a bad motherboard, but I have since confirmed that the A3640 is bad.  It is a rev 3.0.

I noticed that pin 5 of U200 has been cut off the chip and pad 5 and six shorted together.  I have read about the partial 3.1 upgrade where this is done with pins six and seven but I have found no references to pin 5. Is this a factory mod or did someone just screwup the upgrade? Could this have damaged the board?

Should I try to reverse it?  There seems to be a tiny bit left of pin 5 on U200 that I might be able to jumper.
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Offline Castellen

Re: A3640 bad mod?
« Reply #1 on: January 07, 2015, 11:42:55 PM »
That modification is not correct, the correct modification is documented here.

You can buy new 373 octal latches easily enough if required.  But yes, you should reverse this modification and re-do it correctly.