One memory card slot not working after soldering to mother board

The slot for the second memory card on the motherboard adjacent the two main chips and the heat sink fan is not working - I had an overheating problem, got a new main heat sink assembly and fan and soldered a jumper wire and loop across HS2 on the board from the top.  The original card in the second slot (adjacent the heat sink devices and the HS-2 slot) did not work when I restarted the machine; removing that card allowed the machine to boot up and operate, although slowly (with only 256 MB).  I replaced the original and second cards with Kingston 1-G cards, but the second card slot does not work either.  Nothing looks amiss from above.  Could my soldering the jumper across HS2 have goofed up something under the motherboard, or is there likely another problem?  Please advise on analysis and repair.  Thanks.
Patent_Atty_ChgoAsked:
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PCBONEZConnect With a Mentor Commented:
Check for solder hairs or droplets. (Bridging a gap.)

Check that you didn't scratch a solder trace/run on the board with something while you were handling it. (Everywhere, not just at the work site.)

Check on the other side of the board from where you were soldering to see if any SMD devices shifted on their pads. (SMD are those tiny things.)

A magnifying glass and a small flashlight can help big time with some of those above.

Clean up the site after the work with isopropyl alcohol (Rubbing alcohol. I use 91% which has 20% less water than 71% and is just as easy to find.) and an old tooth brush, que-tips, or similar. You want no flux left behind.

If you didn't remove the CMOS battery while you were working you might want to reset the CMOS. (And maybe re-flash the BIOS too.)

Motherboards are thick PCB's. You generally want to use a hot iron (40-60 watts) to minimize the time heat is applied. Warming the site slowly over a long time actually allows the heat to travel further through the PCB than using something very hot and getting it over with quickly.
Also want to use small diameter solder. It takes less time to start flowing and thereby minimizes the time heat is applied.

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Frosty555Connect With a Mentor Commented:
How close was the place you soldered to the memory slot? And did you use a soldering heat sink when you did the work to prevent heat damage to the rest of the board?
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Patent_Atty_ChgoAuthor Commented:
The HS2 pins are a good 3/8 to 1/2 inch or so from the memory slot.  I used a very small soldering iron with a pin tip, so unless solder ran beneath the board I can't imagine there was damage by heat; the initial melting of the HS2 pin connections was likely as hot....  I did not use a heat sink on the board, but tinned the wire ends and the sockets to minimize heating duration.  
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nobusCommented:
did the seconfd slot work before you started? if not, it may just have been bad all the time...
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Patent_Atty_ChgoAuthor Commented:
The full memory, both cards, was fine before the system overheated and pulled out the heat sink loop at HS2 on the motherboard.  I replaced the main heat sink and fan and soldered a jumper wire across the HS2 contacts as suggested in previous posts; when the system started up again I got the memory error message, and that cleared when I removed the card in the second slot.  So it was either the system heat or the soldering that disabled the memory slot - a new 1G memory card also did not work when the system started up, but the system works fine with no card in the second slot and a 1G card in the first slot.  Any ideas?  The motherboard must be removed from the case to see the underside - a major undertaking....
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nobusCommented:
it's the only thing to do : inspect your work closely, and double check for shorts; clean it out also (maybe debris fallen in to it..)
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Patent_Atty_ChgoAuthor Commented:
Yes, I worry about where the original 2-pin and loop device at HS2 has gone to - can't find it anywhere in the case!  Thanks.
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nobusConnect With a Mentor Commented:
>>   can't find it anywhere in the case!   <<  you better find it...cause of trouble ahead
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Patent_Atty_ChgoAuthor Commented:
A local technician has advised that 1G of memory is plenty unless I'm doing video editing or such, so I'll not worry about the 2nd memory slot.  Thanks!
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nobusCommented:
that depends on the OS you use; with XP i agree ; but with Vista 2 Gb is suggested...
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Patent_Atty_ChgoAuthor Commented:
Based on what people say, I'll stick with XP for as long as possible!  Thanks again.
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