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NEC TG-16/TE/TurboDuo => TG/PCE Repair/Mod Discussion => Topic started by: Keith Courage on September 03, 2012, 10:38:05 PM
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Here is one I've never come across before. Hu cards work just fine. CD games freeze to a white screen when loading and CD bios screen is jacked up. Anyone have a clue what chip and or area might be the culprit? I know that bad traces or solder joints could be the problem. I'd just like a general idea of where to begin looking.
(http://img829.imageshack.us/img829/108/cimg6815k.html) (http://imageshack.us/photo/my-images/829/cimg6815k.jpg/)
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bad workram
just had same issue on cd dock
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IC106 is the workram in a DUO correct?
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i believe so
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Hmm I just changed out IC106 and it has the same problem still. What is the IC model number?
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not sure
use a logic probe and check the data and addressing lines
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it may be ic906, not sure
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I found the problem. Did the push on top of the IC test and found the one that was causing the issue. Just needed to re-solder the pins to the board.
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do tell
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It was the NEC D78C14GF R28 IC. I went around the board putting a bit of pressure on each IC while turning the system on and off and then checking the CD Bios screen. Putting pressure on this chip made it work so I then resoldered all the pins around it since I didn't know exactly which pin was not making the connection.
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That's a funny fault. I'm guessing most of the time it's just a loose connection somewhere.
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that is funny, cause my parts board doesnt have a 7814 or equiv chip on it, uses all 3 digit part tags and uses the R tag for resistors.
they used the IC tag for chips
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Well, I thought I had this DUO fixed. Worked fine for about a month and now having the same exact issue again. CD games will not load and CD bios screen is all jacked up. Anyone know which IC is the workram? I have been randomly swapping ICs from another DUO I have on hand because I don't know which one is the problem.
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its either IC106 or IC906
106 is CD work ram
906 is system work ram
i think you have a solder joint or trace crack
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(http://junk.tg-16.com/images/sol.html)
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Thanks Steve. I'll check it out. I am betting on a bad trace as well since I got the thing to work originally by pressing here and there across the board.
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a cracked trace at the card slot is common