DUO Problem

[Keith Courage]

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.

[thesteve]

bad workram
just had same issue on cd dock

[Keith Courage]

IC106 is the workram in a DUO correct?

[thesteve]

i believe so

[Keith Courage]

Hmm I just changed out IC106 and it has the same problem still. What is the IC model number?

[thesteve]

not sure
use a logic probe and check the data and addressing lines

[thesteve]

it may be ic906, not sure

[Keith Courage]

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.

[thesteve]

do tell

[Keith Courage]

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.

[Drakon]

That's a funny fault.  I'm guessing most of the time it's just a loose connection somewhere.

[thesteve]

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

[Keith Courage]

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.

[thesteve]

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

[esteban]