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[Console Repair/Mod Center / Re: Intermittent Turbo Duo CD reading]

i am 99% sure you dont have another earth ground connected during testing.
IF the ground makes it run then touching the AV jacks shell to ground will work too.
what i found causing intermittent read issues (tracking errors) especially cold is binding in the laser sled due to dirt or dry grease.
that cap will be hard to identify, but if defective should be replaced.

I don't understand your comment about the earth ground.  All I was saying that if I connect earth ground to board ground it seems to work correctly.  If only the TV or AC adapter was connected to earth ground everything would be OK.

I'm pretty sure its not binding of the laser sled because it seems to run smoothly thoughout the full range if I turn the motor manually.  Also attaching an earth ground would not affect a binding problem.  How would I know if it was binding during operation? 

I also have reflowed all the caps on the CD drive end of the board and gave the board a thorough cleaning and it is behaving exactly the same.

I was probing the electrolytic caps for noise and noticed a 200mV 120Hz signal on the two through-hole caps C136 and C163 near the BA chips.  I'm not sure if this is normal or not.

thanks,
Joe

[Console Repair/Mod Center / Re: Intermittent Turbo Duo CD reading]

I only did spot cleaning with flux remover when I changed the caps so I'm sure it could use a thorough cleaning, although my friend is a bit uneasy about the dishwasher.

I checked it some more today and it is actually attaching my scope's ground clip (or any other earth ground) to the board that makes it work.  That should be a good clue, but i don't know what.

[Console Repair/Mod Center / Re: Intermittent Turbo Duo CD reading]

Thanks for all the responses.  Yes, I did replace all the electrolytic caps on the board.

I also think it might still be a cap problem.  There is a ceramic cap on the board that I can put my finger on when its not working and it will make it work (circled in red on attached image. I'll have to check for the designator tomorrow).  I put a scope on the non-ground side and it measures around 2.5V and is pretty noisy (at least 100mV noise).

[Console Repair/Mod Center / Intermittent Turbo Duo CD reading]

Hello,

I've been working on a Duo for a friend and have run into a frustrating issue.  Sometimes it will read discs and other times it won't.  Usually once its working its fine, but after its turned off the next day it will not read discs again.  The disc spins but the game won't load.

here's whats been done to it so far:

1.  Replace all electrolytic caps (to fix audio problem)
2.  Tweaked the pots
3.  Replaced laser assembly
4.  Tweaked the pots
5.  Replaced laser assembly again (first replacement appeared to be used)
6.  Tweaked the pots
7.  Wiggled wires going to laser assembly while it was operating correctly to look for intermittents. (none found)

Unfortunately I don't know if it had the issue before I replaced the caps.

Does anyone have any ideas on what else to try?

thanks