NEC TG-16/TE/TurboDuo > TG/PCE Repair/Mod Discussion

Solved: PC Engine Duo - CD Drive Spins Automatically (Backwards)

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xodaraP:
Hi,
Thank you for accepting my request to join the forum :)

I have recently purchased a PCE DUO and have come across a strange issue. When I power on the console I get the Super System BIOS screen and it immediately says Press Run and the spindle is going as fast as it can, backwards (left)

The motor for the sled is also at full power holding the sled to the left, and the laser motor is holding the laser retracted and also to the left. Powering off and manually moving the sled, it immediately moves back upon powering on

The console had an extreme amount of electrolyte on both sides when I initially received it, and it has had all caps removed and a lot of cleaning before new caps were installed

I have found very little information on this issue but the few YouTube videos and threads I did find suggest this is caused by the vias carrying the +5 next to the 47uF caps at the busy LED - I have tested these and all nearby vias and they all test good for continuity

For reference, the motors are around 6v when the console is powered on, both BA6290AICs are around 7v

Caps were replaced with SMD and through hole as per original assignments. Electrolytics were used not ceramics or tantalums

The issue now is the same as prior to the recap, no improvement post recap

+5 is present across the board. HuCards do play

Console has otherwise not been modified

xodaraP:
This is now solved

For reference, the 4558 op amp at IC107 was bad, and once this was replaced I found the 9V line was flakey. It was reading voltage and beeped out but it was inconsistent. I think the via was barely holding on so so put in a jumper wire and the drive stopped spinning and pushing to one side

Necromancer:
Another one back in happy service!  Congrats!

xodaraP:
Not yet sadly :( about to create another thread for the next issue I have that is proving just as difficult. But I wanted to keep this information here because I have seen a few cases where people have this issue and it is a damaged 5V rail and this was the same issue, but caused by the 9V rail

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