Recently just acquired a Duo-R, it was known to have disc drive issues, but working HuCard slot.
I figured that at worst, I get a working PC-Engine that just can't play CDs.
Well when I first tested it today after Fedex delivered it, I popped in a pressed music CD, and after hitting Run the CD drive just revved up slowly but steadily up to an extremely fast speed. It never would stop spinning and would endlessly say "Just a Moment..." Opening the lid the disc wouldn't stop spinning either. It wouldn't stop until the system was reset or power cycled.
So I cracked it open, and was pleasantly surprised to find it had been recapped and the board was extremely clean, almost as if it was brand new. Even had the Super Capacitor for the Backup Memory replaced with a 1f supercap.
After fiddling with it for a little while I found the laser sled motor would not return the laser to the center. I later found testing the resistance of the motor, and it was completely open unlike the working motor in my other parts Duo.
So I swapped the entire optical drive assembly from the parts Duo, now the disc drive is behaving more normal. But no discs can be read at all.
It moves the laser to center, and the lens bobs up and down, and the laser diode is illuminated. (Very brightly if I use my Cell phone camera)
Looks like someone else in the past already tried tweaking the pots as they already had marker marking their original positions.
But I attempted some pot adjustments to see if the laser will finally see the disc. No dice. I checked all the values and compared them with values found in this thread, and all seemed normal.
I looked up and down the board around the CD ICs, looking for any bad vias, or traces, or even bad solder joints and making sure all the caps were in the correct polarity.
Everything looks perfect.
I tested the cables for continuity, all passed.
I tried both lasers in the assembly with the good sled motor, both exactly the same response. Return to center, lens bob, diode illuminates brightly, disc nudged a bit by spindle motor once, then it sits for about 10seconds while the laser diode is still illuminated the lens bobs up and down slowly trying to focus the laser, the spindle motor nudges the disc again and then it quits, with the message on screen telling me to "Please Set Disc"
I ordered a new laser, but I am not confident it is going to fix anything. As I've read through this entire thread and found a couple people with the same issue that seemingly never could figure out what was wrong even after installing a new laser.
I read something about some mirror in the laser assembly, and the CXA1081. Chip seems to be working fine but I don't have a scope and have no intentions of ever getting one, so I can't be 100%.
while the system was on, I tried looking for chips that were getting hot. Nothing.
I tried reflowing a couple drive chips, namely the CXA1081, and this didn't provide any change at all in how the drive was attempting to read the disc.
Any help would greatly be appreciated.
