Turbografx CD unit only spins CDs about a quarter way around before stopping

[wowsux133]

I recently purchased a nonworking TGCD unit and the dock from eBay for around $200 in hopes of repairing it.  I can't test the dock as I don't have the necessary AC adapter yet so I just tested the CD unit standalone.  The gear is fine and will move the laser back into starting position if I move it manually, so I'm guessing it's a issue with the laser being bad.  I ordered a Discman D-33 to pull the laser from but before that arrives I figured I would try to adjust the pots, does anyone have a guide to doing so?  Also both the CD and dock sort of have this burnt electronics smell to them, but from my quick examination I didn't see any burn marks on the pcb boards.  Is this a sign of bad capacitors?

[Ergot_Cholera]

Replace the capacitors first before you touch the pots or laser.

[wowsux133]

How difficult is a full recap of the CD unit?  Even if I don't do it now it's an inevitability with the poor quality of NEC capacitors.

[majors]

Replace the capacitors first before you touch the pots or laser.

Are the CDROM units' caps prone to fail? B/c I've not heard that. I had one on the bench and I the caps ready to replace, but turned out it was just a sticky gear.

... the poor quality of NEC capacitors.

I do not think NEC made caps but instead bought them from suppliers to use in manufacture of their electronic products. To be fair,  I doubt NEC thought we'd still be playing turbo's 30 some years later.

[Ergot_Cholera]

It is worth replacing them due to age, but the 4.7uF caps near the volume dial do tend to leak.

[Keith Courage]

The white pc engine CD drives are way more prone to it than the Black Turbo Grafx CD drives. However there were two types of motherboards for the pce CD drives. One board was prone to it and the other was not. It's easy to tell which is which because the board that does not typically need caps is a light green/yellowish green color where as the board that usually needs caps is the darker green pc engine CD board. The Four 4.7UF caps mentioned all leak and there is also a row in the middle that typically go bad that deal with lens functions. The caps are all in a row 100UF, 22UF, 4.7UF, and 1UF.

I suppose you could just replace all of the caps but I've found sometimes that is not best since the solder points on some of these boards are very week and can be pulled off of the board when trying to change the caps. I've receive many boards like this from people not knowing what they were doing. Makes it real fun trying to re trace/work the connections.

[Slypty]

I've fixed a lot of these boards.  The last one I got actually had a broken switch near where the laser hits the bottom.  You can test it with a multimeter, see if you get continuity when the little black peg is pressed down.  I wouldn't disassemble the switch because the spring in there is microscopic and a pain to get back in.

  Also very possibly a laser problem.  You can contact me if you need a laser, I have a few extra KSS-220a that fit it I can sell.

  I've seen more TGCD boards go bad than PCE, but they were straight from a repair guy at NEC so I don't know what went wrong with them initially.