I'm trying to repair a CLD-1750 which a friend gave me. It's in rough shape - and the case screws are missing, so someone's obviously worked on it before. Even so, I'd like to get it going again if I can.

The main fault is that it doesn't recognise discs - CDs or LDs. The pickup head goes through the motions - I can see it try to focus on an LD then a CD - but the spindle motor never spins.
This seems weird to me, because I've worked on CD players in the past and they usually spin the disc a little while they're trying to detect it (I guess that's in case there's dust on the disc).

So far I've checked:

• Laser power output - seems okay, my power meter clocks it at around 0.3mW (300uW) peak when it's trying to detect a disc.
• +14V and -14V SPDL voltages on the power board - both okay and well within ~10% of nominal.
• Power board fuses - all good
• Spindle motor - unplugged this from CN111 and applied +12V @ 1A from a bench supply - motor spun OK.
• Drive transistors, diodes, resistors on the power board (SYPS) - all test OK.

I'm at a loss to explain this one. I thought it might be the power transistors, but they test good. I'm hoping it isn't a failed laser pickup.

Does anyone know what else I could try or check?

I've ordered a new loading belt, just in case - but I can't see how to access that. It looks like the tray needs to come out, then the front panel comes off, but the service manual isn't clear about how to remove the tray.

Thanks!

You need to look at the size of the reflection received back from the disc. If the electronics doesn't receive a reflection back, you should see pulses in the received RF signal is tracking signals, the unit will act as if no disc is installed.