Hello everybody, greetings from Brazil, this is my first message here.
I'm trying to fix my first CD player made in 1991. It's not portable and not on the topic's list (it's a Gradiente CDP-1000, Brazilian brand) but it's based on Sony design. The main chips are all Sony (CXA1081M, CXA1082BQ, CXD1130, M50930) as well as the optical unit (KSS-210A). In fact the circuit is very similar to the Sony CDP-110, also uses the same ICs for drivers and power regulator.
It was more or less working (playing but sometimes skipping), then after some time in storage it didn't work anymore. The disc was not spinning. After some cleaning and tweaks with the calibration pots (not the laser power at the unit) it at least "tried" to start, but not reading TOC.
After research I decided to replace the optical unit. With the new unit the disc spins immediately, but backwards! I've researched a lot for the causes of this behaviour and could not find my problem. That's how I found this topic.
It spins backwards right from the start, does not reverse rotation.
There is also another strange behaviour (to my eyes), there is some kind of high frequency "noise" or ripple, very stable, on all the signals (+- 5V, RF eye pattern). It seems to be related to the clock generator. It reaches up to 0.1V p-p and appears at the 1us range at the scope. Is this normal? By disconnecting the power source from the circuit (removing jumpers on the board) the power source alone doesn't show this ripple.
I've already replaced most of the electrolytic caps and the motor driver IC and checked most of the solder on the board.
I need to know if the problem could be (only) the optical unit, in this case I can replace for another, of if it may be something more serious or "unfixable".