Hi everybody, long time reader here, but first post.
I'm trying to fix a Onkyo C711 CD player which I picked up off Ebay for cheap. I replaced the belt of the eject mechanism and it has worked fine for years.
Recently it has started to have problems: during play every 3-5 min it skips a bit, with no audio for maybe 0.5/1s and then playing again ok for a while. This happens on different CDs, no matter of which track.
I have opened it and seeing no obvious mechanical problems I decided to have a look at the waveforms in the optical unit, as shown in the service manual on page 15.
The eye pattern looks quite ok, maybe on the weak side (around 1Vpp) but apparently still within the specs. But the Focus Error and Tracking Error look completely out, I see the waveforms centered around 2.1V where they should be around 100mV / 0V resp. according to the manual. Can it be that those signals are so way off and the player still somehow works?
As I am new to optical pickups, before starting turning pots and messing up things I decided to hear your suggestions.
The CD player is built around the common KSS-240A optical unit.
Service manual is about 6Mb so I cannot attach it here, I uploaded on dropbox
https://www.dropbox.com/s/o4fvlnoltgj4ypt/C711_SM_ONKYO_EN.pdf?dl=0