I'm trying to fix an old Technics SL-PJ27A, nothing fancy, just a basic CD player from early 90's. It is based on the Philips CDM4/19 mechanism and so far i had little problems with players based on such swing arm mechanism. This player indeed works perfectly with stamped CD, but with CD-R it can have problems: it reads the TOC with no problem, but then when playback starts it seems as if it is not able to correctly lock on the track and the arm is swung back and forth with the head hitting the plastic wall near the spindle motor. Once it locks on the track, it then plays the CD with no issue from start to finish.
I have already replaced the faulty Philips electrolytic caps in the servo board and both laser power and focus offset are correctly adjusted.
What could be wrong in this player ?
thanks
I have already replaced the faulty Philips electrolytic caps in the servo board and both laser power and focus offset are correctly adjusted.
What could be wrong in this player ?
thanks
I vaguely remember this surfacing quite some time ago and I think the problem was the type of the CD-R used but am uncertain - this was at the time of painting the edges of the disc with the idea to reduce internal refractions by the laser, and adding damping discs and magnets to the spindle/clamp, etc, - perhaps you might have a look at the discs used for the CD-R and if that's not the problem, then you eliminated a possibility - the CDM4/19 was a pretty trouble free unit.
I hope this is of assistance ...
I hope this is of assistance ...
Yes, CDM4/19 are typically quite reliable; i tested the CD-R (and other CD-R's as well) in other players, including a CDM4/19 based Marantz and they all read it with no issue.
But actually part of the radial engine servo is managed by the Technics main control IC which drives digitally the radial engine IC on the servo board. This player sports a "fast disc access" and indeed compared to other CDM4 players it is pretty fast in skipping track. Not sure if that might be responsible of over-oscillation in the radial engine servo with some type of CD-R (typically older CD-R's, burned before 2010).
I should take a known good CDM4 and try it on this player, but i do not have another CDM4 that i am willing to risk.
But actually part of the radial engine servo is managed by the Technics main control IC which drives digitally the radial engine IC on the servo board. This player sports a "fast disc access" and indeed compared to other CDM4 players it is pretty fast in skipping track. Not sure if that might be responsible of over-oscillation in the radial engine servo with some type of CD-R (typically older CD-R's, burned before 2010).
I should take a known good CDM4 and try it on this player, but i do not have another CDM4 that i am willing to risk.