I recently cleaned up and restored to working order a Sony PS-LX520 linear tracking turntable. After that it played beautifully until two nights ago when I turned it on and found the "start" control to be unresponsive. As it turned out, the lights that normally come on to indicate speed and playback mode were also dead. It had been playing beautifully the night before.
The only sign of life was from the power button and the light bulb that is used to tell the turntable how big the record is. The table motor was trying to run, turning the platter very slowly. No part of the control panel works.
I popped it open and had a look inside to see if I could find anything obviously wrong. Nothing was obviously distressed. There are three different boards: one for audio, one for the logic control and a power/speed control board. Power comes into the unit from a multi-tapped transformer, and this seems to be OK. Markings on the logic circuit board seem to indicate that there should be -16 volts, +16 volts and +6 volts from the speed control/power board. I have the two sixteen volt supplies and they are very close to being dead on. The six volt supply is completely missing! Most of the connectors are point to point wiring, with the wires placed into plastic guides and soldered to the board. As they look difficult to remove, I have not attempted to see if something is loading down the +6 volt supply. Nothing is getting hot.
I have a service manual coming. Already I have been looking at the two filter capacitors on the power/speed control board. They are both 25 volt,1000uF units. One holds its charge nicely and long after power off. The other one discharges much more quickly, but not quickly enough to make me think that a problem is draining it.
Every date code in the unit suggests it was made around the middle of 1987.
Has anyone worked on this turntable or a similar model and seen this problem?