I have been given a Technics SL-P1 which does not work properly. The disc motor keeps wobbling back and forth and when I press the open/close button, the disc motor starts rotating at full speed. The display always shows 0000. If I manually open the disc tray, it detects it is open and closes it correctly. If I manually move the pick-up, it detects it is not in the centre and moves it back to the inner position.
I'm testing the player without a disc so I would expect the following:
1) lens starts moving up and down in search of focus (2 or 3 times)
2) no focus found, then stop and wait.
Some older players do start disc rotation during focus search, this might be one of those so I would expect just a couple of spin attempts and then nothing.
What I get is instead (no disc inserted):
1) lens just moves up & down one time.
2) lens is moved all toward one side (tracking coil receives roughly 7 volts)
3) spindle motor starts rotating quickly in both directions (one turn CW and one turn CCW)
If I press eject, the spindle motor starts rotating at full speed, and it can only be stopped by removing power. It behaves the same also if the optical pick-up is completely disconnected (no photo-diodes, no laser, no coils) or if the RF pin is disconnected from main board (the RF DC voltage level is indeed correct at 1.8V). Acting on the focus offset potentiometer moves the lens up & down, but acting on the tracking offset does nothing (I have marked all potentiometers so I can go back to factory settings)
Surely there are tired capacitors but unless one is completely short I do not think they are causing those problems.
I'm testing the player without a disc so I would expect the following:
1) lens starts moving up and down in search of focus (2 or 3 times)
2) no focus found, then stop and wait.
Some older players do start disc rotation during focus search, this might be one of those so I would expect just a couple of spin attempts and then nothing.
What I get is instead (no disc inserted):
1) lens just moves up & down one time.
2) lens is moved all toward one side (tracking coil receives roughly 7 volts)
3) spindle motor starts rotating quickly in both directions (one turn CW and one turn CCW)
If I press eject, the spindle motor starts rotating at full speed, and it can only be stopped by removing power. It behaves the same also if the optical pick-up is completely disconnected (no photo-diodes, no laser, no coils) or if the RF pin is disconnected from main board (the RF DC voltage level is indeed correct at 1.8V). Acting on the focus offset potentiometer moves the lens up & down, but acting on the tracking offset does nothing (I have marked all potentiometers so I can go back to factory settings)
Surely there are tired capacitors but unless one is completely short I do not think they are causing those problems.
