Revox B226 (CDM-1) stopped working

My B226 has difficulty to start playing a CD. Actually, it won’t start if I do not help it by gently moving the swing arm away from the spindle motor so that it can read TOC and start playing.

Here is how it behaves: when I insert a CD and press PLAY, disc will rotate clockwise for a second or two and then give up. Sometimes after rotating clockwise, it will stop and make a turn anticlockwise and stop. Observing the transport, when pressing PLAY, the swing arm will remain in the innermost position, not moving out of it to search and read TOC. When I press PLAY and move the laser a centimeter from the innermost position, it will begin searching, read the TOC and begin playing. The red laser light and lens movement can be observed.

Further observations and measured data:

Mechanical
- when powered off, the swing arm moves freely and will bounce once or twice when flicked with finger but it prefers returning to innermost position (flex cables)
- no dents or resistance can be felt when moving the swing arm with finger
- in service mode, step 1, the swing arm will not stay in middle position but will return to innermost position despite the offset compensation (-90mV in service mode, step 1)
- when going through service mode steps, swing arm moves faster to inner positions and slower to outside
- when moving to innermost position, swing arm often hits the end with a silent “clank!"

Electrical
- with no CD, offset of the radial motor is around zero V
- with CD inserted, offset of the radial motor is around 500mV in STOP
- in service mode, step 1, radial motor offset is set to -90mV to compensate for flex cable resistance (100mV is recommended maximum)
- swing arm voltages in service mode are symmetrical for same in and out deflections (minus the 90mV offset)
- focus motor voltage is within +/-50mV range in PLAY
- laser voltage is set to 200mV RMS
- focus amplifier is not hot to touch

Thank you in advance for your help.
 

PAM

Member
2002-05-19 9:40 pm
First change all the capacitors and dont forget the 5x 33 uF under the transport. After 35 years they are not really good anymore.
Then adjust the forcus by adjusting the turntable height by the big black Torx screw under the turntable motor
 
Hi PAM and thanks for your response. I forgot to mention that the player was entirely recapped in 2013, including the capacitors on the transport. I also tried to correct the spindle height, first by a quarter and then by a half turn clockwise (upwards) but to no avail. Perhaps I should tr in the other direction.