Got a Pioneer P3A Turntable in for trouble shooting. There are 3 diodes in the motor assembly , tabled D201, D202 and D203, they are imbedded within the coil structure. 2 of the three are shorted the working one measures 0.7V reverse voltage. The legend on the PCB is marked as two diodes in series. There's no markings on the parts them selves. Does any one have an idea what these parts are. Some resemblance to the SVT-2H parts made by Sanken?
Attachments
As the P3 and P3A was produced for the Japanese market only, there is little information available.
I would speak to a friendly Pioneer Authorised Service department and ask if they have a manual available for you to view.
They look like either position sensors for the speed of rotation or maybe damping diodes.
They cannot be measured in circuit as the coils will skew your readings.
Was the motor faulty or was the drive waveform incorrect I wonder.
I would speak to a friendly Pioneer Authorised Service department and ask if they have a manual available for you to view.
They look like either position sensors for the speed of rotation or maybe damping diodes.
They cannot be measured in circuit as the coils will skew your readings.
Was the motor faulty or was the drive waveform incorrect I wonder.
Thank you Jon. Luckily I have a working P3A as well which is how I located the shorted diodes by comparing the two while running. There are no available schematics for these as all the Exclusive products were only serviced in Japan by Pioneer themselves. The dual series Diode symbol are used in a few places on the PCB however the other part on the main PCB are different in appearance than the ones located in the motor. I have removed them which is how I was able to determine that two of the three are shorted, the working one measures at 0.7V. Symptoms are that the motor does not spin at all. Signal to start does output from a 4013, but a 1.2V signal does not return from motor which is set by the 3 dual diodes.
