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Panasonic SAPM-31 Mini hifi, Tapedeck motor running all the time

Tapecaptain

Apr 11, 2022
2
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Apr 11, 2022
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2
Hi
I have a Panasonic SAPM-31 mini hifi and the tape deck motor keeps spinning all the time
If I just connect the ribbon cable to PCB That is connected to the motor, it spins continuously

If I change the input it still spins

I have put it all back together with all the belts in place and still
I can play, forward and rewind but the motor never stops when I press stop

This never used to happen so I am not sure if a transistor has failed or a diode
I will really appreciate the help from this forum
Thanks all

Here is the service manual
https://www.manualslib.com/manual/14...-Sa-Pm31p.html
 

kellys_eye

Jun 25, 2010
4,876
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Jun 25, 2010
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4,876
The motor is shown on page 80 (bottom). You will need to check voltages around Q1316 and Q1314 and (maybe) go backwards from there.
 

Tapecaptain

Apr 11, 2022
2
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Apr 11, 2022
Messages
2
Thanks for the reply
The system works and the tape deck works but the motor is continously running until I click the off button
After reading the schematic I can see it is stated that q310 is a motor switch and q309 is a plunger switch
The plunger works fine but the motor is always running
Is it possible that q310 has become faulty
 

73's de Edd

Aug 21, 2015
3,366
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Aug 21, 2015
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3,366
If you check the incoming motor drive signal from uP . . .IC600 pin 43 . . . . . that output port feeds that darlington pair motor power switching transistor Q310, and the tape drive motor will start running . . . .when the TAPE function from the selector is opted upon.
Then the actual mechanical selection / engagement of play / record - - - - - -fast forward - - - - - or . . .rewind actions will result in a tape transport movement, excepting for the STOP mode.
There, any tape movements would stop, but the motor is still running. But, if you were then to switch it off of TAPE mode, the motor would THEN stop.
Synopsis . . . .
If in TAPE mode, motor runs to be ready for command of mechanical transition to play or FF or RW modes . . . .if left on stop mode motor runs . . . . if switched out of tape mode, motor stops.
Check the pin 43 voltage presence and confirm his.
Finally, you said . . .
If I change the input it still spins
If that means that you switched it out of TAPE mode, and found that you had NO base drive voltage coming in from pin 43 . . . . .then expect a shorted Coll-Emitter of Q310.
 
Last edited:

Erstwhile

Apr 12, 2022
43
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Apr 12, 2022
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43
Good answer Edd,
I recall a Pioneer tape deck (1980s era) that left the capstan(?) motor running all the time, but maybe, as you wrote, it was only when the deck was in a particular mode.
 
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