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Technics SL-1300 wont spin with torque

A

Aaron F

New Member
My technics SL-1300 (MK1) was working as recently as last week, I built a new record cabinet and unplugged the table to move it over to the new one. Now its not spinning properly, when I pull the start lever the lamp turns on and the platter begins to spin, albeit very slowly. The tone arm tries to move onto the platter but there just isnt enough rotation in the platter to move it. When spinning the platter with my hands the tone arm functions properly, the start,auto return, powering off platter. The motor can maintain the speed if I get it started with my hands and there is an appreciably difference in platter speed when I toggle between 33 and 45 rpm settings. If the tonearm tries to auto return it drastically lowers the platter speed and it cant provide enough torque to lower the tonearm all the way, if i slow the platter with my finger it cannot accelerate back to speed. When the motor is engaged I can hear an inconsistent buzzing sound. I opened it up and the fuse does not appear to be blown and I dont see anything obviously wrong. I don't recall any trauma to the table when I moved it but its strange that it was working before i moved it.
Any suggestions on what it could be?
Ive tried working though some of the trouble shooting steps in the manual but i'm a novice with the multimeter and not sure if im checking everything correctly.
 
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I would start by resoldering the contacts circled in red. They connect the motor PCB to the control PCB. Any cracked/cold solder joints there would lead to all sorts of problems.

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Okay cool, ill give that a try. In the manual it mentions a "constant voltage output" that should be between 17~20 when testing TR1 and 4. When I checked with the unit powered on I was only getting a reading of around 6v dont know exactly how to interpret this / if im measuring at the correct spots
 

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So I measured what I interpreted as C2 according to the circuit board diagram(picture attached) with the unit plugged in. Had a read of 5.75 V.
 

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I tested from A to E (picture shown) and cant get a reading on the 20v setting it just says 0. When I move to 2000mv my reading is around 10.
 

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Thanks, sorry novice to the multimeter and schematics. When I change it to the V~ setting im getting readings of about 6V between the same locations as previously mentioned(A&E).
 
yes im in the US.I dont think its multi voltage, at least I don't see anything thing that indicates it is so. The back says it is for 120v power source.
 
I was checking the diodes in the motor and one of the seems to allow current to pass in both directions, could this be the problem? Doesn't really seem to explain the low voltages from earlier though.
 
This would not be good. Did you check the diode in circuit or disconnected? I would only trust diode measurements with one leg of the diode removed.
 
Im at a complete loss. I have replaced the power transformer, the control board, and the motor. I have lubed the spindle and cleaned/ re greases the internal mechanisms.The turntable is still experiencing the same problem its slow to speed up and doesn't quite get to speed. When the platter is spun by hand its dead quiet, bbut when the motor is engaged(both of them) there is a rotational squeaking sound. Any ideas?/anybody want to buy some spare parts off me haha, looks like none of my replaced parts were the problem.
 
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