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Technics SL-7 Tone Arm Motor

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Technics SL-7 Tone Arm Motor

Postby CrisUK » 16 Oct 2017 14:50

Hi,

I'm attempting to repair an SL-7 with a tone arm that doesn't move.

Belt is fine as is all the tracks etc... The problem is the motor isn't turning.

I can't find out any info on what voltages I should expect at the motor terminals on the PCB under the dust cover.

I am testing at just over 2v at the moment, seems very low. Could that be my problem?

Any help would be greatly appreciated.

Cheers

Cris
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Re: Technics SL-7 Tone Arm Motor

Postby tckmet » 16 Oct 2017 15:13

check these out on this site. It is a very good table once up and running right, are the plastic lock tabs at the sides intact if so be gentle closing and opening.

instruction/owners manual English

service manual English

schematic English - soundfanlab

brochure English - neeleman
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Re: Technics SL-7 Tone Arm Motor

Postby CrisUK » 16 Oct 2017 15:47

Thanks for the reply.

I've already got the service manual open. I can see the error I'm making with the voltage measurement, the motor is PCM controlled, which explains the low voltage on my meter! I'll go stand in the corner!

I took a bit of a punt and applied 9v to the motor briefly. That seems to have done the trick, something inside the motor must have been seised and the little bump has freed it up.

Now the arm is moving along the track under power, I notice that it doesn't travel all the way to the end stop switch. It stops about 5mm short. Is this normal? It seems to pick up the end of the record regardless.

Cheers

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Re: Technics SL-7 Tone Arm Motor

Postby tckmet » 16 Oct 2017 16:52

You may have the end detect and reset switches confused, look at page 6/7 of the manual and you will see what I mean. The end detect is inside toward the left of the unit and the reset is closer to the spindle, did you also see how they kept the motor away from the arm it is all the way over to the left on the other side of the record. 8) Great engineering in a consumer base item. =D>
Last edited by tckmet on 16 Oct 2017 16:55, edited 1 time in total.
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Re: Technics SL-7 Tone Arm Motor

Postby CrisUK » 16 Oct 2017 16:55

If I had bought this table brand new today, I'd be very happy indeed.

The fact that it's actually from the early 80's just make is even better!

Sounds very nice, bass heavy. Which is good for me :)

Cheers

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Re: Technics SL-7 Tone Arm Motor

Postby tckmet » 16 Oct 2017 16:56

I replied to the switch question and did you know that you can literaly stand the unit up on its side and it will still play since the arm is dynamic balanced instead of static balanced like a radial arm. The SL-QL1 is another great one to have and I am working on 2 of them besides a SL-DL1 and a SL-BL3. I also have several of the SL-Q2s and the 1200mk2s along with 1300/1400mk2s and I finally bought a SP-15 and SP-25 to play with in the future.
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Re: Technics SL-7 Tone Arm Motor

Postby CrisUK » 16 Oct 2017 17:15

Thanks. It is the "End Detect Switch S307" that never gets reached. I am using the cue function to move the arm along the track. Maybe it's just the cue function that doesn't allow it to go that far?

But the machine seems to pick up the end of the record just fine anyway somehow.

They are great machines, I can see why you'd want to collect them!

Cheers

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