Technics SL-B202 arm pulling back

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viperz
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Technics SL-B202 arm pulling back

Post by viperz » 17 Dec 2017 00:28

Hi all,

I got this SL-B202, which I am really trying to bring back from dead. So far, I rebuilt the motor completely - now it's silent and holds speed accurately, and cleaned all speed control pots.

I tried to test it, and the arm would either slide off the record (when placed on the outer edge of a record), or would stay in one spot (when placed in the groove). This happens independent of the tracking weight (arm is balanced, tried with two different carts/headshells), or antiskate.
I checked under the arm - when set to 1.5g, the antiskate spring only really engages when the arm is approximately in the middle.
I tried increasing the tracking weight (up to 3g on AT95 cart), and antiskating (up to 4), but it doesn't make any difference.

The autoreturn mechanism was stuck, I just cleaned and oiled it, waiting for the oil to sip on all shafts, but I don't think that would Help anyway.

Thanks for your Help

I uploaded a short video to my google drive - let me know if this works please:
https://photos.app.goo.gl/wkXKTxhXbewijgPA3

musicmn
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Re: Technics SL-B202 arm pulling back

Post by musicmn » 17 Dec 2017 00:41

I don't know if it's the video or what. But the platter is spinning backwards. It should turn clockwise not counter clockwise. When you rebuilt the motor did you connect the wires to the motor correctly?

viperz
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Re: Technics SL-B202 arm pulling back

Post by viperz » 17 Dec 2017 01:02

Wow, talk about embarrassment...

The motor is soldered onto the board, so I don't think it could go back any other way, and I only desoldered the 2 leads of the motor to remove it. What the heck did I do...

musicmn
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Re: Technics SL-B202 arm pulling back

Post by musicmn » 17 Dec 2017 01:15

I thought this was the model where the motor was soldered to the board but i just wasn't sure it's been a while since I worked on one. I guess you need to desolder it and turn it then solder it back on hope fully that will get the polarity correct.

viperz
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Re: Technics SL-B202 arm pulling back

Post by viperz » 17 Dec 2017 01:28

The motor can only go back one way according to the service manual. There is an opening on the bottom of the motor, which should go on top of the Hall sensor IC.

The only other thing I did is replace the two electrolytic capacitors on the board - I checked polarity of the caps relative to markings on the board, and it matches.

I removed the motor:
IMG_20171216_192418.jpg
(224.61 KiB) Downloaded 119 times

viperz
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Re: Technics SL-B202 arm pulling back

Post by viperz » 17 Dec 2017 02:27

I switched the brushes inside the motor, OMG...

musicmn
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Re: Technics SL-B202 arm pulling back

Post by musicmn » 17 Dec 2017 02:35

Glad you figured it out.

viperz
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Re: Technics SL-B202 arm pulling back

Post by viperz » 17 Dec 2017 04:13

Thank you for your Help. It's spinning in the right direction now and no problems with antiskating :)

Spinner45
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Re: Technics SL-B202 arm pulling back

Post by Spinner45 » 17 Dec 2017 04:51

LOL! :lol:

Electone
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Re: Technics SL-B202 arm pulling back

Post by Electone » 17 Dec 2017 14:04

Man, I hope you didn't chew up your stylus...

viperz
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Re: Technics SL-B202 arm pulling back

Post by viperz » 17 Dec 2017 15:06

No problems with stylus. But I also didn't hear any weird voices.

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