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Speed is inconsistent

Hello,

The speed on my SL-BD1 has started to vary up and down. If I try to adjust the pitch at a certain speed, the speed either doesn't change at all or suddenly changes abruptly. If I manage to set the pitch at a certain speed, after a few seconds the speed either drops or goes up significantly. I get the impression that the speed control might not be regulating the voltage properly, could this be the case? Could there be other parts that might be causing this irregularity? Again, I notice that this change in speed happens mostly while, or after, I have tried to adust the pitch.
Thanks.

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  • moran_manuel Feb 16, 2009

    Thanks for the belt tip. Unfortunately the belt is not the problem as it has just been replaced and is not slipping at all. I still suspect it has something to do with the pitch control not working properly but I am not completely sure about this. Any other ideas? Thanks.

  • moran_manuel Feb 17, 2009

    Yes, the platter is spinning freely. The belt is the right size, I ordered it from a specialty dealer specifically for this turntable model and it is the same size as the original was. Thanks.

    Any other ideas?

  • cbond1 Mar 30, 2009

    My sl bd1 works but i now have to "start" in with my finger. the platter that is.. ithought it was the platter but when i took off belt and platter i still had to jump strat the motor.. pitch ctrl is ine once i start hings...any ideas? anyone?

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  • 104 Answers

If it does not brag about being "direct drive" on the front of the unit, then it is probably belt driven
http://www.archive.org/details/Turntable_Belt_Installation
will help you remove the platter to check the belt. if it is slipping it is the most likely cause.

Posted on Feb 16, 2009

  • Steve W Feb 16, 2009

    make sure the platter will spin freely as shown in the video

    if not then the platter would be bogging down the motor.

    also, are you totally sure the new belt is the right size?

    a 1/4" wide belt is often too wide, most belts need to be 3/16" or less in width.

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My father in law gave me a technics sl 1360 turntable he bought in japan in the 60's or 70's. It was boxed up for decades. It cant hold a constant speed. it ebs up and down. any thoughts?


If you can actually hear a change in musical pitch as the speed goes up and down, it's possible it needs to be lubricated. Technics used to sell a silicon oil for this purpose, but no longer. You'll find suggestions for a substitute with a Google search. If you can't hear a change in pitch, but can see the speed variance on the markings around the platter, don't worry. This is normal behavior. What you're seeing is an infinitesimally small amount of change. My Technics 1300 has always done this, especially until it's been running for 10 to 15 minutes. It will even vary between the outer and inner grooves. It's an analog control system and not as "locked-down" as the later digital units, but it's far better than any other non-digital design.

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Recently purchased used Panasonic SL-HM42 turntable. Works, but turning a little slow on 33rpm (30-31rpms) says DC Servo System on the front. Don't see any set screws on bottom. would like to get platter...


How to tweak the playback speed on Panasonic SL-HM42 turntables
recently-purchased-used-panasonic-sl-jxgmd5u3zcskalhaccgps5fw-3-20.png

You will need:

  1. 1x small Philips screw driver
  2. 1x small flat-head screw driver
  3. An ear for correct pitch and a little bit of DIY skill!

Step 1 - Remove the wooden base plate

After ensuring that you've removed the the rubber turntable slip mat and securely docked the turntable arm, carefully flip the turntable over onto its lid to expose the wooden base plate, as per below.

Using the small Philips-head screw driver, remove the screws holding the wooden base plate in place, then gently lift the base plate off the turntable.

recently-purchased-used-panasonic-sl-jxgmd5u3zcskalhaccgps5fw-3-26.png

Step 2 - Expose the pitch adjustment screws

Once the wooden base plate is removed, you will see the speed-controller circuit board on the right-hand side.
recently-purchased-used-panasonic-sl-jxgmd5u3zcskalhaccgps5fw-3-50.png

To expose the the two speed/pitch-control screws, firstly remove the screw holding the speed-controller circuit board in place, then gently lift the circuit board up on the free side.
recently-purchased-used-panasonic-sl-jxgmd5u3zcskalhaccgps5fw-3-41.png

Step 3 - Correct the turntable playback speed and pitch

The easiest way I found to correct the playback speed was to flip the turntable carefully back into the original position, allowing the speed-controller circuit board to hang free as shown below.

recently-purchased-used-panasonic-sl-jxgmd5u3zcskalhaccgps5fw-3-60.png

Next, play a record that you know well and are able to tell when the speed/pitch is correct (assuming you have an ear for correct pitch, that is!), then at the same time using the small flat-head screwdriver, gently turn the speed adjustment screw(s) to adjust the playback speed up or down until the correct playback speed and pitch is achieved (or at least until it no longer annoys you ;).

Turning the screws clockwise (to the right) will increase the speed/pitch, and anticlockwise (to the left) will decrease the speed/pitch.

NB - Both screws allow for fine pitch control, so if the second is already at maximum speed, you can use the first screw for additional speed.
Step 4 - Reassemble the turntable again

When you're happy with the speed of your turntable, remove the record, the mat again & locking the turntable arm, replace the screw holding the speed-controller circuit in place (as per Step 2) and then finally replace the screws holding the wooden base plate, as per Step 1.
Happy listening!

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Try spraying the slider with Servisol Video 40.

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To solve the constant speed problem you'll have to replace the pitch regulator.
Go to any panasonic/technics service and buy the pitch. If you have a bit of soldering skills you'll be able to replace it by yourself. You can access the pitch regulator unscrewing all the screws under the device and then removing the cover.
Hope you can solve the problem!

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If that does not work, your pitch might be bad, or one of the main circuit drive IC's might be bad.

Hope this helps some.

- OPTiC
Master Tech, 1200s.com
Technics Parts : DJ Repair

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