SL-1100 speed issue, 45 stable and solid, 33 fluctuates

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hags
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SL-1100 speed issue, 45 stable and solid, 33 fluctuates

Post by hags » 11 Jan 2012 14:26

Recently picked up a Technics SL-1100.

At 33 1/3 the speed fluctuates. At 45 rpm the speed is rock solid.

What am I looking at here, dirty pots, doing a recap, power switch, resistor out of spec, all of the above?????

Any advice would be appreciated.

Coffee Phil
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Re: SL-1100 speed issue, 45 stable and solid, 33 fluctuates

Post by Coffee Phil » 12 Jan 2012 23:30

Hi Hags,

Your turntable has two speed adjustment potentometers which are selected with a switch. If the machine is stable in 45 RPM it almost has to be the 33 pot. The first step is to spray control cleaner into the pot and work it back and forth. Keep in mind that there is a centering pot for each speed on the board as well. They should also be cleaned.

Phil
hags wrote:Recently picked up a Technics SL-1100.

At 33 1/3 the speed fluctuates. At 45 rpm the speed is rock solid.

What am I looking at here, dirty pots, doing a recap, power switch, resistor out of spec, all of the above?????

Any advice would be appreciated.

Tedrick
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Re: SL-1100 speed issue, 45 stable and solid, 33 fluctuates

Post by Tedrick » 12 Jan 2012 23:41

This is not an uncommon problem on 'tables with pots for adjusting speed, especially older models. Deoxit is your friend.

hags
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Re: SL-1100 speed issue, 45 stable and solid, 33 fluctuates

Post by hags » 12 Jan 2012 23:51

Hi Phil,

Yes, I cleaned both sets of pots as that is the easiest/least costly thing to start with.

No change.

Before I started changing parts or ordering caps for total recap I took some basic resistance readings.
It seems that the SPDT microswitch linked to the 33/off/45 toggle/slider switch has a problem. When switched to 45 there is zero resistance to common, when swtiched to 33 the resistance varied from 200 to about 1.5K ohms dependant upon it being simply switched on or off. I swapped the leads between 33 and 45 coming into the microswitch and instantly 33 is absolutely stable and 45 varies and is very touchy.

I have replacements for both internal microswitches on their way. Newly manufactured parts have a longer rated cycle rate and higher voltage and amps.

All is well.

Thanks!

jpbicknell
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Re: SL-1100 speed issue, 45 stable and solid, 33 fluctuates

Post by jpbicknell » 21 Jun 2019 05:01

hi there! reviving an old thread with the same issue, tried the same lead swap with success... do you have a part number for the replacement switch??

best
Jay

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Re: SL-1100 speed issue, 45 stable and solid, 33 fluctuates

Post by sylvain999 » 03 Jul 2019 00:17

These are pretty standard microswitches, easy to get for a dollar in any electronics surplus. Those ones for speed are the smaller kind while the power one is standard size. Every time i service a sl 1100 i change all of them because they are sealed and get very oxidized inside so they are not easy to clean.

Dont forget to clean and re adjust the sub speed pots on the board, and while you are at it, adjust them so you get the right speed with the main pots at center position. Also remove the 3 connectors and clean the pins with a toothbrush with deoxit sprayed on the toothbrush.

A word of caution: do not spray de oxit on the board, one drop makes the job. If deoxit gets under the black plastic that holds the pins of the connectors, it could melt the glue they use to hold the plastic in place before soldering. This glue gets conductive once melted and could cause various problems like jerky or runaway speed. I know,i have experienced both....

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