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Technics SL1300 speed

Posted: 11 Jul 2019 01:19
by opus007
When i play a 33 LP the speed I have set stays where it is supposed to. When I play a 45 LP I can not get the pitch to stay where I set it. It will stay for 10 to 30 seconds then starts moving out of adjustment. I took the TT apart and cleaned the pots and speed selectors and oiled the shaft.
What should I check next.
Any help appreciated.
Thanks.

Re: Technics SL1300 speed

Posted: 11 Jul 2019 12:40
by KentT
Clean the 33 1/3-45 RPM switch. Their contacts get dirty too. Exercise 20 times. Use a good quality contact cleaner.,

Re: Technics SL1300 speed

Posted: 11 Jul 2019 15:12
by opus007
I have cleaned both rpm switches twice now and given them both a workout and cleaned them several times each time I opened the turntable with deoxit. Still problem persists but only with the 45 RPM as I can not get the strobo steady. Still starts to drift after 10-30 seconds. It starts to loose speed and then really slows down to probably around 33 1/3.
The 33 1/3 switch has no problem and speed stays steady and strobo does not drift.
Not sure what to do next except take it in for service. I called a shop and told them my problem and the tech told me I needed to put it on a scope which I don’t have and to check power which is starting to get outside of my skills. Told him only happens on 45 LPs and I only have one 45 LP. His response was don’t play 45s and just play 33s. Anyway any more thoughts or ideas or recommendations are all appreciated.
Thanks..

Re: Technics SL1300 speed

Posted: 11 Jul 2019 16:01
by georgesgiralt
Hello
Is your SL-1300 a MK1 or one MK2 ?
If it is an "original", the speed is set using the pitch control to set a given voltage to the regulator.
So if the speed is accurate and stable using 33 RPM, and not using 45 RPM, you have to check the wiring around the pitch control, switches and solder to the board. The switch is used to replace a resistance set by the pitch control by another one of different value. It is not rocket science. The schematics is in the library. And give the voltages to check at various points on the printed circuit board.
Keep in mind that you need to have the platter in place BEFORE turning the power on. So it may be difficult to measure the voltages underneath the turntable .....

Re: Technics SL1300 speed

Posted: 11 Jul 2019 16:22
by opus007
The turntable only has SL1300 on it. Can not find any other tags to tell me if MK 1 or 2. I assume MK stands for make. Was told when I bought it a couple months ago that it is original. Will look at the schematics and see how I can check them with the platter on. Any ideas on the best way to do that.
Thanks.

Re: Technics SL1300 speed

Posted: 11 Jul 2019 19:57
by georgesgiralt
Well,
I thought I would have to do it because my old SL-150 was acting a bit funny.
I was fortunate enough that putting new electrolytic caps in it solved the issue.
My thought was to solder insulated wires at the point to measure and letting them extend outside the turntable.
Mark them with a paper and scotch tape and take notes.
But I did not try it...

Re: Technics SL1300 speed

Posted: 12 Jul 2019 01:41
by chiwahua
Have you cleaned ALL potentiometers? (See attached)

There are two obvious with knobs outside and two under the platter. Refer to service manual

Re: Technics SL1300 speed

Posted: 12 Jul 2019 02:30
by chiwahua
And of course you should the 33/45 speed selector SWITCH like KentT suggested

Re: Technics SL1300 speed

Posted: 20 Jul 2019 04:37
by opus007
Yes I took the back off the TT and removed the circuit board to access those two pots and sprayed them with Deoxit. So sprayed all 4. Did this twice meaning on separate days. Watched a video online on how to do it. Also sprayed the 33/45 switch. Really hasn’t made any difference. The 33 speed is steady and when set hasn’t moved a hair out of adjustment. It is only the 45 speed that just will not stay adjusted. It starts to drift as soon as I adjust it. Starts slowly to drift then really slows down. From just looking at it looks like it is slowing to the 33 speed if that is possible.
Chiwahua your third diagram I am not sure what it is I am looking at. Is that where I should measure voltage or something.
Thanks.

Re: Technics SL1300 speed

Posted: 20 Jul 2019 10:51
by chiwahua
The schematic is only to show you that there were 4 pots total.

Well, I don't know what you should do next.. Most of the times, just cleaning the potentiometers and the speed selector switch is enough to get a steady speed. This case requires the input of more experienced users than me...

I'm sorry I can't help you more. Let's hope someone else will have other ideas on this.. There's a lot of very skilled people in here.

Re: Technics SL1300 speed

Posted: 20 Jul 2019 11:07
by georgesgiralt
Hello,
From here, you have to divide and conquer. Look at the schematic above.
I would unsolder the wires at C and D and switch them.
This way, you will use the 33 pot to set the 45 speed and vice versa .
If the problem is still on the 45 speed, the problem in on the printed circuit board. If not, the problem lies in the pot and/or it's wiring.
Could you try this and report back ?
Have a nice day

Re: Technics SL1300 speed

Posted: 20 Jul 2019 20:56
by opus007
Is this where I swap the wires? See Fig 1.

Also in Fig 2 there is what I assume is glue that may or may not have leaked into that pot which is the 45 pot.I tried to remove the pots bracket by removing the screw in the middle but the glue is pretty strong.Did not want to break anything so stopped.I also notice that the 45 pot turns with less force than the 33 pot.

I will have to get a new solder iron to do the wire swap as mine is a high power solder gun and do not want to fry anything as the wires are pretty thin.
While I had it apart again I used the deoxit it on all pots again.
Thanks for all the help.

Re: Technics SL1300 speed

Posted: 21 Jul 2019 10:52
by georgesgiralt
No, I would prefer, as it is easier, to swap the wires at the connector which is in the upper right corner of your first picture.
And no, I do not think the glue is the problem. As glues are often non conductive, if there was a contamination, you will loose the contact entirely and can't set the speed at all.

Re: Technics SL1300 speed

Posted: 21 Jul 2019 16:47
by opus007
So just swap the yellow and orange wires and then use the 33 for the 45.
Thanks.

Re: Technics SL1300 speed

Posted: 21 Jul 2019 21:36
by opus007
I swaped the two wires .Setup the pitch for 45LP. Had to adjust the pot and also speed control under the platter. 45 played with no problems and pitch speed did not drift. Heres a short video:
https://www.dropbox.com/s/vczsarr6xst50 ... 2.m4v?dl=0

Setup the pitch for 33LP and also had to adjust speed under platter.Pitch speed drifted slightly after 2-5 minuets. Heres short video. Its hard to tell but the pitch is drifting slightly:
https://www.dropbox.com/s/zzvrupddl88ii ... 4.m4v?dl=0


After 15-20 minuets the pitch was drifting a lot more. See video:
https://www.dropbox.com/s/cd31rr721wnoi ... .MOV?dl=0]

Before I swapped the wires the pitch was a loosing and gaining speed a lot faster.Maybe due to the 45 spins faster.But bottom line is the speed issue has now transfered over to the 33 speed even though it is not as dramatic. So I am guessing the 45 pot has a problem.

I found these pots (first picture)with bracket and are out of another SL1300(click on picture for bigger view).Mine are the same except the numbers under the 600 (second picture)Will these work?


So should I order these or any ideas on where to go from here.
Thanks.