Sl-7 Disassembly Problem

turning japanese
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xspiritdannyx
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Re: Sl-7 Disassembly Problem

Post by xspiritdannyx » 25 Nov 2015 05:56

Hi everyone,
I just bought a used but great condition SL-7 off of craigslist for $50. Everything seems to be in working order but the seller does not know if the belt was ever replaced or if it has ever been serviced.
I'm not familiar with how linear tracking tables work but when I put my ear against the turntable while its playing, I can hear a very slight motor noise every time the arm adjusts to the left. It occurs around every 2 seconds and the position indicator jumps a quarter of a tick on the indicator but sometimes jumps around 75% of a tick. I've seen people describe "buttery smooth" and I'm not sure if my turntable fits that definition.
I guess I'm just not sure what to expect from this beast. This is my second turntable, my first one was a Sony LX 250H which somehow managed to disappear from my house :cry:

fscl
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Re: Sl-7 Disassembly Problem

Post by fscl » 25 Nov 2015 17:25

xspiritdannyx wrote:Hi everyone,
I just bought a used but great condition SL-7 off of craigslist for $50. Everything seems to be in working order but the seller does not know if the belt was ever replaced or if it has ever been serviced.
I'm not familiar with how linear tracking tables work but when I put my ear against the turntable while its playing, I can hear a very slight motor noise every time the arm adjusts to the left. It occurs around every 2 seconds and the position indicator jumps a quarter of a tick on the indicator but sometimes jumps around 75% of a tick. I've seen people describe "buttery smooth" and I'm not sure if my turntable fits that definition.
I guess I'm just not sure what to expect from this beast. This is my second turntable, my first one was a Sony LX 250H which somehow managed to disappear from my house :cry:
Check out this utoob showing the drive mechanism and what / how tonearm travel should work to track across the vinyl. This video is also on Page 10 of this topic:



Skip to 26 minutes into this video and it will show the motor driving the worm gear resulting in "buttery smooth" tracking....... =D> =D>

If this is not happening then the opto sensing system may need to be adjusted. This can be found on page 9 of this topic. Here's the direct link:

https://www.vinylengine.com/turntable_f ... 28#p527228

Oil the tonearm drive motor shaft and run the motor in both directions using a 9V battery.

Watch the entire video for more tips.

Hopefully, this will restore proper function of the SL-7 like the utoob above ^...... [-o< =D> =D>

Good luck and welcome to VE.... :)

Fred

xspiritdannyx
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Re: Sl-7 Disassembly Problem

Post by xspiritdannyx » 25 Nov 2015 19:55

Hi Fred,
Thanks so much for the detailed reply and the warm welcome to VE. Judging from the video, the tonearm also seems to move to the left every two seconds so I think that's the norm. I've never actually opened up a turntable before, but I open up computers and laptops on a regular basis so I'm hoping some of that experience transfers over. Do you recommend any specific kinds of oils when doing this? There's a Liquid Bearing Oil on Amazon that seems like it's specifically for turntables so would this do the job? http://www.amazon.com/Liquid-Bearings-1 ... ntable+oil
Also, I'm not familiar with cartridges and styluses for the SL-7 whatsoever. It has an Ortofon cartridge and I'm not sure what kind of stylus it has. I'm not running the turntable through anything super fancy, just a 2.1 Klipsch computer speaker system through a phono preamp. So are there any good budget cartridge and stylus combos you recommend?\
Many thanks, and happy thanksgiving to all.

fscl
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Re: Sl-7 Disassembly Problem

Post by fscl » 28 Nov 2015 03:04

xspiritdannyx wrote:Hi Fred,
Thanks so much for the detailed reply and the warm welcome to VE. Judging from the video, the tonearm also seems to move to the left every two seconds so I think that's the norm. I've never actually opened up a turntable before, but I open up computers and laptops on a regular basis so I'm hoping some of that experience transfers over. Do you recommend any specific kinds of oils when doing this? There's a Liquid Bearing Oil on Amazon that seems like it's specifically for turntables so would this do the job? http://www.amazon.com/Liquid-Bearings-1 ... ntable+oil
Also, I'm not familiar with cartridges and styluses for the SL-7 whatsoever. It has an Ortofon cartridge and I'm not sure what kind of stylus it has. I'm not running the turntable through anything super fancy, just a 2.1 Klipsch computer speaker system through a phono preamp. So are there any good budget cartridge and stylus combos you recommend?\
Many thanks, and happy thanksgiving to all.
If it is all working and sounding fine, then I apply the old adage "if it ain't broke......" and continue to play LPs on the SL-7. It wouldn't hurt to oil the center spindle, however, it takes a bit to remove the platter and get to the location where the oil needs to go, IIRC.

The SL-7s in the US, IIANM, were fitted with Ortofon TM-14s. That's what came on my SL-7. If there's no distortion during playback, it should be OK. If not search "Ortofon TM 14 Stylus Replacement" and you'll find available styli as replacement or even upgrade. Can't remember the seller, however, just bought a generic TM-14 replacement which sounds very good in the 7.

Good luck.

Fred

xspiritdannyx
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Re: Sl-7 Disassembly Problem

Post by xspiritdannyx » 30 Nov 2015 02:52

I decided not to risk ruining any of my records with a worn stylus and just ended up ordering an Audio Technica AT92E from Amazon for $20. It fit perfectly into the SL-7 and sounds great! A bit bassier then the stock Ortofon cartridge and stylus and the mids have a little less clarity but I'm not complaining for $20. The table runs like a champ so I've decided to just let it be and play records. Thanks for the advice!

fscl
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Re: Sl-7 Disassembly Problem

Post by fscl » 26 Jun 2016 18:28

From an SL-5 Topic:

viewtopic.php?f=18&t=88054&p=731721#p731721

Thanks to BigStu =D> =D> =D> :
big_stu wrote:There are quite a few closed topics relating to issues with the Technics SL-5 tonearm movement - most of the solutions involve replacing the drive belt and/or cleaning & lubricating various parts of the tonearm drive train. Although these had a beneficial effect for me I wasn't completely satisfied the problem was truly fixed. The arm travel was not as smooth as I thought it could be. So...

I looked carefully at the schematic in the service manual. At the heart of the tonearm motor control are two pairs of transistors Q401,Q402 and Q403,Q404.

I removed both pairs of transistors from the main circuit board and put them on my tester. Whilst Q401 & Q402 were slightly below spec I found that the gain (hfe) on both Q403 & Q404 was significantly below the values stated on the datasheet (a long way below). The
part numbers are specced on the schematic as 2SD638 but a pair of 2SD639 were fitted to my board. I found a couple of new replacements for a fiver on the bay and soldered them in. The tonearm now moves smoothly with complete authority - an amazing improvement!

Anyway I hope that some of you find this usefull
Fred

fscl
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Re: Sl-7 Disassembly Problem

Post by fscl » 04 Sep 2016 06:23

Intermittent tonearm wire failure solution, thanks to Petervv:

viewtopic.php?f=16&t=85778

Fred

Wirehead
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Re: Sl-7 Disassembly Problem

Post by Wirehead » 30 Oct 2016 06:46

Can anyone confirm the adjustment procedure (step3 in the service manual - tonearm adjustment) - It seems impossible to get the required 15V (especially because the device operates on 12V..) on full swing. Seems more like it should be 1.5V

fscl
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Re: Sl-7 Disassembly Problem

Post by fscl » 31 Oct 2016 02:40

Wirehead wrote:Can anyone confirm the adjustment procedure (step3 in the service manual - tonearm adjustment) - It seems impossible to get the required 15V (especially because the device operates on 12V..) on full swing. Seems more like it should be 1.5V

On one of these pages is an easier procedure to adjust tonearm as opposed to using 1mm calibrated test vinyl, etc..... :?

Sometimes, I believe, manuals were purposely misleading to protect manufacturer's "secrets" during the highly competitive "sound wars".

Will comb through if you can't find it.

Fred

Wirehead
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Re: Sl-7 Disassembly Problem

Post by Wirehead » 01 Nov 2016 15:07

Yes, I already saw that reply.I had already made adjustments so that it moves in a smooth motion, barely visible by the eye. Which seems correct to me. Sounds perfect as well.

However, it seems odd they would be so far off on that measurement. I know those opto-sensors go bad in time - but 15V vs. 1.5 V seems odd. (Had the same with a Pioneer PL-L50; upon replacing - a world of difference)

dutchflea
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Re: Sl-7 Disassembly Problem

Post by dutchflea » 01 Nov 2016 17:40

15V is wrong indeed, it should be somwhere in the 1.5 to 1.6 V region. The range will be from around 0V to + or - 1.6V when moving the arm from the left to the right. The absolute voltage does not matter too much, what is important is that the voltage is exactly in the middle of the range when the arm is dead center.

So make sure that the arm is perfectly parallel to the record groove before you do any of the electrical adjustments by adjusting the mechanical screw below the arm, where the arm lift is (offset angle adjustment). Only then adjust the hex side screw to get the center voltage right in the middle of the range.

Next follow the gain adjustments explained in the service manual. For the final offset adjustment of course you do not have the official 1mm pitch test record. Luckily this is not needed: I recommend using a 45 rpm 12 inch record with only one song, which will get you close. Adjust the offset in such a way that the arm is centered on average, i.e. the small (trailing) angle at which it starts to move to correct the position is equal to the small (leading) angle to the other side just after it made that correction.

Good luck!

Wirehead
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Re: Sl-7 Disassembly Problem

Post by Wirehead » 02 Nov 2016 12:41

Actually, the 1mm pitch record could be done.. There are people with manual lathes who can do direct to vinyl transfer (no lacquer). Not the best quality in sound, BUT not needed, it's just the 1mm pitch we are after.

For people in Europe, there are some in Germany / The Netherlands. I'll see where that goes.

To dutchflea: thanks, that's exactly how I did it. It's all relative, however, it would be nice to be able to verify.

Electone
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Re: Sl-7 Disassembly Problem

Post by Electone » 06 Nov 2016 14:00

I was considering one of these. It powered on and the LEDs would illuminate, but the TT would not spin, nor would the arm move when the play button was pressed with a record in place and the lid closed. What could be the issue because if it is relatively simple, I would consider picking it up in an attempt to repair it.

Wirehead
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Re: Sl-7 Disassembly Problem

Post by Wirehead » 07 Nov 2016 05:04

I've seen that issue with an SL-7 that had a bad regulator (12Volt one). Voltage would sag when trying to spin.

shaftmaster
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Re: Sl-7 Disassembly Problem

Post by shaftmaster » 04 Dec 2016 18:16

Just wanted to say thanks for all the information in this thread and on this site. The ability to download service manuals is extremely helpful.

I have an SL-J33 that I bought new a very long time ago which had been sitting in a box for the last 15 years. When I tried using it recently, it did nothing other than light the power LED. I was able to get it working again by cleaning off the old grease and manually rotating the tone arm belt to loosen up the mechanism.

I installed a new tone arm belt (found several suppliers on eBay) and I'm ready to put the dust cover back on. But first I'd like to re-lubricate the parts which I cleaned. Does anyone have a recommendation on what lubricant to use? I've heard that some type of dry teflon lube is preferred. If so, can someone recommend a particular brand?

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