Hum on Technics SL-23 Turntable


I recently purchased a used Technics SL-23 Turntable. Before I bought it, I calibrated the cartridge and tonearm, and it played vinyl fine. However, when I hooked it up at home to a Marantz 2230, I experienced a background hum simalar to a loose interconnect when the turntable played. It still plays records, but the noise is quite irritating. Any troubleshooting would be much appreciated.

Hi Andy . I don't known yours hum ,but I use same SL-23. How to you calibrated the catridge and tone arm pls suggest me. and this model has phono builtin.

Check the ground wire. Don't forget to ground your turntables!

I also have this TT and only get the hum when I DO connect the ground. What does that mean?

Try these;

One of the power cords in your system is plugged in backwards - you know the large lug in the large hole and the small lug in the small whole. If you have a piece of equipment that has two lugs the same size, drag you fingernail aginst the power cord wires. The one with the ridges is the large lug.

If you have the receiver (or TV) connected to a roof antenna or especially cable TV disconnect the coax. If the hum disapears get a ground isolation adapter from Radio Shack.

I have also heard of some people cutting away a small portion of the shielding of the patch cables to reduce the number of grounds. The cable will still be shielded but will only be grounded at one end.

Hope this helps...

Ship Shipley
Anyone know where to obtain a new drive belt for the SL-23?

where do you put the belt exactly??

Campbell McGuiness
Hmm, are you joking 'Anonymous'? It's fairly easy to figure it out:
- Unplug the thing
- Pull the 'bit which the records spins on' off (it's called a palate I think - anyone?)
- Look under palate & find the circular bit where the belt goes.
- Carefully wrap the belt around this.
- Place palate back on turntable.
- The palate has holes in it. Now slowly turn the palalate till you can see the driveshaft through one of the holes.
- Carefully stretch the belt over this shaft. Use something that won't damage the belt.
- Spin manauly to test.
- Turn the thing on... TADA.

Now that I've contributed my bit. Can anyone tell me where I can buy a stylus and 'end of the tone-arm bit' for an SL-23?


Campbell, have you tried specialist shops for DJ's? I'm pretty sure those kind of shops over here in Belgium still have these items. I don't know where you are located, but I'm always willing to shop around for you and send it. You could pay me through paypal for instance.

Now, here's my problem : I recently brought my old SL-23 down from the attic to digitalise some vinyl records. It hadn't been used for many years and now it turns at irregular speed. I'm not sure it's only a belt problem (I can get a replacement belt custom made by a friend). I suspect there might be something wrong with the servo motor control electronics. Should anyone have the schematics of these electronics, I would appreciate it very much if he/she could mail me a copy. Thanks in advance.

I got my old SL-23 out to start going through my LP collection and found that it is doing the same thing. I can add though, that it is not the belt, as I have just replaced it ($10 Model FM 22.4 at I think you are right about the servo motor control being the problem. I still have my owner's manual, but there is no schematic, just a flow chart showing a few boxes for the control logic. Have you gotten any further in tracking the problem down?

Hey everyone,

I recently took in a stray SL-23 and I'm glad to have it, but since day one it had a problem with keeping a steady speed. I cleaned the switches and the pots, to no avail. Finally, I replaced all the electrolytic caps in the thing. Most of them are all located on one pc board screwed in beneath the platter, except for one in the power supply.

Luckily, these caps all have their values clearly printed on them, so you don't even need a schematic. It was very satisfying to get such results, so I suggest this.

And lubricate the drive motor? With?


Hi Anonymous,

That's a very interesting tip! Caps do tend to degrade in time and it's more than likely that some of these caps are used in the speed control timing circuits and therefore cause instable speed. I'll look into it.
Regarding motor lubrication, I haven't got a clue. Has anybody else a valid suggestion ?

Hi there ,Im in country NSW Australia ,and been using a SL-23 since 1975, lately I been having trouble maintaining a steady speed at 50 HZ on 33rpm I suspect belt as its getting on a bit, who would keep these belts in Australia, Dick Smith only keep a bag of asst, turntable belts, and I have no ides how big this belt orignaly was.
p.s.I have cleaned palate, cleaned and lubricated plate centre shaft,cleaned belt spindle and all belt metal drive surfaces,lubed drive motor shaft am at a wits end ??
need help

i have a SL 23 just bought it at a yard sale and the belt is not on it seems to long for the player can u tell me how to hook it back on very decriptive thanks

Phil Frehsour
I also own a Technics SL-23 with a speed problem. I have replaced the belt and the electrolytic capacitors to no avail. Any suggestions on repair or replacement of the drive motor would be appreciated. Someone mentioned lubrication, would normal machine oil be appropiate? Perhaps the brushes are dirty -- would an electronic contact cleaner be worth a try? Might it damage the motor? Thanks.

To people having speed problems on an SL-23:

I recently bought one in a flea market. The belt had rotten away and left residues on the motor shaft I didn't notice at first. After I installed a new belt (bought locally, Addison Electronics in Montreal, Canada), I could see a recurrent speed variation. Once I cleaned the shaft, this was cured. But I had another speed problem caused by the 33-45 rpm speed selection switch. When moved a little bit around the 33 rpm position, the table would stop or change speed. I cleaned the switch and the two speed adjusment potentiometers from the inside using "tuner, switch and control cleaner" spray (electronic contact cleaner). Then everything was fine. Note to Phil Frehsour: the spray I used contains a lot of solvent and very little lubricant and is flamable, so this makes it a bad lubrication solution for the motor, as it would wash away the existing oil. Looks like the motor is using standard phosphor-bronze bearings, so a very light oil meant for them should work. Stores selling stuff to radio-controlled race car buffs might have someting of that kind.

Charles Bates
Hi guys i recently purchased a Sl-23 from a thrift store. It looked great and was real cheap. I am having some trouble with it and wondered if you could help because I grew up without turntables and don't know much of anything about them. My table has an awful amount of pop noises coming through on a nearly brand new record. Could the stylus be bad? I have the speed problem too but i'm sure its caused by the nasty belt on it. What is the right way to ground the T.T.? Thanks alot

To anonymous (May 16, 2003 message)
Where did you buy those caps at?


Fred Zarecki


Get a good belt from here:

Also, for those of you looking for a new stylus, check this web site:

Finally, the best site for all kinds of parts is this web site:

I hope these help those with turntable problems.

check us out at
we restore turntables and sell needles....
stereo exchange chicago

John A.
Nice site, David. Good luck to Turntable Repair.

Maybe some people don't even know turntables and LPs are still being made, and there is a growing market. There has been no major change in turntable design, so new ones are not better than old ones, they are just new. And an expertly-restored turntable is as good as a new one, and probably a better buy. Also, the neurotic hype and planned obsolescence that insisted on direct-drive, stroboscopes on platters, and all that, is not part of the scene any more. Good thing. I think those guys have infiltrated home theater, instead.

New LPs can be bought from big specialist shops; Virg*n and HMV Shop on Oxford Street, London, have great selections, I saw a while ago, and I expect it is the same in the US. If you live in the sticks, you'll probably need mail order.

I have a Rega Planar 3 from 1979 and its has run without fault. I greased the main bearing about 10 years ago. I listen to CDs too. Some are almost LP-quality.

Unfortunately the big LP makers had major quality-control issues toward the end of their era (warps; scratches; holes not in the middle; vinyl too thin). Their complacency must have helped the CD take off. When they started selling digitially recorded LPs, they as good as gave in.

After reading another thread here, I wrote some things about scratches, static, dust, thumps, rumble, wow and flutter, and how to look after LPs, if anyone does not know, and is interested. This was common knowledge before the age of the CD. It would make a long post. But it is twenty years now since the CD took over, so there are probably a lot of folk who never learned the basics, and the culture of expert dealers is almost gone. I asked a dealer recently if an HT receiver phono input was for moving coil or moving magnet. He had no idea what I was talking about...

I have a Technics SL-23 turntable that I purchased new when they came out. I recently bought and installed a new belt for it. This belt is quite a bit smaller than the belt I took off, but it is the one recommended by When I adjust the speed now, if it is not right on, the turntable stops. Also, I can't play 45's because when I switch from 33 to 45, there is no change in speed. I can email about the belt, but does anyone have insight on how to get my 45 speed back? Thanks.


Usually, with a belt drive turntable there is a pulley that moves the belt up or down to a larger spindle when you shift to 45 rpm. do you see a larger spindle above or below the one for 33 rpm?

Dave Clemens
Unregistered guest
I believe I have solved the speed problem for my Technics SL-20, purchased in 1977. After a belt change several years ago, it worked well until this year (2003) when the speed became erratic, and the 45 RPM setting was no faster than 33 RPM. The problem appears to be in the speed adjustment trim pots. They are nominally 20K and set up as a simple variable resistor, but when I removed one it measured over 25k, and I could not get the "zero" ohms end to be less than 5K. This is because these cheap trimpots have severely oxidized over the last 25 years! They were barely even making contact. This problem seemed to become even more worsened with the tight new belt because of the extra friction. Not wanting to wait for a distributor delivery, I obtained two 10K trim pots from Radio Shack. However, with this modified spec value one must also modify two other resistors to compensate. The 33 RPM speed originally uses a 43K resistor in series with a 20K trim pot variable resistor set nominally to 10K at it's center, creating a total nominal resistance of 53K. When the original 20K trimpot is replaced with a 10K one, the 43K resistor should be replaced with a 47K resistor. For 45 RPM, an original resistor of 30K is used in series with a 20K trim, resulting in a nominal total of 40K. With a 10K trim, the 30K resistor needs to be changed to 35K (33K + 2.2K is fine). The result is actually twice the resolution of speed adjustment. I have not a had a problem since, and 45 RPM is back. Be careful when de-soldering and re-soldering - the circuit board is not that hearty and the tracings break easily; I had to mend a few of them with jumper wire. I imagine the speed control circuitry is probably identical for the SL-23. I hope this helps!

Unregistered guest
I bought an old SL-23 and I had the same speed variation issues. First I thought it was the belt causing this, so I changed it. This didn't correct the problem. Then after reading the messages here, I decided to give it a shot to plug it into a UPS instead of directly to wall socket. Voila! It worked: the speed is completely stable. The UPS (I used APC Back UPS ES) not only provides uninterruptible power but also provides pure 60Hz AC, I guess this corrected the issue.

Unregistered guest
I have a another SL-23 with the irregular speed problem. I have noticed that when I adjust the "speed adjust" the speed goes crazy. I think the Dave Clemens resolution is probably the apt solution, but I am wary of the fact that he has an SL-20. I would like schematics for the SL-23 so that I know the right resistors or trim pots to buy for my SL-23. If anyone can help me, I am a little uneducated in electronics, could you make it very simple for me.

Unregistered guest
I replaced the 5k trim pots in my SL-23 to a little bit of success (my 33 rpm is working much better but my 45 rpm is still not working.). I was wondering if anyone can help me with the speed variation since the trim pot replacement did not solve the problem.

Yeah, Ryan ... JUNK IT !!!

Unregistered guest
Glad I found this site, hope there is some help out there. I have a SL-BD20D. It's only about a year old but from day one I've had the problem of the needle dragging across the record when the tone arm is returning. I've tried the adjustment mechanism but if I get it to not drag on the return there isn't enough pressure to keep it from constantly skipping when I play the record.

Unregistered guest
I have a Technics SL-20 (F-G-Servo Player) for more than 20 years and the speeds are presently giving problem ... one is playing and the other is not. I am searching for an Integrated Circuit Part # C1003. I live in Trinidad (one of the islands of the Caribbean) and is looking for the closest place I can purchase this part. The serial number on the product is SFNN02021C01.

Unregistered guest
yeah, i just recently came across an sl-23, handed down to me from my uncle, and it won't even begin to spin. i can hear it trying to but it won't budge. any tips?

Kirsty Malcolm
Unregistered guest
I've just dusted down my SL 23 and found it barely moves. Being a girl I've no idea if it's the belt or any of the other causes listed so brilliantly by all you other SL 23 fanciers - but I'd really appreciate help finding someone willing to repair the thing,in London (UK) and ideally in West London, near Portobello.Reward offered.

Unregistered guest
My SL-20 has a burned-out power transformer. I don't have a schematic diagram and have not been able to locate a replacement by it's number. Does anyone know the secondary output voltage? I think I remember 24 volts, but I'm not sure.

Unregistered guest
Mine spontanoeusly feels like slowing down then speeds up, then goes back to 'normal.' My dad says that the turntable's shot.... how can I fix that?

Unregistered guest
I have an SL-23 that I picked up at a garage sale. When I place the needle on the record the power light is on but the platter doesn't turn. I've seen several other requests for manuals but don't know if any of these people received one. I'd be grateful for some advice.

Greg B
Unregistered guest
My SL-23 (purchased new in 1977) has been sitting boxed and ignored for several years. I got the urge to hook it up and listen to some vinyl today, instead of the "sterile" CD sound! I immediately noticed that it needs a new belt. After cleaning and oiling the motor, it has started turning ... but the motor seems to only run intermitantly, and the intermittent problem seems to center around the 45/off/33 switch. Does anyone know what that switch is (values, part number, etc), and where to find a replacement, in case I need to replace it? I am really looking forward to listening to some vinyl again! THANKS!

Unregistered guest
I have this beautiful Technics turntable that I found in my former neighbor's trash. He was a doctor, so I forgive him and am grateful. He set it so that some less fortunate sole would enjoy the find.

Now, at the begining it played fine. There was a humming noise that grounding the table erradicated. The problem is that sometimes it does not produce a sound. I can hear it if I put the volume high but not enough to say it works so that I can enjoy my record collection once again. I was looking for an authorized dealer to have it fixed. Is this a big problem? I am at work, I don't have the model number at hand.
Does anydoby have a clue?
Thanks in advance

New member
Username: Kester

Post Number: 8
Registered: Oct-04
try this site

Brand Model Number Format Price

outa here

Unregistered guest
I am working out the schematics for the SL-23FS and need help with the DIP IC. The only markings on it are "K650 C1003", and I cant find a reference to it anywhere.

I have the CCT boards mapped out and a CCT diagram drawn, just missing the DIP IC info - WHAT IS IT??????

My plan is to build an external power supply with remote mounted controls.

I have 3 if anyone wants spares

Unregistered guest
i have a SL-L25 turntable. the above instructions for putting on the drive belt was not specific enough for me. can anyone help me?

Hi...Guys...I have a Technics SL-Q303 Turntable..The problem is that the power transformer went dead...and i dont know which one to replace with. The original was already replaced when i bought it second hand...can anybody tell me the output voltage of the power transformer for this turntable. The input voltage is 220v.

Unregistered guest
I have a marantz 2230, and have bought new turntable. Problem: I don't see anything to hook the grounding wire to on the backside of it. Anyone advise??


Unregistered guest
Does anyone out there have a weight ( one used to adjust the amount of force put on the cartridge and stylus ) for a technics SL-23 turntable. I bought the turntable off ebay and when I went to set it up to my reciever quickly found it had the wrong weight on it.

Unregistered guest
Looking for power cords for 1) Technics SL-B210 turntable and 2) Technics SL-5 turntable. And, yes, I am 103 years old.

Unregistered guest
sorry to ask this seemingly stupid question but How do I GROUND my SL-B20 Technics Turntable? Thanks in advanced.

Pleas help -I just hooked up my old receiver , technics turntable (SL D205 ) and Bose speakers . The radio plays fine but when I turn the receiver to Phono the hum is really loud . Any suggestions ? Is it the turntable or receiver ?

New member
Username: G6mxl

Post Number: 1
Registered: May-05
There are several postings here about wow on Technics SL23. I found that replacing the 10uF electrolytic capacitor on the servo board made a major improvement. Take care when removing the old one as the leads are bent over on the circuit side of the board. Modern replcements tend to be physically a little smaller. I obtained mine from Maplins in the UK.

Hey, glad I found this site. Looking for an owners manual for Technics SL23. Any ideas? Just picked it up at a garage sale. Thanks, Katt

Candy in Oregon
Unregistered guest
I have a Technics SL 230. I have figured out where to buy a replacement belt, but where can I find a light bulb so I can calibrate the speed?

New member
Username: Budster2

Louisville, KY

Post Number: 1
Registered: Oct-05
Just reactivated my SL-23. Speeds were a little shaky til read some posts here. Use a little silicone spray on a Q-tip and touched the drive shaft just BELOW the drive pully under the turntable. Seemed to even out both speeds. May work for you. Great site.

Unregistered guest
I just Purchased a Technics SL 23 that was Garaged then totally serviced with New belt ,Lubed & Adjusted.It looks better than new .
for $55.00 Are there any things to look out for on these 1975 models that might cause problems. Hell for the Price I shouldnt worry-Damn these things were beautifully built.

Unregistered guest
Just buy a new turntable the sl-23 is cheap 80s model, go to craigslist there a dime a dozen..
hum is either, no ground in your home plug, or not properally grounding to your ground source., chose a seperate ground., get new rca plugs out the back, make sure wires connecting cartridge are not touching tone arm, or eachother...
slower speeds.. motor is going, belt is worn or stretched...
again., to revive those sweet sounds from vinyl... why ruin the whole deal with a dodgy table... just spend a few dollars, or rent one.. for a weekend...

Unregistered guest
I have a Technics SL-5. It seems that records are skipping in places they should not be skipping; i.e. no scratches or dust, etc. Is that a stylus problem or something? Also, if I am in need of parts, where is a good place to get them? I need a preamp. Any suggestions?

Unregistered guest
I got my dads old SL-23 and I am having problems with noise. It is too quite. It still sounds alright when turned all of the way up. Do I just need to replace the stylus or rewire the audio outs. I can do basic wiring and would be willing to undertake a project, so just throw stuff at me. Is doing all that even worth it for this turntable or would I be better off getting a new one.

Unregistered guest
I was given a Technics SL 23. I need to replace the cartridge as no replacement stylus is available. I need to know the spacing measurement for the new cartridge when I install it. Also what are these caps etc. I'm reading about. My table is fine for speed, then slows for a second or two, then is ok again. Thanks for any or all help,

Rich Berges

Unregistered guest
Hi! I'm looking for a replacement power cord for my Technics SL-L3. Anyone know where I can get one? Thanks for your help!

New member
Username: Uncle_ants


Post Number: 7
Registered: Jan-06

It might sound like a daft question, but when you say too quiet, do you mean very, very quiet indeed? Have you just plugged it into your amp? Is it plugged into the input marked phono?

New member
Username: Pwbs24

Post Number: 1
Registered: Apr-06
I live in Australia and bought a technics 1200 with and American power cord. I bought an adapter an plugged it in. Before i connected the av cables and ground i turned on the power, the light turned on for a moment and then went out, there was also a click noise when it went out. It now won't turn on at all?? Have i broken something?

New member
Username: Johnpaul

St. Louis, MO USA

Post Number: 3
Registered: Oct-05
I had the same problem with a hum on my Technics SLBD35 and I am happy to report that the Ground loop isolator from Radio Shack has fixed the problem.

thanks guys isolation&kw=ground+isolation&parentPage=search

New member
Username: Gaje

Sydney , NSW Australia

Post Number: 1
Registered: Apr-06
Lee check the input voltage range, does it cover 110v - 240v...or only 110-120v.
if the latter have cooked it.

New member
Username: Pinkpantha4200

Post Number: 1
Registered: Nov-06
I found my old Technics SL-23 that has been stored in the attic for the past 4 years. It used to play and now it doesn't. It is getting power, lights up when the arm is above the record, but it doesn't spin. Any thoughts on what I could do to restore it?

New member
Username: Wang

Merthyr tydfil, Wales Wales

Post Number: 1
Registered: Dec-06
i own a pair of numark tt1625's but when i am playing them after about 20 mins they start to slow down then come to a complete stop but when i switch them off for 5 theyre ok for a bit then it happens again, what could be wrong

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