Kenwood KD-500 / KD-550 Turntable Motor Service

I’m sure every regular visitor to my site knows just how much I love the old Kenwood KD synthetic composite turntables, especially the KD-600/650 series. But the classic Kenwood KD-500/550 is far more common and so I’ve written an article about servicing their direct-drive motors, for anyone who can’t get their deck into me for service, or who just wants to do it themselves.

The Kenwood KD-500/550 turntables utilise a powerful brushless, slotless direct drive motor that spins the platter directly – no belts, pulleys or gears are used, hence the term ‘direct-drive’. These motors are so well-built and so over-engineered that they are usually still going strong, 40+ years after the decks were made. This does not mean that they don’t need maintenance however.

My belief is that the engineers who designed these turntables never envisaged that they would still be in use, let alone running so well and be in demand all these years later. As a result, service documentation typically lists the motors as being sealed for life and not requiring any service. The reality is that, after 40+ years of use, these motors definitely DO need service! I’ve written lots about these Kenwood decks elsewhere on my site, so have a read of some of these other articles, like this one, or check the Liquid Audio KD-500 archives!

Motor services like this is are very common jobs for me. In fact, a large proportion of the work I do is on direct-drive decks like this Kenwood KD-500, fitted with a lovely SME-3009, a wonderful combination. For this service, I attended to the whole deck of course, but here we will focus on just the motor itself. After a proper service like this, and the addition of a high quality synthetic bearing oil – like Liquid Audio bearing oil which I will soon be selling on my site – you will have a quieter, smoother sounding deck, with better imaging and more relaxed presentation. It really makes a difference and is well worth doing every 3 – 5 years.

Typically dirty and well-used KD-500 here. All the grime will soon be gone, but lets focus on that big motor, in the middle!
After removing the rubber mat, gently and evenly lift the platter, jerking it upwards to break the seal developed over time. The top plastic cover needs to next be removed. This involves removing a few small screws, just keep them somewhere safe. Once you have the cover off, you will see the rotor, spindle and FG disc which generates the signal monitored by the deck to keep a constant speed. The frequency of the generated signal is directly proportional to the speed of rotation…
Very carefully loosen the post that the FG sensor sits on. Be careful here, this is delicate work, you do not want to break anything at this stage. Once loosened, you can gently move the sensor away from the FG disc and then lift and remove the rotor. Here you can see I have lifted the rotor upwards, past the sensor. Keep going!
This is the view once the rotor is removed, looking down onto the stator and windings that drive the rotor. The bearing well needs to now be very carefully cleaned with a lint-free cotton swab. All traces of old lubricant and residue need to be removed, take your time and use a solvent if necessary.
You can see that this bearing was quite dirty, filled with dried up, oxidised lubricant that was no longer doing its job.
The rotor in all her glory, this also needs to be gently cleaned and should be spotless before reinsertion into the bearing. Take your time and be very gentle with everything, the ferrite magnets are fragile!
After adding just a few drops of synthetic bearing oil, enough to just cover the bottom of the bearing well, you can lower the rotor/spindle assembly back into the motor. You need to make way for the sensor again, and don’t force anything, this may take several hours to settle in a low-tolerance bearing.
This took about an hour to settle to this point. You then need to carefully move the sensor back into position.
You are now almost done – reinstall the plastic cover and reattach the platter. You need to test the deck now. Sometimes, when the sensor is moved as you need to do to service the motor, the speed lock may not work quite right. Don’t panic, you may need to adjust the position of that sensor. This is easily done, just loosen the two screws that hold the base of the sensor post slightly and move the sensor so that, when you look from above, it sits symmetrically and centrally around the slotted FG wheel. Tighten, test again and make any small adjustments that are needed. Enjoy your serviced deck!

29 thoughts on “Kenwood KD-500 / KD-550 Turntable Motor Service”

  1. The platter on my KD550 moves horizontally ever so slightly. I am worried that the spindle is bent? When I look down on the spindle, with the platter removed, I can see the whole spindle assembly moving side to side. Again, very slightly. Is there a fix for this? Should I ven worry about it?

    1. Hi Chris, unfortunately you definitely should worry about this if you can see the spindle wobbling without the platter. The best way to measure this is with a dial gauge, measuring runout. If the spindle is bent, the deck will never play a record properly, though it will still play them. You need to establish where the bend is, if any, and work from there. There will always be a little movement between the platter and spindle, as they are just an interference fit. regards, Mike.

  2. Wonderful site. Nice to find another appreciator of these great Kenwood machines. I started with a KD-2055 and was hooked.
    I just found two KD-5070 models here in Denver, Colorado. I see that you are focused on the non-automatic models. I get it. However, when fixing the return mechanism on one of mine I loved the ballet mecanique taking place underneath. I’m designing a mirror-box mount to show off the workings.

    1. Hi Nik, thank you very much, very kind of you and glad you like the site! Yes these classic Kenwood decks are very lovable. I agree, the mechanisms in some of these decks are something you have to see working to believe!

  3. Excellent website, Mike! Just got my KD-550, and I’m using the stock arm. There is some bearing play when I move the arm so thinking about a new arm. You mentioned SME 3009, but are others possible for reasonable dough? Jelco gets some positive comments, for example. Sort of hoping not to need a new arm board… Appreciate any advice.

    1. Hi Jim, my best advice would be to get the factory arm sorted out. Bearing freeplay can be adjusted with the correct tools and this is a better option than removing the factory arm and replacing it in my opinion. If you do swap out the arm, you’ll most likely need a new arm board, another good reason not to do it!

    1. Hi Mike, as always this comes down to budget and a range of factors like what other gear you are using. Do you want to go moving magnet or moving coil? Can your gear and budget cope with moving coil? We then need to look at compliance and get that matching right. Starting at the bottom though, you could start with the Ortofon 2M Red, and go up from there. This gives you an upgrade pathway, with compliant, moving magnet cartridges that sound good.

  4. Thanks for the info. I’d like the be at the $200 budget. Maybe $400 if the benefits are there. MM. will be using between a Pioneer SA 9500ii and a Sansui 9090db.

  5. Thanks for taking the time to post your work and findings for the kd500. Very good infos you have on your site. Have this problem with my kd500, it spins really fast, like turbo charged fast, regardless 33 or 45 selected or adjusting the pitch controls doesn’t change anything. Could it be the speed control or the led speed sensor thing? Is this problem serviceable? Appreciate your advice. Thanks:)

    1. Hi Adrian, thanks for liking the site and commenting. Yep it sounds like you have a motor control issue. I’d need to have the deck in for a proper inspection to go much further. People often fiddle with the motor and this can damage the very delicately adjusted speed sensing mechanism. But yes, all of this is serviceable, depending on what’s wrong of course. Are you anywhere near Perth..?!

  6. See no comment posted here for quite some time… But appreciate this site very much! I have the KD500 and it works fabulously most of the time. But every 10 hours or so, sometimes more often the rpm slows down for 5 to 10 seconds then returns to normal. Is that a sign that the factory lubricant has deteriorated?

    1. Hi David, thanks for your comment and glad you are enjoying the site. The speed variations you mention are a sign that the deck needs a really good service. Everything will need attention, from the speed control trimmers on the deck and motor, to the lubricant in the motor. This is all quite expected of course in a turntable that is 40 years old! Do you have someone local you can take the deck to for service?

    1. Hi Tobias! No, the 500 is designed for shorter arms, even a 10 inch will be tight and may not fit on that deck, unlike the 600 and 650 which are happy with 10-inch arms. A 12-incher would have to sit somewhere outside the plinth on the 500, so not really an option.

  7. Hi Mike, this is Mike from a small town in Georgia, USA. I have a KD-5070 that I bought new in 1978. The return/set-down mechanism will not adjust. It comes up short when starting a record. I know you like manuals, but I’ve got what I’ve got. I think my kids over adjusted the screw. I cannot see a screw head when I look down the adjustment hole. I cannot find a service center nearby. Is this a fix I might be able to accomplish? I am fairly mechanically adept and willing to try. PS – run perfectly otherwise!

    1. Hi Mike, sorry I missed this comment, my spam filter collected it for no good reason! Yes, you could certainly try this adjustment yourself if you have a suitable tool and some patience. This adjustment is generally considered an end-user type of adjustment on most decks, so why not try. If you have no luck, the next step will be to dig deeper.

  8. Hey there, first off thank you so much for your thoughtful reviews and being willing to share your wealth of experience! I am new to the turntable world and acquired a KD-550 used. Runs well etc.. but I noticed the fishing line that connects to the counterweight is no longer connected. And is it necessary to fix? How do I remedy this?
    Again greatly appreciate all you do for this website!

    1. Hey Chad, my pleasure and glad you are enjoying the site. Your antiskate weight appears to be broken and yes, it needs to be fixed. I fix them here of course but you may be overseas. Get in touch via my contact page if local.

      1. Thank you for the reply, I am located over seas unfortunately. Any tips or resources you know of so I can potentially do it on my own?

        1. No worries Chad, I don’t know of any resources related to this, you need the original anti-skate weight or something equivalent and some very fine nylon monofilament. From there it’s painful but see how you go.

          1. Haha I appreciate your honesty. Thanks again, definitely not going to be spinning any more records until I get it fixed. Look forward to what the future holds for this site.

  9. Thanks so much for sharing your knowledge! I’m working on a KD-500 service… cleaned pots, lubed motor. I’m having some issues with speed stability… does the servo require the platter mass to be present or should speed be ~stable without the platter? Without the platter, I get a large oscillation in speed… with the platter, it is greatly reduced but I can see the strobe position oscillate at a low frequency (~1Hz). The strobe moves position by a few mm, then returns, approximately once per second. I’ve tried moving the opto-sensor but haven’t had any luck.

    1. Hi John, thanks for your comment and my pleasure! Technical enquiries can be made via the form on my Contact page, but briefly yes, the circuit relies on the mass of the platter, which must be installed for smooth operation and integration of the drive pulses. Any rotational unevenness with the platter installed indicates a need for further work.

  10. Hey Mike – do mind letting me know what kind of synthetic bearing lube you used on this and approximately now many drops you put in. Also, do you typically replace the trust plate. Thanks in advance.

    1. Hi Lorne, I can’t provide this sort of technical information here unfortunately, as my competitors regularly visit and comb through what is already a goldmine for them. We have an advisory service though, which you are welcome to utilise, accessible via our contact page.

Thanks for visiting! Comment, like, share, subscribe. Our advisory service is available via the contact page.

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