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Thorens TD-125 Turntable Repair & Restoration

I was visiting a friend recently, chatting to his father, Neil, who is very ill. I saw that his cherished Thorens TD-125 Mark 2 was languishing, non-functional, in a pile of dust and dirt.

The Thorens clearly hadn’t been operational in a long time and when Neil expressed disappointment that he wasn’t able to play his records any more, I decided to completely repair and restore it for him, hopefully finding the fault that had put it in the corner in the first place.

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Deck as I received it, minus platter and lid, ready to commence cleaning
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Heavily corroded platter – I was not particularly going to go crazy here as it is a cosmetic issue only
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Filthy arm and arm board
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Filthy everywhere else too of course

I have a basic plan I stick to with restorations like this one. It involves first stripping the deck of all large parts and setting them aside for cleaning. In this case I removed the lid, platter and mat.

I then use a special foaming cleaner to remove dirt, dust, cigarette residue and grease from every component. This is a slow process but yields great results. I also usually wash rubber mats in a mild detergent solution in warm water.

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Ambersil foaming cleaner really is great stuff
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Look at the muck I’ve removed here

With all this done, I cleaned away the residue from the old and perished rubber belt. The old belt had broken down, leaving bits stuck to the pulley and hub that the platter sits upon. I also carefully cleaned the tonearm and re-tensioned all the screws and fasteners I could easily gain access to.

Next up was to diagnose why the deck didn’t work. I checked the power supply and found that I had rails, but two larger electrolytic capacitors in the motor drive circuit had died and this meant that the motor would not run. I replaced these and sure enough, the motor now turned.

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With the bottom removed, one can gain access to the motor drive circuit
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The two ROE axial electrolytic capacitors under the bracket on the left were dead. Note the array of speed and phase adjustment trimmer potentiometers. The Germans know how to do this stuff properly.
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I removed and replaced them with nice NOS Philips parts

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Next step was to clean and re-lubricate the spindle bearing and any other mechanical bits that needed it. On a deck of this age, it’s likely that the spindle won’t have been re-lubed EVER and this was apparent when I removed the hub from the deck. The bearing was completely dry, so I cleaned the bearing and bearing well and added the correct amount of my special synthetic turntable bearing oil.

Next I rigged the deck up with a new belt, replaced the platter and started the function testing and adjustment of rotational speeds. Motor phasing adjustment is critical in these decks. It sets the correct drive speeds and more importantly, minimises noise and vibration from the motor. This step is critically important or the motor won’t run smoothly.

Luckily the service manual explains the process fairly clearly, but you need an accurate DMM and some previous experience in working with electronics or you could really cause some problems by attempting this. I soldered some wires to the test points in order to maintain a good connection with them whilst juggling the deck, a screwdriver and watching the DMM.

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Performing the motor drive phase adjustments is critical on a Thorens TD belt drive deck

Almost done, I restored the strobe assembly, which was cloudy and not correctly aligned. To do this, I stripped the assembly and cleaned each component, before reassembling the parts and checking their alignment. Alignment is set with the platter and mat attached, as loading the suspension changes the alignment. Patience is needed here.

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Strobe assembly after cleaning and alignment

The final jobs were to carefully clean the stylus assembly of the original Shure V15 Mark 3 and align the cartridge correctly in the gorgeous SME Series 3 tonearm. I adjusted all aspects of the tonearm, which was not well setup for the cartridge it was carrying. This was likely the result of my buddy and I partying too much all those years ago when we used to use Neil’s equipment in the basement of their old house.

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Very cool Shure V15 cartridge with high-spec hyper-elliptical stylus assembly. This was one smooth-sounding deck when finished..

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Anyway, the Thorens TD-125  performed absolutely beautifully once restored and now looks a million bucks. Neil told me just how thrilled he was with the result and he can now enjoy all his records once again.

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What a difference!

5 thoughts on “Thorens TD-125 Turntable Repair & Restoration”

  1. Lovely Thorens TD-125 you have restored.. I have done up a Thorens TD-160 which was rather stuffed. Now looks a treat . Nice turntables.

  2. Hi there
    Have a Thorens TD 318 in almost perfect condition, except for the lid
    Does anyone know if the hinges can be removed at all, looks like they are welded on the bottom plate

    Cheers

    Manfred

    1. Hi – I haven’t worked on this deck, but if it was put together, it can be taken apart. The hinges themselves may be a welded part, but they should be removable. I would need to see the deck to be certain though.

  3. sounds like you know what you’re doing. I have a TD125 and the platform has sagged so that the platter drags on the platform. I’m thinking of disassembling it and heating it at a low temp to see if would return to its original shape. I would appreciate any advice you could give me because I hate the idea of disposing of it.Thanks in advance for any help you can lend.

    1. Hi Thomas, I presume you are referring to the springs? You could try this, though this may affect the tempering of the springs. Another option would be to shim the springs, therefore adding the needed preload to them. You could also source new springs.

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