thorens TD 124 motor switch

[wer]

My 124 has a reed switch which turns on the motor when the rotary speed selector is turned to engage a speed. Unfortunately it no longer makes reliable contact

and cleaning the contacts does not help.
Has anybody ever heard of a replacement switch, i wonder, because I am not even able to find a reference to it.

 

[Tony L]

Are you certain of a problem with the switch? It is a very simple device, but can be fouled by either the switch suppression capacitor or the wiring, both of which can stop it opening/closing correctly. Depending on what the fault is it may be a problem with the capacitor too, e.g. if it has shorted-out the deck won’t turn off. I’d certainly look very carefully at that area and check things with a multimeter.

 

[wer]

Thank you Tony. I had it on the bench, and it is quite easy to observe it's operation. The contacts frequently do not make a proper connection. If I gently push the reed there is a tiny spark and control. Possibly there is a slight misalignment, but I can not see if (severe AMD). The capacitor is almost new.

 

[Tony L]

Carefully check the position of the capacitor, the wires and the spring. My bet is something is preventing the switch fully clicking home. It should have a pretty firm ‘snap’ to it, that you can push it further suggests it is being impeded.

PS Is your 124 a MkI or II. IIRC some MkIs may have had a different switch design. It is the 124/II I’m describing, that’s the one I know inside and out. @Mike P may have suggestions too.

 

[fran]

I used this in one I helped a friend with

RS Stock No.:797-2523

If I remember rightly, the holes line up with those already in the chassis.

 

[Mike P]

Is your switch like this one?

20240409_204510 by Michael Pickwell, on Flickr

If it is, first of all, make sure the switch contacts are clean. They can get really dirty, especially if the switch has been arcing.

If you can't see anything that's stopping the switch's moving parts from operating freely you might want to check the position of the brass roller as indicated in this pic. As a good starting point, adjust so that it's almost, but not quite, touching on the right hand side as viewed in this pic.

20240504_193808 by Michael Pickwell, on Flickr

Can you post a photo?

 

[ruckerfoad]

I have a handful of generic replacement micro switches that pick up the same hole pattern in my 124 Mk II... Micro Switch PN BZ-R88-A2. If you are in the US I will happily send you one for the cost of shipping.

 

[jan tomczak]

I had issues with the original switch when turning on/off and speed selection on my 124. Interference with tv and preamp shutdown warning…was a bit of a headache tbh. It was cleaned as advised and had a new spark suppressor fitted btw…no joy!

Purchased a micro switch from usa via eBay (no longer available) and a second one from Hanze Hifi (Holland)… both work flawlessly with none of the issues I had previously and a simple fitting into the existing screw holes.

 

[wer]

Thank you for all your suggestions, and please forgive my long silence - doctors visits interfered.
Will have a go at the weekend, but pleased to hear that replacements are available at a generic price level if needed.

 

[wer]

Started the order procedure at Handover, but terminated it when I got to postage - EUR 23 for a 50g item within the EU is more than I am prepared to pay.
So the TD124 went back on the bench. There was nothing impeding the reed, but it simply would not reliably make contact. However, when I pushed the left (slightly movable ) support towards the bearing, contact was made. Fixed it in that position with a strip of plastic, installed the new blue belt, and veil let it run overnight.

 

[wer]

It switches on and off without problem now, but listening to records is painful, because my workaround seems to couple the chassis tho the plinth, causing exaggerated rumble.
Getting a new switch from H anse (at much more reasonable postage).

 

[snowlets]

Hello WER, what are the parameters of capacitors connected in parallel to switches? My TD124 makes a lot of noise when operating the switch. I suspect it's a problem with the capacitor.
In addition, the rumbling sound of this turntable is indeed loud. I compared it to modern turntables and suspect that the motor vibration is too strong. Would it be better to replace it with a DC motor with carbon brushes, which has almost no vibration. If a constant voltage drives a DC motor, then an eddy current reducer may still be used for speed regulation. I have the idea of this renovation, but I haven't started yet.

 

[Tony L]

In addition, the rumbling sound of this turntable is indeed loud. I compared it to modern turntables and suspect that the motor vibration is too strong. Would it be better to replace it with a DC motor with carbon brushes, which has almost no vibration. If a constant voltage drives a DC motor, then an eddy current reducer may still be used for speed regulation. I have the idea of this renovation, but I haven't started yet.

The rumble will never be as low as a typical belt or direct drive turntable, but it certainly shouldn’t be intrusive. If it is you haven’t finished restoring your TD-124 yet! I’d certainly not blame the original parts or try to hack it into being something it is not. You will devalue a sought-after turntable and likely lose the aspects that made it a classic in the first place; the remarkable pitch-solidity, drive etc, a lot of that comes from the high-torque motor.

Try some of the non-destructive tweaks, e.g. the motor decoupling springs (Hanze or @Mike P ), the blue-belt (@Mike P) and treat the idler with Rubber Renue (Amazon). All will get you closer.

 

[snowlets]

I replaced the capacitor in parallel on the switch, 10NF. The switch noise seems to have decreased slightly, but it is still unbearable. I also spent a lot of money making a brass turntable to replace the deformed aluminum turntable. The use of rotary pressure technology may not achieve ideal accuracy, but it is always better than deformed aluminum plates.

 

[ruckerfoad]

There are a few sources of mechanical noise in these decks... the motor and the main bearing being the major culprits. The Woodsong thrust bearing kit is well worth the money, as are the springs vs the rubber motor grommets. If your idler is out of true the Audiosilente replacements are very good, and replacing the thrust washer for the idler can quiet things down as well.

Based on the paint color it looks like yours is a Mk II deck... is the main platter a grayish dull color, or is it painted green? If it's the former, some of the noise may be due to misalignment as the lighter alloy platter has to be centered whenever it's removed from the spindle. Switching mine to a used cast iron platter made a world of difference in noise.

 

[wer]

Following Frank Schroeder's advice I looked for silica gel inserts for the motor mounts.
Compared to the conventional mounts l used previously, this made a significant difference - motor vibration is close eliminated.
I am not competent to talk about changing to a DC motor, because I have never attempted such a transplant.

 

[Tony L]

IME most noise can be traced to the belt, step pulley and idler. I found Mike’s blue belt a game-changer as all the currently made alternatives try to be right on both the 50 and 60Hz pulley, which means they are way, way too tight on the larger 50Hz resulting in noise and belt-shedding. The blue belt is the right size and way lower tension. Much quieter and no rubber shedding. Treating the idler with Rubber Renue as linked upthread also made a good difference, it really freshens and softens up the rubber which again drops the noise floor. I may have been lucky with the motor as mine is in great shape. Patience aligning the casing pays dividends, if your motor is noisy it may well just be misaligned. I expect to fiddle with it after a full strip-down for about half an hour before I’m happy it is as quiet as it can be. Don’t over-tighten the bolts, low tension here gives the quietest results IME. Just enough to stop anything moving.