Desperately seeking Thorens TD126 mk3 gurus - let's fix this sweetie!

[w1jim]

HELP!

I just picked up a pretty TD126 mk3 electronic today and damn - the motor doesn't spin.
The cueing works and the speed switches (at least the ones with good bulbs) light up appropriately.

I opened it up and everything looks clean (no burnt parts). I unplugged the motor from the PCB and fed 8.5vdc into it and got no motion out of it. Also I got no reading on the ohm meter. I'm guessing the motor is toast and want some suggestions before I attempt opening it up.

Also, some of the small bulbs that illuminate the switches are out - where can I source these.

Any suggestions would be greatly appreciated.

JimB

 

[w1jim]

I'm realizing that this may be a challenge but I figure I'll still be ahead of the game - here's a picture of the cartridge it came with - a Monster Cable Genesis 2000 (LOMC) in great condition. This is holy grail stuff!

And a picture of the underside.

 

[Tucker99]

I have not owned the MkIII version but I have read that they are difficult to sort electronically...the stuff you read about simple re-caps for the MkII do not apply to the MkIII.

So, best I can officer is my good wishes, and keep us posted on what your try and how the project works out.

Not sure what you paid but if you get it sorted the Thorens TTs are, of course, a nice table.

What tonearm is on it?

 

[w1jim]

Not being fluent in the world of Thorens I'm thinking it is the OEM one - see picture below.
If I can't fix this then my options are either to part it out (which I'm not too keen on) or to figure out a way to put another motor and speed regulation circuit in it.
Hopefully someone with specific experience in these will chime in soon.
Sorry about the dust - it's in the not-quiet-spotless O/R right now.

 

[Classic_CJ]

I unplugged the motor from the PCB and fed 8.5vdc into it and got no motion out of it. Also I got no reading on the ohm meter. I'm guessing the motor is toast and want some suggestions before I attempt opening it up.

Nearly all Thorens motors are AC motors, not DC, so feeding in DC will lock it up magnetically, not make it turn. Furthermore, they may be multi-phase motors, which means you can't even run plain ol' AC in from a transformer and make 'em go. The circuit board you have there will contain the drive circuitry for the motor, so that needs to be working.

However, the motor should show continuity (an ohm reading) on at least some combination of the leads. If it reads open on all combinations, then sadly it is bad.

I agree, try to fix this if you can, it's a superb machine.

 

[Dandy]

I agree that you should go slow and investigate repairs before going down the parting out route.

If motor turns out bad, then you should be able to find a replacement with patience. Alternatively, you could put in a DC motor, with separate speed control. I once played around with a DC motor on a TD160.

The quality of these decks lies in the high quality mechanical construction of platter, suspension, chassis etc.

 

[Dandy]

Places to look for a replacement motor--

Thorens part number Z4225026 refers to the same motor for these models: TD 105-126MKIII /104/110/115

Source: http://www.theanalogdept.com/thorens_part_nums.htm

 

[w1jim]

Nearly all Thorens motors are AC motors, not DC, so feeding in DC will lock it up magnetically...

That was my initial thought until I read post #5 from this thread:
http://www.audiokarma.org/forums/showthread.php?t=311583

Which basically says:
the TD126 was a high class Thorens model, with the MkIII being the first 126er to sport an electronically regulated DC motor (instead of AC synchronous)

None-the-less I get an open on the wires that appear to be the drive leads and sending the DC to the motor doesn't have any effect.

I'm thinking my best / only bet at this point is to see if I can open it up and look for something obvious like worn brushes.
I also suspect that the driver transistor might be blown but I have yet to lgive the PCB much scrutiny.

It is a beauty though!

 

[ehoove]

I believe the Mk III was the only version to use the Flywheel DC Motor, and some think this is a weak link. My MkIII runs perfectly and is a solid keeper in my mind, although it has a Signet AK50 arm on it while yours has the Thorens TP16 MkIII arm on it.
Regards,
Jim

 

[tube-a-lou]

Hi,
Working in my TD125 MK2, I took the motor apart completely, there's was a wire
touching one another inside, I used some shrink tubing to isolate the wires inside
when I put it back together it worked, I know the there's three rivets holding it
together, I used three small screws and nuts with Lock-tite to hold them on. So
far no problems and that was 2 years ago. and I would change all the electrolytics
on the boards, hopefully that should get it going.

Tube

 

[w1jim]

Places to look for a replacement motor--
Thorens part number Z4225026 refers to the same motor for these models: TD 105-126MKIII /104/110/115

Dandy-
Thanks for your help - I've sent a request to the US distributor but I'm not very optimistic.
JimB

 

[Dandy]

I wonder if the PCB is more likely to have failed than the motor. Don't know though, and I see the point of making sure you have a good motor first. If it looks to be shorted, I'd follow tube-a-lou's thoughts.

You could also see if there is more info on this model on the analoguedept website. That site is pretty reliable on Thorens decks. Failing that, ask for help on a German hifi website as Thorens decks are best known in Europe.

Hopefully you'll soon have it going!

 

[tube-a-lou]

Dandy-
Thanks for your help - I've sent a request to the US distributor but I'm not very optimistic.
JimB

Hi,
I don't think the US distributor would help, it might be a different
company now running things now, but you can try.

Tube

 

[guiller]

Manuals can be freely download from here: http://www.vinylengine.com/library/thorens/td126.shtml

 

[w1jim]

Thanks for all the help but frankly I'm not very hopeful - at least until I open up the motor and check the driver transistor.
I already snagged the SM from VinylEngine (and hifi-manuals.com) - though I wish I could read technical German or any German for that matter.
I know there's got to be a way to make this functional.

 

[Classic_CJ]

the TD126 was a high class Thorens model, with the MkIII being the first 126er to sport an electronically regulated DC motor (instead of AC synchronous)

None-the-less I get an open on the wires that appear to be the drive leads and sending the DC to the motor doesn't have any effect.

I'm thinking my best / only bet at this point is to see if I can open it up and look for something obvious like worn brushes.

That info on this model is correct-- I pulled the manuals this time to verify, and indeed the MK I & II were AC motors, and the III is a DC motor. The red and yellow leads should be the drive, and the remaining two are the tacho output back to the board.

You may indeed luck out and have an oxidized commutator-- I had a Dual direct-drive DC motor about a year ago where this was the problem, and burnishing the commutator surface got it going again.

BTW, the manual indicates that drive voltage for the 33 RPM speed is about 1.7 volts, so feeding 8 volts in certainly should have made it go if it was going to. However, with enough oxide on the commutator, that could easily block that high a voltage, and would certainly give a very high or open reading on an ohmmeter.

 

[w1jim]

Got the motor out and opened up today. It looks like the brushes - which are really just metal "fingers" that rub against a commutator disc are burnt off.
Maybe someone left the motor on and running for an extended period (or with a substantial load) - anyway, I doubt the motor can be repaired and my best bet is to canibalize a TD105 or TD110 for the correct part.
Stay tooned!

 

[mech986]

Got the motor out and opened up today. It looks like the brushes - which are really just metal "fingers" that rub against a commutator disc are burnt off.
Maybe someone left the motor on and running for an extended period (or with a substantial load) - anyway, I doubt the motor can be repaired and my best bet is to canibalize a TD105 or TD110 for the correct part.
Stay tooned!

Post some pics of the brush/fingers and commutator and let's see what they are like. If the commutator is still intact, there might be a way to replace with some type of light brass spring with a flat piece of brass silver soldered onto it.

Slot car motors used a brush type setup with coil or spring wire long ago. Maybe something could be rigged up.

 

[w1jim]

Here are some close-ups. I just think it's a crappy design and it would be cool to replace this with a "real" motor without spending more then the whole thing would be worth.
Still open to suggestions but I think I'll be looking for a parts donor.

 

[Classic_CJ]

I would only try to rebuild one of these if I was desperate - cleaning the commutator is one thing, trying to make new brushes that would be reliable, not create excessive electrical noise etc. is more than slightly difficult. This motor must run precisely at a very slow speed; the engineering is different than for other more conventional types of DC motors. Try to locate a good motor from a parts unit, NOS or other source would be my recommendation. It might take a while, but it would end up being far less hassle IMO.