Desperately seeking Thorens TD126 mk3 gurus - let's fix this sweetie!
- Thread starter w1jim
- Start date
Umh, take a look at the innards of that motor - that's the weak link. That motor hardly looks prepared for longterm use.
The mark 1,2 & 4 are the ones to have.
Woe is me.
Dandy
Addicted Member
Take a look at the Origin Live DC motor kit, to get an idea of what is possible. http://www.turntable-power-supply.com/range.htm
I tend to think that these kits are over-priced, but they show that a DC motor and power supply is all you need. I have heard of people buying Maxon DC motors for this application, but then you need to source your own pulley, mount and power supply and control. The circuit for speed variation is quite simple if I recall correctly.
I tend to think that these kits are over-priced, but they show that a DC motor and power supply is all you need. I have heard of people buying Maxon DC motors for this application, but then you need to source your own pulley, mount and power supply and control. The circuit for speed variation is quite simple if I recall correctly.
That motor controller looks interesting though I wonder just how stable it would be. The Origin motor kit is cool but would cost far more then the TT would be worth.
I did some rough measurements - the motor spindle has a circumference of ~1.75" and the TT platter drive section has a circumference of ~20.25" which means that the motor has to spin about 11.6 times for each revolution of the platter.
At 33-1/3 RPM that means I need a motor speed of (about)385 RPM - at 45 it would be (about) 520 RPM. I don't care about 78 compatibility - and frankly would rarely use it on 45.
So I need to source a powerful and quiet enough DC motor that likes running in that range and has a shaft of about 0.075".
The motor has a pulse wheel with 72 teeth. Perhaps I could build a sensor (opto or hall effect) that could pickup pulses and feed the Thorens circuit.
Failing that I would opt for the PWM speed control device shown in the ebay link.
Any thoughts on where I could locate such a motor?
BTW - please remove the ebay link, the powers that be only want thse in the Dollars and Sense area.
Hmmm :scratch2::scratch2::scratch2:
I did some rough measurements - the motor spindle has a circumference of ~1.75" and the TT platter drive section has a circumference of ~20.25" which means that the motor has to spin about 11.6 times for each revolution of the platter.
At 33-1/3 RPM that means I need a motor speed of (about)385 RPM - at 45 it would be (about) 520 RPM. I don't care about 78 compatibility - and frankly would rarely use it on 45.
So I need to source a powerful and quiet enough DC motor that likes running in that range and has a shaft of about 0.075".
The motor has a pulse wheel with 72 teeth. Perhaps I could build a sensor (opto or hall effect) that could pickup pulses and feed the Thorens circuit.
Failing that I would opt for the PWM speed control device shown in the ebay link.
Any thoughts on where I could locate such a motor?
BTW - please remove the ebay link, the powers that be only want thse in the Dollars and Sense area.
Hmmm :scratch2::scratch2::scratch2:
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HI Jim,
Yes, I can see that the motor is really messed up. My question is bigger. Maybe your motor problem is not typical. Maybe most work fine, forever. Or, maybe the turntable has other problems.
I was asking about all the problems that have been reported. You might find that you don't want to fix this one. For example, (not trying to make you feel bad) my pristine TD125 Mk1 is just chunking along like it had just been born. Yet it is 40 years old.
I'm not at all sure your turntable is worth the effort to fix given the alternatives.
Sparky
Good news is I have a line on a couple of possible donor TTs.
Also there are a bunch of interesting motors on ebay in the 10-20 dollar range that would be tempting to try out with the aforementioned speed controller. Main problem with these is the shaft size - I'd have to machine them down or build an adapter.
These are DC motors that are speced as 1000 RPM which I'm thinking are close enough to the speed I need to be slowed down by a PWM speed controller.
BTW - the one that you referenced (at $29.95) is built and sold by Jameco for $5 less on their website (kit #67).
In some ways I have a dilemma - do I fix the TT with the original crappy motor and just wait for it to die again or bastardize this with a non-original motor and speed controller in which case it will be unsellable when the time comes to upgrade / move on.
The mk3 model has poor resale due to this design weakness anyway so the intelligent thing to do would be to part it out - but the tinkerer in me wants to make it functional.
It's not like I'm especially hurting for fine TTs - I have 6 beauties - all set up and in systems, it's just that I (like most of us) can't resist another pretty face (don't get me started about all the monster receivers, I've lost control there).
I'll have to see what parts come available in the next week or so before I consider putting it on the backburner.
Also there are a bunch of interesting motors on ebay in the 10-20 dollar range that would be tempting to try out with the aforementioned speed controller. Main problem with these is the shaft size - I'd have to machine them down or build an adapter.
These are DC motors that are speced as 1000 RPM which I'm thinking are close enough to the speed I need to be slowed down by a PWM speed controller.
BTW - the one that you referenced (at $29.95) is built and sold by Jameco for $5 less on their website (kit #67).
In some ways I have a dilemma - do I fix the TT with the original crappy motor and just wait for it to die again or bastardize this with a non-original motor and speed controller in which case it will be unsellable when the time comes to upgrade / move on.
The mk3 model has poor resale due to this design weakness anyway so the intelligent thing to do would be to part it out - but the tinkerer in me wants to make it functional.
It's not like I'm especially hurting for fine TTs - I have 6 beauties - all set up and in systems, it's just that I (like most of us) can't resist another pretty face (don't get me started about all the monster receivers, I've lost control there).
I'll have to see what parts come available in the next week or so before I consider putting it on the backburner.
Classic_CJ
Well-Known Member
I know this might seem odd to suggest, but before you opened the motor up, you didn't know it was crappy. Some selective amnesia might be useful, perhaps? :scratch2:
I'd just hold out until you find an exact replacement motor. They certainly didn't all die; a fair number have crossed my bench in the last decade with the motors still running just fine. The automation built into these models-- the arm lift, easy speed selection, motor shut off etc. make them very enjoyable 'tables to use on a practical basis. Changing to a different motor arrangement could get very involved and in any event it won't play nicely with the rest of the electronics.
Patience, virtue, all that stuff, ya know?
Good luck with it, in any event! :thmbsp:
Patience - who has time for that?
But I think you're right - I should make the investment in time and money and get the correct part and make it whole.
Those illuminated buttons and the automation sure have a lot of appeal.
I just won "THORENS TD110 WITH GRADO ZC+ CARTRIDGE - REPAIR PARTS" on ebay (you know "that auction site").
Hopefully I can salvage the motor and perhaps the tonearm for the TD126.
In preparation for the inevitable restoration of my 126 I have replaced the indicator bulbs with various color LEDs.
Maybe I'll call this the "TD126 mk3 Electronic Phoenix".
Stay tooned...
Hopefully I can salvage the motor and perhaps the tonearm for the TD126.
In preparation for the inevitable restoration of my 126 I have replaced the indicator bulbs with various color LEDs.
Maybe I'll call this the "TD126 mk3 Electronic Phoenix".
Stay tooned...
tube-a-lou
Addicted Member
Hi,
That's good news, Hope it didn't cost that much and the motor
works better, I've been following the thread, lets see what happens.
Tube
It couldn't possibly work worse!
Well I certainly hope (and think) so. The TD126 mk3 is supposed to share the motor with the TD105 and TD110 and in the off chance the pulley and mount is different I at least have the originals.
Most of the bulbs illuminating the function buttons were burnt out so I've replaced them with LEDs. On the speed buttons I used a green wide angle LED with a 1500 ohm resistor in series to illuminate the well below the switches. For the 2 tone arm "cue-up" buttons I used a red LED and for the tone arm "lift-down" I used an amber LED. They are brighter then the picture represents. The power source for the LEDs is polarized so polarity needs to be observed. The soldering is a bit sloppy at the moment and will need to be touched up once things are finalized.
Next, once I get the new motor in place I'll have to see (and hope) that the driver transistor is good.
Also, while the plinth is fairly sturdy wood, the base plate is made of plastic. I'll be either replacing or reinforcing the base with some heavier wood.
Next, once I get the new motor in place I'll have to see (and hope) that the driver transistor is good.
Also, while the plinth is fairly sturdy wood, the base plate is made of plastic. I'll be either replacing or reinforcing the base with some heavier wood.
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tube-a-lou
Addicted Member
Hi,
That's going to be a cool looking Turntable when done, I hear you about the
base and the base plate I'm looking to add some more wood going across the
base length wise to beef it up sounds kinda hallow when taped.
Tube
That's going to be a cool looking Turntable when done, I hear you about the
base and the base plate I'm looking to add some more wood going across the
base length wise to beef it up sounds kinda hallow when taped.
Tube
Dandy
Addicted Member
This is turning into a fun restoration 'Thorenstein' thread. 
I hope you end up with a really fine turntable. If possible, can you post some pics of the motor replacement when you do it?
How thick is your plastic base plate? On my TD125 MkII it is about 6mm think and fairly inert. I'd wait till your deck is working before replacing it, as adding mass or wood could mess up the suspension.
I hope you end up with a really fine turntable. If possible, can you post some pics of the motor replacement when you do it?How thick is your plastic base plate? On my TD125 MkII it is about 6mm think and fairly inert. I'd wait till your deck is working before replacing it, as adding mass or wood could mess up the suspension.
The adventure continues.
I received the parts Thorens TD110. The ebay listing said that the motor ran fast and that there was either a problem with the motor or the speed regulation circuit. I figured that at least the motor worked so that was going to be good for swaping.
Well - right and wrong. When I installed it I found that it too ran fast - way too fast, like mach 1 fastsigh.
Hmm, if the motor turns (good) then it must have something to do with the integrated motor speed sensor.
Yep - it measured open. I hooked up the scope and verified that the "new" sensor showed nothing while the original sensor showed pulses.
Now I've removed the old senor (by cracking the welds in a vice) and am epoxying the original sensor in place with paper shins to keep it centered.
See pictures of the motor with the sensor removed and the replacement sensor (along with the bad one).
To be continued!
I received the parts Thorens TD110. The ebay listing said that the motor ran fast and that there was either a problem with the motor or the speed regulation circuit. I figured that at least the motor worked so that was going to be good for swaping.
Well - right and wrong. When I installed it I found that it too ran fast - way too fast, like mach 1 fast
sigh.Hmm, if the motor turns (good) then it must have something to do with the integrated motor speed sensor.
Yep - it measured open. I hooked up the scope and verified that the "new" sensor showed nothing while the original sensor showed pulses.
Now I've removed the old senor (by cracking the welds in a vice) and am epoxying the original sensor in place with paper shins to keep it centered.
See pictures of the motor with the sensor removed and the replacement sensor (along with the bad one).
To be continued!
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