How does that work, spacer shims like the TP-60 or does it use some other mechanism?
Thorens TD150, TD150 MkII or TD160?
- Thread starter OldPolishGuy
- Start date
How does that work, spacer shims like the TP-60 or does it use some other mechanism?
muchachos
Active Member
No, there are set screws at the back which allow you to move the entire headshell top which the cartridge is mounted to forwards, backwards, up and down. It's a clever, if fiddly mecanism.
Thank you for the photos, really interesting! R/C car axles could fit the bill. I just double checked my measurements of the spindles with my micrometer, and these ones really are 2,0 mm. (The td 125 and the 320 ones are 3,0).
I wouldn't try any heat on them. I haven't needed any, and I wouldn't want to risk the plastic parts or the hardening of the spindle. Did you try bending your spindle while in place, or in a vice or something like that? I think it's best to do in place, despite the force applied to the bearings, since it should help steer the bending to about the same spots along the spindle as where it got bent in the first place. If yours snapped while in place, I'd guess it was worse off than any one of the ones I've come across.
And sorry once more - I must obviously stop fibbing from memory here. I had the measurement that one must get the error down to wrong before. It must get down to below 0,004 mm, which is why the 1/1000 mm indicator is needed. At least one of the bad motors had an error of 0,02 mm, which caused an audible clicking noise which disappeared after adjustment. It is probably easier to snap the spindle if it is more crooked than that.
Here are some photos from one of my previous jobs, on a 320. One fiddly thing when doing this is how to get hold of the spindle while measuring the excentricity, without making the spindle hop around. For that one can simply pull a short bit of a <2 mm hose over the bottom end of the spindle, so one can get a grip of it there. I use one of these:
It's just a Dremel collet, in a rubber bushing that presses it together, gripping on the bottom end of the spindle, thus:
Turn it round with your fingers, with the indicator clock at the top end of the spindle to find the worst angle, and start from there. Unfortunately, I don't have any photos of that.
Actually, what you are describing is how the tracking angle/overhang is adjusted on these headshells, not the VTA. There have been folks taking off the part of the headhell that holds the moving part horizontal, which gives an awkward way of adjusting the VTA by tilting the frontmost part of the headshell. I wouldn't recommend it, though.
tnsilver
Stereo Puppy
The roof of the headshell is hinged on a couple of screws in slots. A small pilot screw serves as a guide as it slides back and forth in the slots. Originally designed for a sliding lateral movement to support overhang settings. A simple tweak in the form of removing the small guide screw will accommodate a slight vertical tilt relatively to the headshell connector, which stays fixed to the tonearm. It's simple, circumvents the design, but nifty and effective in VTA settings (when actually required).
tubeactive
Super Member
Cool thread...Old vs. Older...
+1 on the TD-150 Mk 1 choice.
I had four or five TD-150s, still keep one around. The early arm is a sleeper, as long as you don't choose low tracking, high compliance cartridges. I used mine with a 30 gram cartridge, the Ortofon SPU GT. Anti-skating is not necessary with 2.5 gram or higher force, imho. With such a heavy cart, I employed the rear counterweight's, screw out, "sub-weight" to set the arm. The suspension is less finnicky than later Thorens. There were wooden and plastic arm boards used in production, so be aware. Either type is easy to use for better arms.
I would definitely avoid the later version arm, with that plastic ball near the bearings.
For the auto-lift preference, any manual table can get an added on "arm lift" thus avoiding any punishment to the cantilever. The original Thorens Q-Up has been reproduced and is affordable these days.
Caveats are in order when buying a vintage table of this caliber. The mentioned belt pulley motor spindle should not shake, wobble or vibrate. Visiting an automotive machine shop for help is not inexpensive. Buying from a seller/trader with good feedback and return privileges is assurance of a worthy sale/trade. Avoid mailing/shipping if possible !
While usps is gentler than UPS or FedEx, accidental drops happen, often. If you buy a table with a dust cover, there is almost a guarantee the cover gets damaged in shipping, even if the shipper uses all the proper foam and cushions. If you must have it shipped or employ the "pony express" car ride, consider putting shims under the platter to avoid any shocks to the main spindle bearing. With the two-piece platter, removing the outer platter is an even better option. Consider cushioning the tonearm significantly, in the event of internal collision. Over the years, I have splurged on some tables via mail-order. The dust covers never made it here without cracks or breaks. I am a careful packer and will never ship a working table due to these occurrences. The worst arrival had a collapsed plinth and busted dust cover. It's better to check these tables out in-person, since seeing a wobbly pulley or broken dust cover avoids the surprise and return shipping.
Best of luck scoring a vintage Thorens...
+1 on the TD-150 Mk 1 choice.
I had four or five TD-150s, still keep one around. The early arm is a sleeper, as long as you don't choose low tracking, high compliance cartridges. I used mine with a 30 gram cartridge, the Ortofon SPU GT. Anti-skating is not necessary with 2.5 gram or higher force, imho. With such a heavy cart, I employed the rear counterweight's, screw out, "sub-weight" to set the arm. The suspension is less finnicky than later Thorens. There were wooden and plastic arm boards used in production, so be aware. Either type is easy to use for better arms.
I would definitely avoid the later version arm, with that plastic ball near the bearings.
For the auto-lift preference, any manual table can get an added on "arm lift" thus avoiding any punishment to the cantilever. The original Thorens Q-Up has been reproduced and is affordable these days.
Caveats are in order when buying a vintage table of this caliber. The mentioned belt pulley motor spindle should not shake, wobble or vibrate. Visiting an automotive machine shop for help is not inexpensive. Buying from a seller/trader with good feedback and return privileges is assurance of a worthy sale/trade. Avoid mailing/shipping if possible !
While usps is gentler than UPS or FedEx, accidental drops happen, often. If you buy a table with a dust cover, there is almost a guarantee the cover gets damaged in shipping, even if the shipper uses all the proper foam and cushions. If you must have it shipped or employ the "pony express" car ride, consider putting shims under the platter to avoid any shocks to the main spindle bearing. With the two-piece platter, removing the outer platter is an even better option. Consider cushioning the tonearm significantly, in the event of internal collision. Over the years, I have splurged on some tables via mail-order. The dust covers never made it here without cracks or breaks. I am a careful packer and will never ship a working table due to these occurrences. The worst arrival had a collapsed plinth and busted dust cover. It's better to check these tables out in-person, since seeing a wobbly pulley or broken dust cover avoids the surprise and return shipping.
Best of luck scoring a vintage Thorens...
I actually was about to write something along these lines too, but skipped it, thinking those heavy trackers are a bit esoteric. But I agree, totally. At the other end of the scale though, the AT-3600 is an excellent budget cart, made for about 2,5 g - perfect for the mk I, and other 60's turntables with arms made for heavier carts.
muchachos
Active Member
Thanks for the measurements. The collet device to rotate the spindle from below is quite clever. I did succeed in breaking the shaft when it was in place - it went from springing back to the state of the original bend to snapped much more quickly than I expected. The break was also below the bearings at the top, right where the shaft met the magnet inside. Seems to suggest that the bearing wasn't holding it in place as I attempted to bend it back. Live and learn.
Figured I'd share here my progress on replacing the motor spindle - at risk of derailing the thread, yes, but I haven't seen many pics of this sort of thing around the 'net, so it's worth sharing.
Starting with the motor disassembled. The rivets can be removed by filing the edges slightly, then pulling em out with a pliers. The motor will now come apart. The red shaft puller is good for removing the pulley from the axle. Got it for about $10 from Aliexpress. Not sure how Thorens attached them, but they will not come off by hand after 50 years! The shaft is from a hobby store - 2mm Tamiya model airplane prop shaft, which is in fact hollow in the middle. Couldn't find anything solid in stainless steel, so this should work.
The motor magnet shaft has to be removed on this one and replaced with a new one. A few chips came out of the magnet from around the shaft as well, since the break was right where the shaft enters the magnet. The bushings were clearly not enough to bend this one back in place. Kept track of these chips to reattach later. I gently drilled around the shaft to clean the 'nocks' inside the shaft which fixed the original one in place.
Installed and cut to length. Filed the cut end down to neaten it. This is at the top - allowing me to install a thrust bearing kit if I need to on the neat factory cut edge.
Carefully glued the chips off the magnet back in place with superglue. This is a pain.
Reinstalled nylon bushings, and put magnet in place.
Finally installed in the motor. Next step is to get some 15mm spacers from the electronics shop and appropriate bolts to put it back together. I'd like to bolt it rather than reinstall the rivets with JB Weld or similar so I can more easily adjust the alignment and spacing of the two motor halves. I haven't tested this yet, but it rotates smoothly and I do expect it to work when I put it back together. So all hope is not lost if your motor shaft is bent - it just might be a little bit of fiddly work! I think that the 160 motors seem to have a shaft which is easier to remove from the magnet, as this one is clearly not designed to be taken out. This is probably the biggest downfall of this method, as you will damage the magnet as you remove it. But, if the motor is a write-off otherwise, you could do worse.
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Hope we will be excused for the derailing of the thread! Thanks for the photos, they really are rare and interesting.
Just two quick notes: As you describe your breaking of the spindle, I think you may have overdone it a bit. I really meant it should be more or less massaged into position. Do not press so hard you can measure any effect after just one attempt, but press it firmly, in several steps, just to achieve a miniscule measurelable correction. The spindle is made of hardened steel, which makes it brittle, but it can be done in small steps. The second last thing you want to do (apart from breaking it) is to overdo your adjustment. The job should take about one half an hour.
And I would probably try a sequence of lapping films at the new spindle, where the nylon bearing will run.
Just two quick notes: As you describe your breaking of the spindle, I think you may have overdone it a bit. I really meant it should be more or less massaged into position. Do not press so hard you can measure any effect after just one attempt, but press it firmly, in several steps, just to achieve a miniscule measurelable correction. The spindle is made of hardened steel, which makes it brittle, but it can be done in small steps. The second last thing you want to do (apart from breaking it) is to overdo your adjustment. The job should take about one half an hour.
And I would probably try a sequence of lapping films at the new spindle, where the nylon bearing will run.
Just one fun biological fact, for somebody wondering if they have a warped spindle, and who of some strange reason has mislaid his or her 1/1000-mm-indicator clock: The pressure sensitivity of a human nail is said to be ca 1/1000 mm (!), which means that all of these adjustments could in principle be done by hand. The problem is just that one's nails lack a usable scale for differentiating between the measurements. The gist of this all is that it is perfectly normal to sense an eccentricity of the pulley with your finger nail while the motor is rotating. The Thorens pulleys are built with so much slack - especially the 160 ones with the clutch. Interestingly enough that could could be seen as an argument for the simpler 150 design, making for less of vibrations into the belt - of course instead giving the motor a more difficult load at start. But any self respecting Thorens (or Linn) owner gives the platter a slight nudge when starting up anyhow, so that shouldn't matter.
With the clutched spindle removed, the unevenness of the rotation of the spindle should be barely notable by your nails, but even a slight wobble can still be within acceptable tolerances. More than that is a bad sign. I don't have my measurements of the 150 spindle around, but don't expect to be able to adjust the wobble of that one at the pulley down to 0.004 mm, since the pulley in itself probably is made with slacker tolerances (I wouldn't advice to remove the pulley, unless @muchachos has an easy method for doing that). But at least now you know what to aim for.
tnsilver
Stereo Puppy
I've never noticed that other than with a bent motor spindle. In fact, when they spin they look rather stationary to me, which likely means they're quite perfectly aligned. Why is that? Is the pulley eccentric? Thorens couldn't drill a straight bore?
Honestly this don't make much sense as a design decision. You know those round motors were used interchangeably with some of the low run TD-165 models, yet no spec differences. The Sonceboz triangle motors are press fit with brass (possibly oilite) bushings as opposed to plastic (likely Nylatron) of the earlier motors. It's just that 'slack' doesn't actually appear to be part of the design. Not to me anyway.
It is just a question of reasonably acceptable tolerances in different parts. Remember the TD150 was originally designed as Thorense's "low budget" replacement for the TD-135, for about half the price. The motor itself must of course run clean, with tight tolerances, but the effect of an eccentricity of some 0,05 mm at the pulley can be considered to be damped out in the belt. I don't say the pulley is badly aligned, only not as extremely tight as the spindle.
If you look closely on any one of the plastic pulleys, the ones without the clutch, as in 165, or with the clutch, as in 160 and 125, you can clearly see the joint from the mould it was cast in, going axially across the pulley. I haven't seen any plastic pulley without it, and it can be almost 0.1 mm high - much larger than the tolerances I'm talking about. Obviously the designers at Thorens didn't consider that much of an error any problem. And with the clutch, you must also have some slack for it to work, which adds to the unevenness of the pulley, at least when you try to locate a crooked spindle. That is why I think the turned aluminium pulley in the 150 could in fact be a better design - it is after all more in line with what was to come in the later Thorens clones, like the Linn and the other British lookalikes.
The eccentricity of course isn't visible to the naked eye while the motor is running, and the one in the clutch should be evened out by the tension of the belt during its rotation, but it can still be felt by the nail of your thumb or an indicator clock. If the effect is in fact audible can be discussed. I think the belt damps it out enough to not be measurable or audible in traditional wow/flutter terms, but I do think it nevertheless adds to resonances and oscillations in the belt - things that came more in focus long after these machines were made.
tnsilver
Stereo Puppy
That's interesting. I'll take a closer look at some 125 and 160 pulleys for that axial joint. It may refresh my memory. IIRC I've never seen it, but I've never put a dial indicator to it either (I might need to grow some thumb nail though, as the thought of using it as a tool had never crossed my mind 
).
).
doctor fuse
Super Member
I have rarely seen a 150 in my neck of the woods, but I no longer use my 160 because putting my RB300 or G-707 arm on it would apparently involve cutting part of the metal chassis, which I don't want to do. Maybe one day.
That's interesting. I'll take a closer look at some 125 and 160 pulleys for that axial joint. It may refresh my memory. IIRC I've never seen it, but I've never put a dial indicator to it either (I might need to grow some thumb nail though, as the thought of using it as a tool had never crossed my mind
Just to be precise, what you are looking for isn't a joint in the pulley, but an impression from the mould it was cast in. I'm not saying the joint is there on every pulley, but many enough for me to have noticed them as something recurring.
I've only got the 150 I always keep around as one of my reference machines at home right now. Of course the joint wasn't there on the photos I had saved from previous jobs, so i can't show you what you could look for.
I was wrong on the 125, though - obviously their pulleys are different, having the electronic speed control.
I really wouldn't bother. Too big an operation on an already good enough TT, just to achive a dubious result unless you're just into the tinkering. The Rega is a bit on the heavy side for the 160, making for problems with the suspension, only worsened since the added length of it would put the weight of the arm further away from the centre balance point in the subchassis. Better to save the arms for something they fit better on in the first place. If you aren't happy with the 160 I think you'd replace it with something else entirely - I doubt the arm would be enough of a problem. If you still want to replace the arm, the entire Linn-inspired generation apart from the Regas have the same length as the Thorens arms. A much easier replacement.
muchachos
Active Member
Thanks for these pointers. I certainly did overdo it, but I had this problem some time ago before sourcing a replacement motor with a 165. Never had any luck with straightening it by hand, but I didn't know this yet! I'm curious what your dial indicator set up looks like, as I do not have this equipment on hand.
I found the pulley quite easy to remove actually with a 2mm shaft puller designed for RC car motors - the red apparatus pictured here.
This would be between the nylon bushing and the brass bearing mounted inside the motor you mean, with the intention of reducing the running friction? I think I have some mylar sheet around which might work well for this. May see how this works once I get the motor reassembled, or a spindle thrust bearing kit from ebay for support from below to accomplish much the same.
Nothing very fancy, just the indicator on a stand, like this. You don't necessarily need the stand this sturdy - the first motors I did I just held the indicator firmly pressed against the top plate with a piece of wood under it to get it in the right height. But having some sort of stand makes it much easier.
Adjust the measuring tip against the top of the spindle, at the 0-point on the dial. Turn the spindle round with the collet from below, to see how much the dial moves. Quit working the spindle when you reach ± 0,004 mm. That is enough, better not to risk overdoing it and perhaps needing to redo things in the opposite direction.
I don't know if you perhaps misunderstood me? The lapping film is the finest grade "sanding paper", with diamond dust, graded for optical and fine mechanics work. Perfect for polishing the bearing area of spindles. (Polishing sintered bushings ruins them, but you already knew that. Only polish the spindle).
muchachos
Active Member
I will look into that! Thanks for the photo of your dial indicator setup - seems a bit clearer. Any reason you'd avoid using a basic metal polishing compound for this sort of work? That was my initial plan.
Pedantery, while you're at it... A common metal polish should be good enough. That's what I use for most of these jobs myself.