Thorens td-124 mk2 wavering pitch, help - diyAudio
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Old 15th August 2011, 11:36 PM   #1
boidos is offline boidos  Australia
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Default Thorens td-124 mk2 wavering pitch, help

Hi all, I have a thorens td-124 mk2 in my system at the moment. It has been serviced and looks great, but the pitch is wavering during playback. On the strobe this appears as very slight rocking from side to side instead of being locked in like my garrard. This is audible as a wavering of pitch during the decay of piano notes.
The platter spins very smoothly, and it has been serviced. Would anyone have any ideas as to what would cause this.

Many thanks for your time.
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Old 15th August 2011, 11:56 PM   #2
kevinkr is offline kevinkr  United States
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A couple of things come to mind, including things like a bad (eccentric) idler pulley or a main bearing that has not been lubricated correctly or is badly worn. A very loose belt is another possibility.

I started a thread ages back that has a lot of information on rebuilding a TD-124 II, and I have worked on several more since starting that thread.

I will say that it should be rock stable, mine certainly is, and I am sure yours will be once sorted out.

I'm assuming that the motor has been properly rebuilt, and everything else is in order..
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Old 15th August 2011, 11:59 PM   #3
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Hi, thanks for getting back to me. The platter spins smoothly and the bearing is well lubricated. There is also what looks like a new thrust plate. Maybe I should try a new belt or failing that a motor rebuild. Ill have a look at your thread. cheers!
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Old 16th August 2011, 05:49 PM   #4
kevinkr is offline kevinkr  United States
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Quote:
Originally Posted by boidos View Post
Hi, thanks for getting back to me. The platter spins smoothly and the bearing is well lubricated. There is also what looks like a new thrust plate. Maybe I should try a new belt or failing that a motor rebuild. Ill have a look at your thread. cheers!
Look at the idler pulley first! Also be aware that if you take the platter off of the spindle you will need to carefully center the platter again if you have the zamac non-magnetic platter. If you do not take it off and pull the assembly as a whole then depending on the gasket installed on the end cap you take the risk of blowing out the gasket when you reinstall the platter. This is all explained quite well in the thread.
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Old 19th August 2011, 01:49 AM   #5
studeb is offline studeb  United States
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You say it wavers, how fast?
Like Kevinkr says, idler and belt pulley would be first to look at.
You should be able to find the issue.
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Old 19th August 2011, 01:55 AM   #6
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Firstly it takes quite a while for the speed to settle. Then eventually visually I can describe it as once the dots stop scrolling in ether direction, they just wobble slightly from side to side if that makes any sense. Its not tighly locked like my garrard. this can be heard as a kind of subtle but slow pitch vibrato during solo piano decays.
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Old 19th August 2011, 05:00 AM   #7
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Quote:
Originally Posted by boidos View Post
Firstly it takes quite a while for the speed to settle. Then eventually visually I can describe it as once the dots stop scrolling in ether direction, they just wobble slightly from side to side if that makes any sense. Its not tighly locked like my garrard. this can be heard as a kind of subtle but slow pitch vibrato during solo piano decays.
It could be a combination of things.
I'd start with a thorough disassemble, clean, measure for wear, lube/reassemble. And this means the motor in particular.

My hunch is that the lube in the motor bearings has become paste exerting extra drag on the motor shaft as it spins.

Other items are suspect as well. Anything that spins inside a bushing requires clean/lube.

The idler wheel is also suspect until proven otherwise. Usually, the idler wheels hold up well in this model. But once in a while you can find one with a flat spot on its outer rubber. And like the other parts, the idler wheel has a bushing and it spins over a precision ground shaft. It requires some lube. There is also a thrust washer under the idler wheel. Examine that for undue wear.

It's all basic simple mechanics. things that spin in this machine have shafts and bushings. Clean and lube those things that spin.

One thing for sure, it doesn't get better all by itself. You gotta help it along.

-Steve
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Old 19th August 2011, 05:11 AM   #8
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thanks for the advice, ill check out the idler wheel and start the deep clean!
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Old 19th August 2011, 05:16 AM   #9
kevinkr is offline kevinkr  United States
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Quote:
Originally Posted by boidos View Post
Firstly it takes quite a while for the speed to settle. Then eventually visually I can describe it as once the dots stop scrolling in ether direction, they just wobble slightly from side to side if that makes any sense. Its not tighly locked like my garrard. this can be heard as a kind of subtle but slow pitch vibrato during solo piano decays.
Yes, this indicates there is a serious problem with some component in the drive train. Mine does not drift at all once fully warmed up, and runs only slightly slow for the first few minutes of operation in cold weather. Speed is extremely stable and there are no detectable pitch variations on any material.

The first thing to look at would be the idler and it is not too difficult to observe whether or not there is run out or a dent in the running surface of the idler. My comments so far have been based on the understanding that the unit was fully rebuilt, and the motor has been overhauled and all required cleaning and lubrication has been done. If such is not the case a cold motor with the belt removed may have excessive drag which would be an indication that service is required..
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