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Is there a TT bearing expert in Vic? the Luxman beckons..


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Hi all,

 

I'm thinking of taking another run at fixing my PD 350. The TT has so far had pretty much every electronic component changed including caps and all controller ICs. Stuart from SGR spent many hours working on this and could not fix the speed issue... the Ghost in the Machine.

 

After all that time, Stuart concluded that the likely cause is in the bearing. After running for an hour or several hours at correct speed, (depending on the environmental temperature), the platter picks up speed and races along spinning very quickly. It seems that the bearing might be heating up the electronics responsible for speed control somehow causing the speed anomaly after warm up time has elapsed.

 

Now I need to have someone diagnose what my bearing is doing and how it is causing this heat/friction so a fix can be applied...

 

I know you're probably all sick of hearing about this freaking Luxman but, everytime I look at it sitting idle...well, I just can't give up on it.

 

So, is there somone who knows this stuff...who is the bearing king?

 

Cheers

 

M

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I have now been spinning records on my lazarus-like Luxman for about 6 hours...It has been rock solid, not a waver, not a hint of speed anomaly. And...It sounds wonderful! Unbelievable I know but thi

Hi Unclemack, Nice turntable the Luxman PD 350, too good to scrap. I'm based in Nowra NSW and can arrange free shipping from Southern Cross and return by coach, Premier Motor Service. Send it up an

Well, It's all packed up and on the way to Vince... I am cautiously optimistic.   Cheers   M

Hi all,

 

I'm thinking of taking another run at fixing my PD 350. The TT has so far had pretty much every electronic component changed including caps and all controller ICs. Stuart from SGR spent many hours working on this and could not fix the speed issue... the Ghost in the Machine.

 

Cheers

 

M

 

So Stuart spent "many hours" working on this ... did he charge you for his time?

 

If he didn't ... you're a very lucky man! ;)

 

If he did ... I suggest you've already spent more than the TT is worth - with the need to spend more, to fix the problem.

 

So why not put this further expenditure towards a "decent" TT - that actually works - and give the Luxman to a cash-strapped vinyl enthusiast who likes fixing things? :)  That way you:

  1. get some karma points, and
  2. get to enjoy your listening to vinyl!

 

 

Regards,

 

Andy

Edited by andyr
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Bad luck M. I can't recommend anyone but I have a couple of questions:

Have the speed adjusting pots been replaced?

Does this thing have a strobe light?

Is the speed unstable with and without the vacuum hold down on?

Is the speed unstable on both 33 and 45 speeds?

What belt are you using?

Edited by Telecine
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So Stuart spent "many hours" working on this ... did he charge you for his time?

 

If he didn't ... you're a very lucky man! ;)

 

If he did ... I suggest you've already spent more than the TT is worth - with the need to spend more, to fix the problem.

 

So why not put this further expenditure towards a "decent" TT - that actually works - and give the Luxman to a cash-strapped vinyl enthusiast who likes fixing things? :)  That way you:

  1. get some karma points, and
  2. get to enjoy your listening to vinyl!

 

 

Regards,

 

Andy

Andy,

 

I have a "decent" turntable atm. I purchased an Acoustic Signature Challenger TT and am enjoying it very much. So, I am enjoying vinyl once again. Is this worth pursuing? I have no idea and I suspect that I am being ruled by my heart on this rather than my head. The Challenger works beautifully but is a sterile looking piece of equipment. the Luxman is simply a gorgeous TT, more a gorgeous boat-anchor at this point I guess, but when it works, its hard to beat both from a sonic and aesthetic viewpoint.

 

I find it hard to fathom that there is no-one that can inspect a bearing and diagnose whether it's at fault in any way...

 

Cheers

M

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So Stuart spent "many hours" working on this ... did he charge you for his time?

 

If he didn't ... you're a very lucky man! ;)

 

If he did ... I suggest you've already spent more than the TT is worth - with the need to spend more, to fix the problem.

 

So why not put this further expenditure towards a "decent" TT - that actually works - and give the Luxman to a cash-strapped vinyl enthusiast who likes fixing things? :)  That way you:

  1. get some karma points, and
  2. get to enjoy your listening to vinyl!

 

 

Regards,

 

Andy

 

he does have a very nice acoustic signature turntable, and can understand why he wants to keep the luxman.

 

M, as Turantable said, contact Duc (Lovetube).

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Bad luck M. I can't recommend anyone but I have a couple of questions:

Have the speed adjusting pots been replaced? No but they have been checked and ruled out as a cause.

Does this thing have a strobe light? No

Is the speed unstable with and without the vacuum hold down on? Yes

Is the speed unstable on both 33 and 45 speeds? Yes

What belt are you using? I think it's the original belt. it's the one that came with the TT.

Thanks Telecine...

 

Cheers

 

M

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he does have a very nice acoustic signature turntable, and can understand why he wants to keep the luxman.

 

M, as Turantable said, contact Duc (Lovetube).

2 for Duc....

 

Thanks John and TT, I'll give it a shot.

 

Cheers

 

M

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Andy,

 

I have a "decent" turntable atm. I purchased an Acoustic Signature Challenger TT and am enjoying it very much. So, I am enjoying vinyl once again. Is this worth pursuing? I have no idea and I suspect that I am being ruled by my heart on this rather than my head. The Challenger works beautifully but is a sterile looking piece of equipment. the Luxman is simply a gorgeous TT, more a gorgeous boat-anchor at this point I guess, but when it works, its hard to beat both from a sonic and aesthetic viewpoint.

 

I find it hard to fathom that there is no-one that can inspect a bearing and diagnose whether it's at fault in any way...

 

Cheers

M

 

 

I guess if I had to sum up why I persist with the Luxman...

 

Sorry, UM - I had no idea your Luxman was such a top TT when it was released.  Or that you had another good TT as well.  :sorry:

 

In terms of aesthetics - yes, I agree the Luxman is more attractive than the "thing" in the RHS pic ... but it still doesn't exactly float my boat. ;)

 

BTW, if you compare the listening experience from the Acoustic Signature Challenger vs. the Luxman (when it's working properly, before it starts racing), which gives you the more pleasure?  By which I basically mean ... which TT communicates the emotion in the singer's voice better than the other?

 

Re. your complaint that it can't be too hard to inspect a bearing, to see if there's anything wrong with it ... without wanting to contradict Stuart (because he is da Man! :D ), as I had a similar speed problem with my LP12 recently - which turned out to be the Lingo speed controller - I would've thought it is more likely there is a something wrong with your Luxman motor controller, rather than the bearing.  (My problem resulted in the Lingo needing to go back to Scotland, for a compete overhaul! :( )

 

 

Regards,

 

Andy

Edited by andyr
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Sorry, UM - I had no idea your Luxman was such a top TT when it was released.  Or that you had another good TT as well.  :sorry:

 

In terms of aesthetics - yes, I agree the Luxman is more attractive than the "thing" in the RHS pic ... but it still doesn't exactly float my boat. ;)

 

BTW, if you compare the listening experience from the Acoustic Signature Challenger vs. the Luxman (when it's working properly, before it starts racing), which gives you the more pleasure?  By which I basically mean ... which TT communicates the emotion in the singer's voice better than the other?

 

Re. your complaint that it can't be too hard to inspect a bearing, to see if there's anything wrong with it ... without wanting to contradict Stuart (because he is da Man! :D ), as I had a similar speed problem with my LP12 recently - which turned out to be the Lingo speed controller - I would've thought it is more likely there is a something wrong with your Luxman motor controller, rather than the bearing.  (My problem resulted in the Lingo needing to go back to Scotland, for a compete overhaul! :( )

 

 

Regards,

 

Andy

Hi Andy,

 

If you mean the speed control ICs then they have been replaced with new ones bought from Germany and the US. The speed adjustment pots have been checked and cleaned and found not to be at fault. I think the bearing theory is reasonably sound as the TT works fine until it heats up and it's likely that the heat is coming from a mechanical source which is, in turn, causing an electronic malfunction. Again, it's all about proper diagnosis and this is why I am looking for someone who can conclusively determine if and why the bearing is not functioning correctly... 

 

Cheers

 

M

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Hi Andy,

 

If you mean the speed control ICs then they have been replaced with new ones bought from Germany and the US. The speed adjustment pots have been checked and cleaned and found not to be at fault. I think the bearing theory is reasonably sound as the TT works fine until it heats up and it's likely that the heat is coming from a mechanical source which is, in turn, causing an electronic malfunction. Again, it's all about proper diagnosis and this is why I am looking for someone who can conclusively determine if and why the bearing is not functioning correctly... 

 

Cheers

 

M

 

Hi UM,

 

By "speed controller" I mean the totality of the electronics driving the motor.  In my case, with the LP12, this is an external box - the Lingo.  My problem could've been caused by something heating up (a resistor?) and affecting some other component in the circuit.  I have no idea; it was intermittent and the local Linn dealer first of all said there was nothing wrong with the Lingo - luckily, he then tried it again the next day and "found" what I had told him was the problem! ;)

 

It seems to me that if the bearing itself was heating up - you said after a few hours - then:

  1. I find it hard to see how this would, in turn, heat up speed-control circuit components (and cause an electrical malfunction) ... unless in the Luxman, they are tightly packed around the bearing?
  2. The heat in the bearing would surely have a negative effect on it - so it would no longer run smooth?

Can you remove the speed control components from the plinth into an external box (like many TTs have! ;) ) so bearing heat can be discounted?

 

 

Regards,

 

Andy

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Hi UM,

 

By "speed controller" I mean the totality of the electronics driving the motor.  In my case, with the LP12, this is an external box - the Lingo.  My problem could've been caused by something heating up (a resistor?) and affecting some other component in the circuit.  I have no idea; it was intermittent and the local Linn dealer first of all said there was nothing wrong with the Lingo - luckily, he then tried it again the next day and "found" what I had told him was the problem! ;)

 

It seems to me that if the bearing itself was heating up - you said after a few hours - then:

  1. I find it hard to see how this would, in turn, heat up speed-control circuit components (and cause an electrical malfunction) ... unless in the Luxman, they are tightly packed around the bearing? Yeah. I believe that the affected components are in reasonably close proximity to the bearing housing.
  2. The heat in the bearing would surely have a negative effect on it - so it would no longer run smooth? Maybe, maybe not. That's where an expert is needed.

Can you remove the speed control components from the plinth into an external box (like many TTs have! ;) ) so bearing heat can be discounted? Many TT's now maybe but back in '77 it wasn't as common I guess. 

 

Regards,

 

Andy

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Hi UM,

 

By "speed controller" I mean the totality of the electronics driving the motor.  In my case, with the LP12, this is an external box - the Lingo.  My problem could've been caused by something heating up (a resistor?) and affecting some other component in the circuit.  I have no idea; it was intermittent and the local Linn dealer first of all said there was nothing wrong with the Lingo - luckily, he then tried it again the next day and "found" what I had told him was the problem! ;)

 

It seems to me that if the bearing itself was heating up - you said after a few hours - then:

  1. I find it hard to see how this would, in turn, heat up speed-control circuit components (and cause an electrical malfunction) ... unless in the Luxman, they are tightly packed around the bearing? Yeah. I believe that the affected components are in reasonably close proximity to the bearing housing.
  2. The heat in the bearing would surely have a negative effect on it - so it would no longer run smooth? Maybe, maybe not. That's where an expert is needed.

Can you remove the speed control components from the plinth into an external box (like many TTs have! ;) ) so bearing heat can be discounted? Many TT's now maybe but back in '77 it wasn't as common I guess. 

 

Regards,

 

Andy

 

 

If you can't find a "bearing expert" then I suggest if you take up my suggestion to externalise the motor controller, you will then at least be able to decide whether there's a problem with the bearing ... or the speed control circuitry. ;)

 

Yes, externalising the motor controller will make your Luxman non-standard - and so, potentially, reduce its "desirability" and therefore resale value - but I suggest it has little resale value in its current state! :lol:   However, I suggest you won't get much change out of 6 or 700 dollars, to put the circuitry into a nice case, with all the work involved.  And all that will do is confirm whether the bearing is the problem ... or the speed control circuit.  You'll then have further money to spend on one or the other, to fix the problem.

 

 

Regards,

 

Andy

Edited by andyr
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A turntable bearing heating up enough to affect speed control electronics? You are living in la la land.

ron

instead of mocking someone, how about offering some advice

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I know lots of bearing experts.

Checking and monitoring the temperature is the first port of call.

(unless it's noisy..........then you know you have a problem)

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I know lots of bearing experts.

Checking and monitoring the temperature is the first port of call.

(unless it's noisy..........then you know you have a problem)

Thanks LP,

 

The bearing seems to run very freely and is silent from what I can tell although I haven't had a stethoscope to it. I assume I'd have to get one of those thermometers to check the temp... Is there someone you could put me onto regarding this?

 

Cheers

 

M

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Thanks LP,

 

The bearing seems to run very freely and is silent from what I can tell although I haven't had a stethoscope to it. I assume I'd have to get one of those thermometers to check the temp... Is there someone you could put me onto regarding this?

 

Cheers

 

M

sorry to hear you have some problem with this Luxman again .

some advise for you M.

don't get anything's you just thrown your money away. just get it fix proberly by a turntable expert instead of a bearing expert . your problem have nothing's to do with your bearing as other have spoted it.

 

Duc

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Sorry to hear this problem unclemack, Im in Manly ATM and here is my $0.01 cent worth of input even though it might not apply to your issue or resolve TT bearing issues.

 

In my world( High speed Printing & not in TT world), bearings over heat for the following reasons:

 

there is no lubricant or the lubricant has dried out, this normally binds and cease the bearing, therefore it either requires lubrication or the bearing needs to be replaced

 

They are subjected to abnormal loads and often the bearing will cease to operate or lock up due to other mechanical devices failing!

 

Never has a bearing problem increases the speed of the device!

 

If a device suddenly increase speed, its normally an electronic  driver issue or a control issue, therefore I still believe there is something wrong with the speed logic control.  To test this,  is there a way to run the motor without speed control?  if this is possible then it will prove whether the logic and driver is still at fault.

2ndly I dont like pots period, cleaning them will have no effect on the wearing issues you have with typical mechanical pots, Some pots are loaded with conductive grease, so cleaning it will remove that grease and push it outside operation specs.

I have experimented with enough pots and all different type pots to come to this conclusion.  In order to get to the bottom I suggest you replace the pots regardless of what advise you have had, this way every possibility is covered. 

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The bearing is not heating up. 

 

It's not heat transfer from the bearing, it's the actual drive chip that is generating the heat and it seems to hit a point there it gets into thermal run-away and then loses the plot.

 

All the control chips have been replaced including the motor drive IC. I've monitored all the power supply rails and can't fault them, I've replaced any of the caps that I suspected might be the cause and the speed control pots have been replaced.

 

I'm not sure that the issue is electronic. Without the platter on, the problem never occurs. Maybe the bearing has more friction than normal, causing excess load on the drive IC? Could be the motor also, but I have had that apart and it looks fine.

 

Of course, you could probably "fix" it by just attaching a big heatsink to the drive IC, although I don't consider that a real fix, as there is some fundamental problem there at needs to be found. 

 

I heated the drive IC up using a hot air gun and a 1" tube (so that only the IC was heated), and the platter spins like crazy instantly. So if we can find what is causing the drive IC to heat up, then we can fix it. Any ideas guys?

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A likely candidate that may not have been checked, the speed change relay (I assume that it has one. The cheaper turntables from that era had a mechanical switch but the better ones often used a relay).

Bad speed change relays and speed trim pots are the only components that I have heard of that can make a 'vintage' turntable run 'insanely fast'. It will most likely be near the buttons on the control board. Of course a service manual with a circuit diagram would help a lot but they don't seem to be available anywhere online so it is best guesses from me.

Edited by Telecine
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A likely candidate that may not have been checked, the speed change relay (I assume that it has one. The cheaper turntables from that era had a mechanical switch but the better ones often used a relay).

Bad speed change relays and speed trim pots are the only components that I have heard of that can make a 'vintage' turntable run 'insanely fast'. It will most likely be near the buttons on the control board. Of course a service manual with a circuit diagram would help a lot but they don't seem to be available anywhere online so it is best guesses from 

 

Thanks Stuart for setting me straight. I wrongly interpreted the fault as a bearing issue... Thats what happens when I try to involve myself in matter above my paygrade! :)

 

Telecine, I have a service manual but the site won't let me attach it to this message so if you PM me your email addy, I'll send it to you..

 

Cheers

 

M

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Thanks Stuart for setting me straight. I wrongly interpreted the fault as a bearing issue... Thats what happens when I try to involve myself in matter above my paygrade! :)

 

Telecine, I have a service manual but the site won't let me attach it to this message so if you PM me your email addy, I'll send it to you..

 

Cheers

 

M

PM sent.

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The bearing is not heating up. 

 

It's not heat transfer from the bearing, it's the actual drive chip that is generating the heat and it seems to hit a point there it gets into thermal run-away and then loses the plot.

 

All the control chips have been replaced including the motor drive IC. I've monitored all the power supply rails and can't fault them, I've replaced any of the caps that I suspected might be the cause and the speed control pots have been replaced.

 

I'm not sure that the issue is electronic. Without the platter on, the problem never occurs. Maybe the bearing has more friction than normal, causing excess load on the drive IC? Could be the motor also, but I have had that apart and it looks fine.

 

Of course, you could probably "fix" it by just attaching a big heatsink to the drive IC, although I don't consider that a real fix, as there is some fundamental problem there at needs to be found. 

 

I heated the drive IC up using a hot air gun and a 1" tube (so that only the IC was heated), and the platter spins like crazy instantly. So if we can find what is causing the drive IC to heat up, then we can fix it. Any ideas guys?

 

 

Just throwing ideas around, so please excuse ignorance because its a hard to not see patient and also have no service manual...

 

Its great that we have worked out that increasing the heat on the driver chip increases speed.  So with the belt off the speed stays constant and doesnt increase speed.  Is the bearing easy to dismantle to have the lubricant replaced, just like a LP12 bearing?  If so would you think that replacing the lubricant is considered a possibility of resolving the issue?

 

Im not sure what type of motors that are used on this Luxman, so I cant rule the motor out either. 

 

If lets say the load is causing the motor heat up the driver IC, the motor in most instances will also rise in temp.

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Hi Unclemack,

Nice turntable the Luxman PD 350, too good to scrap.

I'm based in Nowra NSW and can arrange free shipping from Southern Cross and return by coach, Premier Motor Service.

Send it up and I will see what I can do.

Regards,

Vince

That is a very nice offer

:thumb:

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Hi Unclemack,

Nice turntable the Luxman PD 350, too good to scrap.

I'm based in Nowra NSW and can arrange free shipping from Southern Cross and return by coach, Premier Motor Service.

Send it up and I will see what I can do.

Regards,

Vince

That's very kind Vince. I'll PM you in the coming days to work out how to go about this..

 

Cheers

 

M

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Good on ya, Vince. ;)

 

Stuart seems to have performed some pretty exhaustive diagnostics and pinned the problem down:

 

"It's the actual drive chip that is generating the heat and it seems to hit a point where it gets into thermal run-away and then loses the plot."

 

"Without the platter on, the problem never occurs. Maybe the bearing has more friction than normal, causing excess load on the drive IC?"

 

The only problem about that theory IMO is that UM said the platter would turn at the right speed for several hours ... if there was a "sticking" problem that would generate friction (which, yes, could indeed then cause the drive IC to over-work and get hot) ... then how come this doesn't:

  1. happen for a few hours with the platter on, and
  2. never happens with the platter off?

Stuart said he checked the DC rails - and they didn't vary. :eek:

 

From the above ... maybe (as it never happens with the platter off) there's a wear problem at the bottom of the bearing, caused by the extra weight?  Can you replace the bearing with one of yours?  Failing that, maybe a huge heatsink on the drive IC is the easy solution?

 

 

Good luck,

 

Andy

Edited by andyr
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