Dual Service

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Tinkaroo
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Re: Servicing Dual Turntables - Revised

Post by Tinkaroo » 30 Oct 2015 09:17

I also have a Dual 721 and experienced a similar speed fluctuation issue. I tried cleaning out the speed pot with some contact cleaner which helped for a while.

The problem kept re-occurring periodically,so I then ended up changing the pot out with a used one which fixed the problem.

Hopefully it is just something simple like that, and cleaning the speed pot will help.

Good luck!

pdrummer
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Re: Servicing Dual Turntables - Revised

Post by pdrummer » 30 Oct 2015 20:55

Hi I have a Dual 506 & the motor is running fast took it to a shop to get it fix they did fix it but for got to tell me the strobe light was not working so when I got home I played w/ it & did something so now it sound like it going too fast, So I took it back to the record store but they said they couldn't fix it. Some one here said there was a screw I have to play with? but my Question is how do you Check the RPM? Play a record & time it? any help would be great Thanks
Paul..

Tinkaroo
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Re: Servicing Dual Turntables - Revised

Post by Tinkaroo » 30 Oct 2015 21:06

You could time 100 revolutions in 3 minutes or use a strobe disc and an led light source. If your platter is milled with strobe markings then an led light source should be enough.

The led light would need to be powered by the house current.

tlc630
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Re: Servicing Dual Turntables - Revised

Post by tlc630 » 30 Dec 2015 18:03

In several places, most recently in this discussion, it has been stated not to adjust the idler shaft.
I have now restored 3 1019s and on each and everyone of the have found the set screw on the pulley to be inaccessible with the motor installed. Removing the motor and trying to move the pulley a tiny fraction of an inch has proved to be a losing strategy.
On the other hand, it is extremely easy to put the idler mechanism in the 16rpm position, loosen the 5.5mm nut, and turn the slotted shaft a turn or two to get proper adjustment of the idler height, and re-tighten the nut.
What is wrong with this procedure?

Hugues TR4
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Re: Servicing Dual Turntables - Revised

Post by Hugues TR4 » 30 Dec 2015 20:03

As a matter of facts, I've also been faced to the same issue, solved by the same procedure.
Only thing, you absolutely need rubber gloves to do this as it involves a lot of manipulations in very sensitive to finger prints parts.
The most important is to adjust the position of the idler wheel right in the middle of the pulley speed surface, with the pitch control knob set in the middle, at point zero.
And you can do it through the idler shaft too.
The other procedure is quite a PITA with the 1019 but much easier with the central set screw (116) on the 1219.
And it works both ways...
Cheers,

Hugh.

dualcan
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Re: Servicing Dual Turntables - Revised

Post by dualcan » 30 Dec 2015 20:31

There is nothing wrong in adjusting the stem of the idler if two things are respected.
1. You must stay in the proper area of the platter's inner running surface, which also means not to have the speed pulley too high where it could touch the platter.
2. Most of the time the counter nut is not loosened so the top end is split/broken off resulting in a poor hold for the vinyl washer.
Regards,
k

exwiso
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Re: Servicing Dual Turntables - Revised

Post by exwiso » 01 Jan 2016 04:56

Thank you for such a superb document. It has given me the confidence to do a motor service on the 1219. This and the the tone arm are two areas I haven't been game to touch. So that's one down...Any chance of of a similar treatment for the tone arm?

The motor is all back together and sweet as can be, but the thought did occur that the copper disc sitting in the bottom cup, carrying the weight of the armature, must have potential for vibration.

I am wondering if there would be any harm in slipping a piece of 0.8mm thick damping material between the disc and bottom shell? I am thinking specifically of a piece of Herbie's Audio Lab's silicone-based viscoelastic "Grungebuster" sheet.

Would raising the armature by something less that 0.8mm be problem? There looks to be room under the cover cap. Would you think it would be worth the trouble?

Spinning
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Re: Servicing Dual Turntables - Revised

Post by Spinning » 02 Jan 2016 04:59

Thanks to Klaus and everyone else involved in creating the excellent, detailed service documents. They are an immense help to my new hobby of restoring/repairing Dual turntables.

dualcan
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Re: Servicing Dual Turntables - Revised

Post by dualcan » 02 Jan 2016 06:06

Hi Exwiso,
These motors are combined induction with a synchronous section added. The synchronous section is the magnet ring on the rotor and its partner section on the stator. By raising the rotor, you are misaligning these two sections and their functionality (speed correction via the mains/AC frequency) may be diminished. Can you get away with 0.8, I don't know. Normally just flipping the copper disc is enough to get the motor running properly.
One thing is a must though. The rotor has to sit solidly on the bottom support and can not vary vertically since any variation would change speed/pitch due to the pulley being sloped.
Regards,
k

exwiso
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Re: Servicing Dual Turntables - Revised

Post by exwiso » 02 Jan 2016 07:43

Ah so...Thank you Klaus. If it ain't broke...

ooba tooba
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Re: Servicing Dual Turntables - Revised

Post by ooba tooba » 26 Jan 2016 20:28

I would also like to thank all involved in this. I found this while starting threads on audiokarma regarding 1019 service. Can I use white lithium grease on the cam when relubing? And should I use a thick oil, or grease for where all the metal levers touch? Also was wondering if it was necessary to disassemble the motor bearing to clean and relube.

Spinning
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Re: Servicing Dual Turntables - Revised

Post by Spinning » 26 Jan 2016 22:21

Managed to find an English vers. Service Manual for Dual 1220/1222 turntables. Will scan and upload for posting shortly.

tplate
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Re: Servicing Dual Turntables - Revised

Post by tplate » 16 Feb 2016 02:55

I have a Dual 1218 turntable that I purchased in the early 70s while stationed in Germany that worked great until it was put into storage about 10 years ago. Finally have a place to put the components back to use and listen to the old albums from that era, however when unpacking and connecting all the pieces the turntable doesn't seem to power up. Not sure where to look first to trouble shoot. Any suggestions?

dualcan
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Re: Servicing Dual Turntables - Revised

Post by dualcan » 16 Feb 2016 23:01

Hi,
The problem is always dried lubes and specifically the shaft 257 which is stuck inside 254 and mainly 252.Use service manual 1218 from Library/Dual/1218 above. This lever (252) must be free to move because it controls the power switch movement. I have a restoration illustration on my webpage (blue ball to the left)for a 1216 which is very similar to the 1218.
Regards,
k

audiopile
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Re: Servicing Dual Turntables - Revised

Post by audiopile » 17 Feb 2016 00:23

I haven't stripped ,cleaned and re-lubed a Dual in probably 20 years - but even back then - half way measures were pretty much a waste of time -add 20 years of hardening and it just seems that nowadays it doesn't pay to get into a (Dual,Garrard,P-E,Benjamin Miracord ,BSR or BIC) unless you anticipate a thorough clean and relube. The good news is that if you do this and actually routinely enjoy the machine - it will be decades before you need to do it again.But buying a unit that has been sitting un-used for 10 or more years and expecting it to work properly isn't terribly likely.

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