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Calibrate dual tonearm

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Calibrate dual tonearm

Postby grabread » 08 Jan 2017 13:12

Does anyone know how to calibrate the dual tonearm cs503-1 type? I'm not referring to the balancing and basic setting but the proper setting up of the mechanism itself.
I think a previous owner has partly stripped the arm and I'm wondering if there is a proper way to calibrate the mechanism itself.

Many thanks.
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Re: Calibrate dual tonearm

Postby DSJR » 08 Jan 2017 16:49

Apart from making sure everything is in place, clean and only lightly lubed where necessary, I can't think of anything else to do, as the mechs weren't so fine that everything needed adjustment. Have a look at the service manual too for hints and if you can, watch the mechanism working if anything is sticking or not doing what it should be doing... The 503 appears to be auto-stop only, so make sure there's a ball bearing running in the tonearm link from arm to pawls at the main spindle end (under the inner platter). This offers a very low friction link and there's noticeable drag if the ball has gone awol. Setting the tonearm bearings has been discussed many times here - balance the arm out with everything set to zero and first make sure the arm stays generally where it's placed. Place a stamp on the headshell. The arm should move smoothly downwards. Apply a touch of bias correction (antiskate) and the arm should move smoothly back to rest position. ALL Dual tonearms should have good notch-free bearings, even the humblest ones and this is no exception. If the arm is ok, then all you need to check now are the running speeds, which are finely adjustable if you have a strobe to check them with.

The main weakness in these Duals (there were *and still are* others sharing this generic chassis) was the cartridge fitted. I'm sure that something like an AT95E would be a useful upgrade, now the Ortofon OM series are so expensive (if you can fine an OM10 fairly cheaply, I'd consider it too).

I'd also suggest running the deck with lid removed or at least down and please take huge care in siting for best bass reproduction.
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Re: Calibrate dual tonearm

Postby grabread » 08 Jan 2017 22:34

Thanks for the reply, I am interested in how the downforce adjustment mechanism works and is able to be calibrated, ie how does the adjustment wheel actually produce the downforce. The adjustment wheel was loose and going round and round, I have tightened the screw and it now adjusts but I'm sure the down force is not correct.

many thanks for any replies
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Re: Calibrate dual tonearm

Postby DSJR » 09 Jan 2017 10:59

Ah ok, got it now :)

Look on Dualcan's website for service details regarding Dual arms and their bearing settings. Broadly speaking, the vertical pivots are set the same from model to model I think and with minor variations. Tracking force is applied by a coil spring fixed at the inner pivot end and 'wound up' slightly at the outer edge which is attached to the calibration dial. Build it up properly and the spring gives very accurate downforce. I dare not talk you through it as others here are more articulate and Dualcan Klaus' site should have most if not all you need to set and adjust the arm bearings - the screw at the dial side usually has a 'backwards' thread I recall and you fix this side first - with the other bearing pivot set slightly loose before gently setting it for minimal play and minimal friction. Take care the needle pivots are centred in their races before carefully setting

Hope this helps.
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Re: Calibrate dual tonearm

Postby dualcan » 09 Jan 2017 18:41

Hi,
I just had a request for the same set up and alignment for a 1219 arm. The following outline/procedure is pretty well identical for all gimbal mounted tone arms including this arm. Some of the later Dual models will have a spring mounted horizontal (bottom) bearings, so there is no horizontal slack adjustment but otherwise very similar.
Here is my reply with reference to a 1219 parts:

The gimbal must have a very small amount of play.
The first step is to tighten 53 (left hand thread) onto 49 through 56. Make sure to align the zero on 49 with the arrow on the arm's bearing block. You might need to rotate and adjust 49 several times until the zero and the arrow stop precisely in line with the arm in a balanced (water level)incline. Once this alignment is correct, finger tighten 53.
Next, introduce 57 into the arm's bearing block --slooowly- to make sure you hit the centre of the bearing-not the sides--. Turn until 57 touches the bearing bottom (no play). Now slip on 58 and bring near but not tight on 57. Back off 57 from bearing block so that you just barely feel play in the bearing- about a 1/4 turn maybe less. Next snug tighten 58 onto 57 but hold position of 57. This must be carried out several times, until the play is just perceptible.
Horizontal bearing part 41 and 52 will be set the same way as 57 and 58.
Once these two are set, and the dial (49) is properly zeroed as explained above, you can make the arm's bearing test with a stamp and 0.5 p on the anti skate dial.
Here is the procedure to check both planes:

Vertical test:
1. Set arm for zero tracking force and zero antiskate force.
2. Balance arm perfectly (perhaps without stylus for safety) .
3. * Place arm between platter and rest post, so it can descent. *
4. Drop a stamp on the head (over cartridge).
Arm must descent all the way for the 1200 series, most of the way for 1000 series with tk 12 headshells and at least lower somewhat for 1009, the lower, the better obviously...
If arm moves without hesitation then vertical bearings are ok.
*Note: for the 1219/1229/1229Q, there is a rubber bridge mounted left of and into the rest post, pivoting on a chrome shaft. This rubber bridge can be shifted/removed to enable a proper vertical test.

Horizontal test:
1. Balance arm as before (no stylus-no stamp...)
2. Apply 0.5 anti-skate on any side of the Anti Skate dial under the tone arm.
3. Bring arm towards center of record.
4. Let arm go.
Arm must return all the way back to rest post without hesitation.
If arm moves without hesitation, then horizontal bearings are ok.
That's it for the test.
Klaus Adlhoch, fmr. Assistant Service Manager,
Noresco -N.Q.I.-Dual of Canada,
Area of expertise: Tech Training and Consumer Service P.R.
Associated with Dual till Thompson era.
Favorite Duals: TG 12a, 1009, 721.
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Re: Calibrate dual tonearm

Postby grabread » 09 Jan 2017 20:14

Thanks Dualcan but it is the later? side wheel type that I am having problems with.
I think there is a spring in there somewhere (perhaps broken?) as I can hear a noise when the dial revolves.

Many thanks
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Re: Calibrate dual tonearm

Postby dualcan » 09 Jan 2017 20:53

Hi,
The 503 has the same basic arm bearing setup as the older 1219, but the tracking dial wheel here, is in two parts. The actual spring (83) is in the tonearm bearing block/housing and the actual dial (81) is external. Apart from this variance, the procedure is still the same. First set up the tracking dial side (82/81,80 onto 54) and subsequently into the spring (83). Make sure the zero and the indicator line up with balanced arm then continue as I outlined for the 1219 substituting the related part of the 503 for the 1219 nrs. The final arm test stays the same for bearing friction.
Regards,
k
Klaus Adlhoch, fmr. Assistant Service Manager,
Noresco -N.Q.I.-Dual of Canada,
Area of expertise: Tech Training and Consumer Service P.R.
Associated with Dual till Thompson era.
Favorite Duals: TG 12a, 1009, 721.
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Re: Calibrate dual tonearm

Postby grabread » 09 Jan 2017 21:29

Thanks dualcan, does it matter how tight the centre screw for dial 81 is set?
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Re: Calibrate dual tonearm

Postby dualcan » 10 Jan 2017 01:08

Hi,
This is a similar set up from a 620.
Here I removed the screw, dial and bowed washer:
DSC00084.JPG

Next I located the dial without washer and screw to make sure the dial sits properly and engages the cage. Make sure the dial stops at zero in line with the marker line:
DSC00086.JPG

Now replace the bowed washer and screw and tighten with reasonable force till it seats. This bolt is normal right hand thread.:
DSC00088.JPG

The arm's bearing play is adjusted by pin 51/52 if the play is too tight or too loose.
Regards,
k
Klaus Adlhoch, fmr. Assistant Service Manager,
Noresco -N.Q.I.-Dual of Canada,
Area of expertise: Tech Training and Consumer Service P.R.
Associated with Dual till Thompson era.
Favorite Duals: TG 12a, 1009, 721.
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Re: Calibrate dual tonearm

Postby grabread » 10 Jan 2017 09:18

Great reply, and thanks for the pictures. I have got it back together now and I have ordered a stylus force gauge just to double check all is well.

Many thanks
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Re: Calibrate dual tonearm

Postby DSJR » 10 Jan 2017 12:31

Regarding mechanical stylus force gauges.. Dual's tonearm-fitted gauges are pretty darmed good to be honest, but if you want a reference, have a look below for my experiences...

I'm spoiled because I have an extremely accurate Transcriptors/Michell stylus balance using hand trimmed weights to pre set the balance to within 1/20th gramme as a reference.

The little Ortofon balance is fine here, consistent and inexpensive. I never got on with a Shure balance I had because if I set using one of the scales, the other was way out and vice versa - maybe mine was faulty somehow?

I must give a shout here to this balance once used by AR in the XB1 at least, it's down near the bottom of the page -

http://www.esotericsound.com/access.htm

I found it dead accurate to 1/4g and consistent. The weights are positively located and I haven't a clue what happened to mine, as I used it a lot in my early days setting up turntables :(
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Re: Calibrate dual tonearm

Postby grabread » 10 Jan 2017 21:37

Well, got the stylus force gauge today and as suspected the arm is well off. when it reads 1g on the wheel it is about .8gm but when you go to 2g on the wheel the spring makes a noise and pressure drops to .6g
Something not right with the spring housing or spring? I'm going to have to strip the arm down
BTW are any parts available these days?

Many thanks.
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Re: Calibrate dual tonearm

Postby grabread » 10 Jan 2017 23:11

Update, stripped the arm and found that the spring was not located properly in the spring housing and was slipping round. All now reassembled and set up as per Dualcans postage stamp method.
Dial now accurate to better than 0.10 gram.

Many thanks to all contributors.
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Re: Calibrate dual tonearm

Postby Minstrel SE » 14 Jan 2017 08:28

Great because I can say that the 505 arm is amazingly accurate when compared to a digital tracking force scale.

It just gave me confidence that Dual really knew about design parameters whether it be the 505, the 400 series or the 503 just to give a few examples.

Previously there was sometimes a tendency to wonder how good this tube of aluminium and dials are :)

It certainly does the job and Ive never had a record skip once even on some real ski jump pressings.

Best wishes with it
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Re: Calibrate dual tonearm

Postby dualcan » 14 Jan 2017 17:15

Hi,
The accuracy of the tacking wheel is simply a continued piece of precision which was started in the Black Forest way before turntables were even contemplated. It is the area in which the famous clock-making industries, most of them cottage enterprises, thrived (an is still present). That was the beginning of the fame for the Steidinger clan as well.
As far as the Steidinger/Dual tracking dial, from 1963 and up, here are a few examples of that accuracy. All arms are properly balanced and set for 1p tracking.

1009:
1009 TF.JPG


1219 with instrument double check, The suspended scale was the preferred tool from PE, the correx from Dual:
1219 TF  scale  verif.JPG


1229:
1229 TF.JPG


522:
522 TF .JPG



As can be seen by this Ortofon ad, the correx scale which is being used is a precision instrument for lab use:
ortofon correx.jpg


An updated correx scale can still be had today if you have any doubt about these old Dual's tracking accuracy:
https://www.hahn-kolb.de/CORREX-spring-balance-spherical-probe-MB/44101030.sku/en/US/EUR/
Regards,
k
Klaus Adlhoch, fmr. Assistant Service Manager,
Noresco -N.Q.I.-Dual of Canada,
Area of expertise: Tech Training and Consumer Service P.R.
Associated with Dual till Thompson era.
Favorite Duals: TG 12a, 1009, 721.
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