Dual 1218 grinds to a halt on auto-start, auto-return

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HarryV
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Dual 1218 grinds to a halt on auto-start, auto-return

Post by HarryV » 25 May 2019 08:27

Hi, That's the problem in a nutshell, the platter gets slower and slower when the tonearm is returning and finally stops needing some manual assistance to complete the actions, starting is not quite so bad but certainly not good. The machine has been de-greased and lubed, the idler and its mechanism is good, the platter spins freely with motor off, the motor has been serviced and spins perfectly as far as I can tell visually with the platter off, the cam has been removed and de-greased and had a little lithium grease applied sparingly also. It all worked a short while ago but has been in storage a few months. I'm suspecting the steuerpimpel which looks ok but who knows... It is possibly slightly tilted.
Any other ideas on this one please?
Also can anyone confirm if the pimpel should be a really tight fit so that it doesn't rotate on its shaft, or should it rotate to some degree. Thanks.

DSJR
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Re: Dual 1218 grinds to a halt on auto-start, auto-return

Post by DSJR » 25 May 2019 12:33

Have you downloaded and digested the service manual from the library here?

Grease - Did you *clean all the old stuff off completely* before SPARINGLY adding more? If not, a stripdown is needed and fresh Alvania can be got from mrow2 Don here, as originally used, together with an excellent simple service sheet and pimpels etc.. I know Superlube is reportedly a good long lasting alternative, but the original has lasted forty odd years (nearly 50 in a 1218) and a fresh application will see us out... Mixing greases on these decks is not a good idea and I've personally see the horrid mayonnaise that can result when doing this - ugh!!

Pimpels should be a firm fit on their mounting stud which is often spring mounted. If said replacement pimpel is too deep, preventing its possible sprung mount from working (depends on the model I believe), then this could well bind up the mechanism (main lever operation) and may end up damaging the alignment of the stud that runs in the cam and even the cam itself...

If nothing's binding, then the idler or the inner driving face of the platter may need a thorough de-greasing and the motor pulley checked for tightness on the rotor spindle. There should be healthy torque preventing the platter from being stopped if you try to stop a running platter and slippage here is usually the issue.

HarryV
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Re: Dual 1218 grinds to a halt on auto-start, auto-return

Post by HarryV » 25 May 2019 13:25

Thanks for the reply... Yes, I have referred to the service manual and several internet posts but haven't seen anything describing my particular problem. I'm pretty sure all the cleaning and re-lubing I have done is satisfactory and no more is required.
I put a new (DIY, temporary) steuerpimpel on and though tonearm movement was hesitant on first try it seems to be completing the auto-start, stop functions without any manual assistance now.
...
I'm not totally happy with the idler wheel, I had to sand it ever so slightly to get a flat spot out and I also de-greased the mech as it was very stiff. Now I notice the wheel doesn't press against the motor spindle when 'start' lever is engaged with the platter off (at 33rpm), it moves towards it but then sort of lags back with the edge of the wheel a mm. or so away from the spindle. The contact with the platter when it is present must push it onto the spindle I imagine as the platter does spin, but I wonder if the behaviour I have described is correct. Any comments appreciated.

Alec124c41
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Re: Dual 1218 grinds to a halt on auto-start, auto-return

Post by Alec124c41 » 25 May 2019 14:14

The bearing of the arm that the idler is on needs cleaning and re-lubing.
Then check that the spring is not too stretched to make that contact.

Cheers,
Alec

HarryV
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Re: Dual 1218 grinds to a halt on auto-start, auto-return

Post by HarryV » 25 May 2019 17:36

Thanks Alec, I take it you are saying that the idler wheel should make contact with the motor spindle when starting the tt with the platter off. In that case I will rig up a stronger spring and see if that improves things.

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Re: Dual 1218 grinds to a halt on auto-start, auto-return

Post by mrow2 » 25 May 2019 18:13

The system is designed to work when the platter is in place, so that the idler is drawn in (and slightly pushed [or squeezed] against the platter). I.e., Idler should automatically come to the pulley (not spindle) and to the platter drum with good contact force. Platter drum can be cleaned (maybe even gently use 400 grit paper) and wiped with isopropyl, no fingerprints allowed anywhere. Idler should be smooth. Follow Alec as re: the idler bracket, these get dirty and don't move around like they should. This, along with the dried grease here and there, might cause the symptom.

HarryV
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Re: Dual 1218 grinds to a halt on auto-start, auto-return

Post by HarryV » 26 May 2019 10:15

Thanks for the clarification, a stronger spring seems to have improved things and the platter seems steadier and stronger when going through the auto functions; the idler is still not getting to contact the pulley without the platter on at 33 rpm so I will do a little more tinkering.( I am pretty sure there is no need to clean the idler assembly as I had it in bits not long ago and got it moving really freely.)

DSJR
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Re: Dual 1218 grinds to a halt on auto-start, auto-return

Post by DSJR » 26 May 2019 10:26

Dual idlers don't have a flat driving face, as it's slightly radiused. take care when 'sanding' the edge down. I have to say the spring here shouldn't stretch over the years - all mine are original. there probably won't be contact at 33 with platter off - quite normal.

Remember the speed adjustment parts do involve a few 'pivots' and these must be free to pivot correctly for the 'physics' to work on engaging the idler in play mode. I still haven't looked at the 1009SK2 I have here, where the mech seems free enough but the speed change mechanism is all but seized solid.

HarryV
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Re: Dual 1218 grinds to a halt on auto-start, auto-return

Post by HarryV » 26 May 2019 14:22

Your points noted DSJR. My original spring doesn't appear stretched or stressed I must say though it does seem a bit too long for the job, and quite a weak gauge, I wondered if it was the correct one but from pics I found on the net it looks like it is. I do like these machines but it can be frustrating to get everything happily working together to put it mildly!!

mrow2
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Re: Dual 1218 grinds to a halt on auto-start, auto-return

Post by mrow2 » 26 May 2019 19:50

The older idler doesn't have quite the same gripping ability as a wheel with fresh rubber. Still, it should work. DSJR mentions the slight radius which is needed on the idler. Since the pulley is tapered, the radius is very important, and should be just right. If too much material has been taken off the idler, it may have difficulty with the necessary "reach" distance to the platter when engaged, but I suspect that would be pretty noticeable.

Hopefully you sanded and cleaned the platter drum and have no fingerprints on it anywhere? I presume you do have a small amount of a slick lube on the idler bracket shaft and maybe the wheel bearing (a tiny fraction of a single drop, applied with a toothpick)?

HarryV
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Re: Dual 1218 grinds to a halt on auto-start, auto-return

Post by HarryV » 26 May 2019 22:25

Seems to be OK now, I have put a slightly stronger Spring on and cleaned the wheel and platter, (though I don't think they were playing any part in the problem), thanks to all for advice given.

mrow2
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Re: Dual 1218 grinds to a halt on auto-start, auto-return

Post by mrow2 » 26 May 2019 22:48

Cleaning the inside of the platter (i.e., removing old and new fingerprints) is very important with some of these models. 1019 is another one which presents a challenge. Fingers contain oil, it easily smears the platter drum and reduces traction. Freshening the surface with a 400 grit paper (maybe at a diagonal to the idler) dresses the platter; the isopropyl cloth cleans away the dust and it will remain pristine for a long time once it is set. At any rate it's good to have the parts cleaned up.

Hugues TR4
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Re: Dual 1218 grinds to a halt on auto-start, auto-return

Post by Hugues TR4 » 27 May 2019 21:13

Have you removed, cleaned and properly re-lubed (Klaus advises Renotac or chain saw oil) the 257 "grooved shaft" which holds the main switch arm 250?
It very often gets seized by the old grease and a good cleaning makes a lot of difference. I even polish it before putting it back to its place.
My penny…

Cheers,

Hugh.

HarryV
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Re: Dual 1218 grinds to a halt on auto-start, auto-return

Post by HarryV » 27 May 2019 22:00

Yes Hugh, had to do that as things were really stuck there, thanks for raising it though.

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