Dual 701 Peculiar arm movement.

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Analogd
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Dual 701 Peculiar arm movement.

Post by Analogd » 15 Apr 2019 11:20

I'm after a bit of advice from you Dual gurus please.
I have just bought a nice Dual 701 in quite remarkable original condition.
I have replaced the stierpimple ( spelling ? ) and checked that all the auto mechanism is free and appears to be operating correctly.
However when the arm returns at the end of play it travels smoothly to the rest but just before it is lowered onto the rest it makes a sudden movement back towards the platter by about 20mm and usually then rests on the rest extension instead of the correct spot. At start up the arm moves back to the correct start position on the rest and performs correctly.
I cant for the life of me figure out why it is doing this.
Any advice would be gratefully received.
Cheers. :D

DSJR
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Re: Dual 701 Peculiar arm movement.

Post by DSJR » 15 Apr 2019 15:09

Pimpel's probably the wrong one, unless you've 'adjusted' the main lever (see fig 21 in service manual)! The pimpel shouldn't/mustn't be so deep it prevents its sprung mounting stud from working properly. The main lever adjustment (only there on some other Duals such as the 1229) shouldn't need touching unless the cam's replaced.

At end of play, the main lever takes the arm back, is then held in place by the cam follower #115 on the cam, which holds the main lever in the 'outer' cam groove rather than sweeping in to the record index point and onwards. The main lever then tilts back (articulated on the 701 and family) to lower the arm and only at the end and supposedly with the pimpel now disconnected, is the main lever rapidly returned to 'neutral' position in 'stop' mode. If the pimpel is too deep, it won't fully disconnect from the main lever at the end of the cycle quickly enough and the arm will swing back in. I'm assuming everything else hasn't been disturbed - and watch it if you remove the cam, as it's bearing 'stud' also plays pivot on other parts too I remember and these must be aligned properly before replacing the C clip that holds it all in place (I'm not in the habit today of trying to fix what ain't broken, so while my deck is working, I leave it well alone ;)).

Hope this kind of helps. 601's, 701's and it's descendants, are VERY fussy creatures and in the case of the 701, very delicate with it. PLEASE read as much as you can and take HUGE care with now unobtainium parts. In fairness, with correct parts and carefully set up, they'll run for decades reliably, it's just now after forty five or more years that certain 'rubbery' parts need replacing and greases cleaning off and replenishing sparingly.

P.S. What's a typical 'service life' of audio gear? Five years (cassette decks and well thrashed VHS recorders?), ten years perhaps? These mechanical devices, even sh**ty old BSR auto-changers, let alone top Duals, PE and Elac decks, are fifty or even sixty years old and still giving pleasure after a good fettling. I thought my own 701 was old when I bought it in the late 80's (late series 1, so '73 or '74 manufacture?) and here it is, getting intermittent use thirty years later :D

mrow2
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Re: Dual 701 Peculiar arm movement.

Post by mrow2 » 16 Apr 2019 00:38

In my mind's eye, something which might cause this (on a TT as sensitive as 701) is a little clump of grease on the main lever paddle which sticks to the pimpel as it pulls away. Also be certain the flat "pad" of the steuerpimpel is in fact flat upon the main lever, symmetrical no matter which way it turns on the 2mm post. If not in this area then it is something else which is touching the linkage to the tonearm prior to settling upon the rest.

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