Tips on servicing Dul 621

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Timfromfmass
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Joined: 28 Nov 2018 06:28

Tips on servicing Dul 621

Post by Timfromfmass » 11 Jan 2019 00:14

Hi all. I got a 621 a couple of months ago and have been enjoying it quite a bit. It’s in great cosmetic shape. The speed is consistent I just had to adjust the shift a bit to get the timing right. The auto start doesn’t work, which has been fine with me, but now it doesn’t sense when the record is done. What it used to do was sense when it was at and end and then lift but not return the tone arm. I’m new to turntables but not to electronics and I’m reasonably handy. I’ve doenloded the service manual but figured I would ask some questions here to before I get started.

I know to get the auto start to work I need to replace the steuerpimpel, will this also fix the issue I’m having when the record is done playing or is that something else? Does anyone have a good reliable preferred source for a steuerpimpel shipping to the US?

That is the main reason I want to open this guy up, but I’ll probbaly grease the points listed in the service manual as well. Is there anything else you experienced dual owners would recommend I look at while in there? Things that commonly go wrong down the road or that may be not functioning correctly without my even knowing it?

Lastly how hard is it to replace the rca cables supplied. I’m not one that believes in high end cables, but I would just like to get something newer that has cleaner connectors unless this is a major PITA task

Thanks in advance for the Help

mrow2
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Re: Tips on servicing Dul 621

Post by mrow2 » 11 Jan 2019 07:44

I will send you a P.M. These are pretty basic questions; the new steuerpimpel will usually correct the auto start and return to rest issues. We have lots of discussion on RCA cables; you can just search the topic and read threads for a half hour or longer and you'll be fairly well informed on what to look for and what might not be a good technical match. Cables are valued for their ability to isolate hum and also for capacitance ratings. There are some mistakes to be made. A common one is to use cables which look ok but were really intended for Hi-Fi gear like tape players and CD players etc, those are considered line-level sources whereas a phono circuit is amplified by a second stage in the main amplifier (the pre-amp circuits), and many line-level cables are not intended to do that. -- Don

Tinkaroo
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Re: Tips on servicing Dul 621

Post by Tinkaroo » 11 Jan 2019 13:31

A number of years ago I had my 621 serviced by Klaus Z. At the time besides the usual service he replaced both the RCA plugs on the end of the original wires.

The plugs themselves where the wire attaches often get damaged over the years from the amp or receiver, getting jammed against a wall or cabinet, or just general bending, pulling, yanking on the wire to remove the plug, etc.. You don't have to replace the wire and plug, just the plug as Klaus did on mine. The wire Dual used is very good quality.

Klaus did a good job since eight years later it hasn't missed a beat.

DSJR
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Re: Tips on servicing Dul 621

Post by DSJR » 11 Jan 2019 13:49

A shame in a way that some of the suitable cables available in the Uk may not be available in the US - and vice versa. For European people, I find Van Damme do a perfect range of not-silly-money and quite flexible cables (Tour Grade XKE) and these can be got on eBay with one end pre terminated, usually with nice Neutrik RCA phono plugs. the other end is often tinned ready to solder on (usually intended for Technics decks thrashed around in club or DJ use, although 1970's top line models now suffer internal cable fractures too). I also use twin core mic cables, using the two cores for signal hot and return and connecting the outer cable screens to the amp end of the cables (inside the RCA plugs). These involve heatshrink at the deck end and careful soldering skills, so maybe not for people not confident with a soldering iron.

The wires Dual used don't look posh at all and because the uninitiated often listen with their eyes, these cables can be ditched purely on looks - takes one to know one and I did this 'automatically' with my 701 cables without following the thoughts through!

A negative in replacing Dual's cables is that the novel cable clamping arrangements in most of the 12** onwards plinths goes straight out of the window. It's vital that these now loose wires aren't pulled hard or snagged, as at best, the suspension is bypassed and at worst, connections broken.

Timfromfmass
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Re: Tips on servicing Dul 621

Post by Timfromfmass » 11 Jan 2019 15:14

Alright if the cables originally supplied are that perfect I won’t bother wigh that replacement. I’ll just give the rca terminations a more thorough cleaning.

Any other problem areas I should check on while I have it opened?

raaawkstar
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Re: Tips on servicing Dul 621

Post by raaawkstar » 13 Jan 2019 06:09

I own the same machine, just got it and it's in really amazing shape with a few issues I'm working to resolve but the "pimple" took 2 minutes, I cut off a small end of a Paper Mate pen refill and it seemed to fix the problem, I may cut another a tad longer...hard to tell being I have to solder two wires so I can only test by turning the yellow gear, the black plastic piece is rubbing the homemade "pimple" and it seems to engage the push and pulls for lack of a better word! I too had planned on replacing the cables on mine but will know pass. I have a 506 that someone put some Monster Cable type RCA's which I think I'll redo when I decide to fix it up for sale or as a backup.

DSJR
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Re: Tips on servicing Dul 621

Post by DSJR » 13 Jan 2019 18:29

NOOOOOOOOO!!!!

A short length of pen refill is a total BODGE and won't work quite the same - I've been there and am still using this on the 701, which I don't want to disturb any more after the motor shenanigans I suffered a couple of years ago! For one thing, the length of the pimpel needs to be specific, especially if the pin it's mounted on is sprung as the 601 and 701 is. Secondly, Dual worked out a kind of relationship between friction on the main lever 'paddle' and the added Alvania grease. This is a 'bodge' enough, but it works for twenty or thirty years and that's enough really!

My 701 arm moves back and forth ok with the 'pen refill pimpel' but it's not especially smooth nor as 'slick' as the real thing, especially returning the arm to the rest and indexing 7" singles/ep's.

I appreciate the loaded-plastic main levers that Dual moved to may well offer better 'grip' of the pimpel, but don't spoil it - please?

Back to external audio cables. The supplied are fine for many MM cartridges as used in these decks and the internal copper seems to hold up well with age, but the moulded-on phono plugs do break. I'd look at the grounding first before replacing the cables, isolating the deck grounding from the cartridge cables at the terminal-muting assembly for a start - discussed here many times... I use low output MC cartridges sometimes in my Duals and this is where a modern well-screened flexible mic or not thick guitar cable from a trusted maker comes in - in my opinion and experience.

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