Big problem with 1219/1229 sleds losing connection in one channel or both

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PaulKehayas
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Big problem with 1219/1229 sleds losing connection in one channel or both

Post by PaulKehayas » 19 May 2019 13:32

Ok.
The connections have been cleaned on the little board. The sleds are old stock TKs. They also have been cleaned as well but it seems that on at least 3 turntables I know of, there are problems regarding these things.
I have stopped recommending Duals to my pals and am weary of restoring them for others because of this one problem.
Why and what to do about it because I dread these phone calls that say "the left channel has cut out and I have tried the sled reinstall trick you recommend."
I am getting more than a little fed up with this problem as it happens on my own 1219 that is clean as a whistle!!
What gives and what isn't making the connection?
BTW these are all spring loaded pins with the exception of one sled.
I am now counting at least 5 failures between these sleds on 3 different turntables.
Most of these recurring. Some permenant failures where nothing can be done to kick them into working.
help!

b+v8an
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Re: Big problem with 1219/1229 sleds losing connection in one channel or both

Post by b+v8an » 19 May 2019 15:52

Sometimes the wires are broken and it is not visible at all.I put a meter on them and wiggle them a little. It is very obvious when you find a bad one and a pita to fix. Those little springs love to run away and hide.

tlc630
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Re: Big problem with 1219/1229 sleds losing connection in one channel or both

Post by tlc630 » 19 May 2019 16:25

Which type of sled are you having problems with? A couple of different ones fit in the 1219/1229 line.

The following thread may help out - viewtopic.php?t=90949&sid=583103929a0c4 ... bd#p760942

mrow2
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Re: Big problem with 1219/1229 sleds losing connection in one channel or both

Post by mrow2 » 19 May 2019 16:57

Hi Paul Been a long time but don't you have my PDF? There's a good section on this in it. Just about the most common problem; I talk about all of it in the section. If the version is too old, contact me. Don

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Re: Big problem with 1219/1229 sleds losing connection in one channel or both

Post by ubaldojhp » 19 May 2019 22:22

Sometimes the problem is inside the turntable. There is a mechanism that starts/stop the sound beside the connections (rca/tonearm wires). In my Dual 1225 happens that. There are two small levers touching the yellow wheel that activate the sound

musicmn
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Re: Big problem with 1219/1229 sleds losing connection in one channel or both

Post by musicmn » 20 May 2019 01:30

Hi Paul, this might not be the answer you are looking for but one thing you could do is to install new 33 awg tonearm wires with the tags already mounted to them in the tonearm. You could eliminate the small circuit board from the tonearm and run the new wire from the back of the cartridge pins right to the mute switch. You can still use the dual sleds but unfortunately this will make it difficult to change cartridges. But if you have a customer that never changes cartridges only the stylus then it's no issue. I did this for a customer with a 1019 that had this dropped channel issue even with a new aftermarket sled. I just explained to him that he will need to keep the same cartridge on the sled and he had no problem with that. All he wanted was to just be able to use the turntable with no issues. I hope this helps.

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Re: Big problem with 1219/1229 sleds losing connection in one channel or both

Post by mrow2 » 20 May 2019 06:56

That method of direct-wiring the cartridge is not so great if one would like to maintain re-sale value of the turntable. The direct-wiring method and loss of simple cartridge swapping would discourage most buyers. The Dual system, while I agree that it can be frustrating, is able to be maintained in a reliable condition without too much effort, once the problems are resolved.

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Re: Big problem with 1219/1229 sleds losing connection in one channel or both

Post by zacrobmer » 20 May 2019 09:10

I was fiddling with my project 1219 this weekend and it did not have any right side audio. I checked continuity and everything was fine down to the mute switch.

However the mute switch contacts were almost black with oxidation/filth. I cleaned what I could reach with contact cleaner on a cotton swab, and then ran a piece of coffee filter wet with cleaner between the switch contacts a few times, followed up with a few wipes with a dry filter.

This cleared up the dropped audio channel for me.

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Re: Big problem with 1219/1229 sleds losing connection in one channel or both

Post by T68 » 20 May 2019 11:57

Re cleaning the mute switch: yes it's an important thing to check on these old Duals. Just be careful while cleaning them.
I did this on my 601 to try to adress loud speaker pops when turntable cycled. Well I ended up loosing audio on one channel instead :-)! I had bent one of the springy fingers out of spec while doing the cleaning.
Was a bit tricky getting it working again.

...and the speaker noise was still there until I changed a capacitor.

PaulKehayas
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Re: Big problem with 1219/1229 sleds losing connection in one channel or both

Post by PaulKehayas » 20 May 2019 16:18

Thanks all!
Much food for thought here and I am grateful for this community!
Will do a little work over the next week and report back.

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Re: Big problem with 1219/1229 sleds losing connection in one channel or both

Post by DSJR » 20 May 2019 16:51

The later TK carriers, as I'm sure 'we' all know, have sprung 'tubes' as terminals and the very tips can oxidise if you're unlucky (happened on one or two of mine, but certainly not all). I was able to gently buff them with a file and, as long as the 'spring' action was ok, it restored functionality completely. The arliest bent-copper tag TK carriers need more careful alignment and setting.

Make sure the terminals in the headshell are pushed up fully into place to ensure proper contact - just a thought.

I agree on the muting/cam lock 'fingers.' In 'play' mode, there should be around 1mm? clearance and only when cycling, should the long and shorter fingers short together. Contamination here usually means noises through the speakers when cycling.

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Re: Big problem with 1219/1229 sleds losing connection in one channel or both

Post by ubaldojhp » 20 May 2019 21:12

I have solved the problem this afternoon removing the RCA faston connections and soldering the wires directly to the terminals

PaulKehayas
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Re: Big problem with 1219/1229 sleds losing connection in one channel or both

Post by PaulKehayas » 01 Oct 2019 17:52

Reviving this thread because two cleaned and serviced (by me) 1219 and and 1229 both have connection issues.
I am wondering how to make certain that cleaned contacts are actually making contact.
This whole thing has soured me on Duals.
I need help

mrow2
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Re: Big problem with 1219/1229 sleds losing connection in one channel or both

Post by mrow2 » 01 Oct 2019 18:36

It is not such a terrible problem, but it does require some patience. The don't-do's are: no sanding anywhere, contacts or skids, whatever, except maybe with a 600 grit on the wires and the crimp surfaces only. Don't re-crimp the tiny crimps without first removing them by carefully them open first, and then cleaning and adding new wire or freshly stripped wire. The silver contacts on the little headshell board are the easiest: clean using one method or another, then dab with isopropyl. Once someone has scratched them carelessly with sandpaper (Don't do that!), the damage cannot be undone, and they become a little more of an issue. They are silver-plated, and silver simply requires some maintenance.

The carriers, with their sled-type or sprung contacts need the same treatments. Re-crimping without proper disassembly/cleaning probably just delays the inevitable. If good at soldering, the pin connectors can be soldered to the tiny wires. Put the shrink-tube piece on first, and keep it away from the heat until it's in place. Neatness counts. It's pretty delicate work; these little parts are hard to work with. Then, all the rest of the signal tracing of course. But if that's been properly done in the past, mute is clean, RCAs are clean, wires are good, then the issues are still generally in the cartridge holder. Once done properly it should probably last with just basic care. 40 years of tarnish is just too much for good reliable connections, without subsequent service. If you wish to use some new computer-board pin connectors from an electronics store, that gives you a little bit of an edge on connectivity. They might need a little pin-fit modification and length reduction, but I've seen them work. Use shrink-tubes for the wire-to-pin-connector portions.

The information above regarding mute-switch service is excellent; the contacts do need to be kept clean in the section where contact is made. They probably needn't look perfect as long as the connectivity is good.

The older-style sleds are ok, but the sled skis must be frequently re-positioned because they have almost no tensile strength. Use needle-nose for that, practice makes perfect. The spring-tube connectors are better, but there's still basic cleaning and pin clip connector maintenance to be done.

Is it a good system? Probably not. Duals are loveable but finicky machines. The headshell signal contact systems were not the greatest, and they are overly complex. ULM offered some performance advantages along with even more delicate, fragile parts. Dual should have gold-plated some of the connections.

Contact me for a replacement PDF if you wish. Don

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Re: Big problem with 1219/1229 sleds losing connection in one channel or both

Post by tep392 » 03 Oct 2019 18:09

I had channels dropping intermittently after fixing up my 1219 due to the mute switch contacts not quite opening fully when playing. You can test this by measuring resistance at the audio cable connectors. If the switches are open you should see the normal cartridge resistance value. Closed will give you a low resistance value. A very high value would indicate poor connection at the sled.

PS. I have had good luck with a new old stock TK24 sled that I purchased on Ebay. That's another option if you can't get your old TK14's working correctly. Be carefull with the reproduction TK14's. some of them aren't quite to factory spec.

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