Dual 1019 head shell contact blades.

[Hugues TR4]

Hi All Dual enthusiasts and specialists,

I'm still busy trying to fix and upgrade my good old 1019 and I have a question for you guys.
When you take the cartridge holder head shell off the tonearm, it shows five copper contact blades.
Four of them are connecting to the cart's plugs through different coloured wires (L,R,LG RG).
The middle one is part of a shield which is attached to the bottom of the plastic shell itself. It does not looks like being connected to the cart itself, whether clip-on system or 1/2" screws fitting.
I wonder what the purpose of this center blade could be, and could it have any influence on the hiss and hum I'm experiencing at higher volume (past 2 o'clock position) even when changing head shell?
Thanks a lot for your opinion and usual good advice!

Cheers,

Hugh.

[Hugues TR4]

Hello Folks,
Am I hitting such a deep mystery that nobody seems to be able to enlighten me about this fifth contact blade?
This hum/buzz/hiss problem seems to affect quite a lot of Dual TT's with no separate ground to the amp, so I would have thought it might have something to do with this center blade, but I see no direct connexion with the cart. Hence my question to the experts!
Just waiting for a brand new TK12 head shell I managed to find on e-Bay, to which I plan to fit my new Shure M97xE cart and I'd like to know what to look for before adjusting everything.
Would like my 1019 to really sound like new (even better with the new cart.)
Thanks a lot for your usual help!

Cheers,

Hugh.

[muradeli]

In my Dual 1010 the central strip in the tonarm part is connected by short wire (hardly visible) with right channel minus. With the cartridge holder inserted, the cartridge holder brass shield contacts right channel minus.

[dualref]

Yes, corrosion on the cartridge holder blades could definitely be a source of hum & buzz. I recommend cleaning these contacts both on the cartridge holder and inside the headshell at the first sign of hum.

Maybe this will make it clearer, right from the Service Manual. It's available for downloading in the VE Library Section:

[Hugues TR4]

Hello Muradeli and dualref,

Thanks a lot for your contribution.
Cleaned all contacts thoroughly with CRC contact cleaner and Q-tip: not much change...
On the other hand, examined closely diagrams and pictures in both owner and service manuals: no mention at all of this fifth blade! On the cart holder itself, just behind the blade in question, there is a square hole marked with blue paint: on the bottom of it, you can see a small extension of the shield frame with a hole for apparently soldering some unused connexion (?) very visible if you turn the shell on its back.
Got a spare one and the set up is identical to my original one which came with the TT back in 1969 when I bought it.
Any suggestions at all??? Could it mean that it only concerns the 1010 as muradeli mentioned in his reply?
Thanks in advance!

Cheers,

Hugh.

[muradeli]

For Dual 1019 the same thing: the brass shield in the cartridge holder will be connected with right channel minus after you insert it in tonarm.I understand, you said your Dual TT's has no separate ground to the amp? The 1019 I saw always had it.

[Hugues TR4]

Hi Muradeli,
My 1019 has definitely no separate wire to get connected to amp. Tried to connect earth of the amp directly to some earth source of the TT (arm or any other nude spot on the chassis): only got loud hum.
Any other suggestion?

[muradeli]

This link may help:
http://www.vinylengine.com/turntable_forum/viewtopic.php?t=35252

[Hugues TR4]

Hi muradeli,

Thanks a lot for your tip.
Will try and put a separate gnd wire as shown on the drawing and see what it changes.
Will let you know about the results.
Many thanks again,
Cheers,

Hugh.

[Hugues TR4]

Hi all,

muradeli: Did try and connect a separate ground wire from the chassis to the amp (it has a dedicated contact for this purpose): all I got was an even louder buzz!
Also tried to connect the copper shield to RG (Blue) as mentioned with no result.
Managed to find a brand new head shell on E-bay (from Germany) with no corrosion at all, cleaned it with CRC: still the same...
Fortunately, the buzz only gets annoying past 6/10 volume position, but it's a matter of principle: Tape, CD and Tape2 don't buzz, so why TT?
Also tried reversing all the mains plugs feeding the HiFi set. Nada! The only small result I got was when I separated mains lead from phono plugs, but only slightly. There is probably a ground loop somewhere...
Will go on investigating. If you happen to be able to suggest something else, you're most wecome!!!
Thanks a lot anyway to you and also Dualref for your help.

Cheers,

Hugh.

[fscl]

Anyone have suggestions on affixing the blades back onto the cartridge holder? Yeah, expoxy is the simple answer, however, was wondering if any VE members would like to share.... something a bit different....

Was considering hot soldering iron melting some plastic onto / into hole allowing for a bit of blade freeplay as originally designed.....

Solutions welcome.....

Fred

[Hugues TR4]

Hi Fred,
Already had the opportunity to fix two headshells by just using a bit of superglue, but of course the rear part of the blade gets stuck to the plastic.
mrow2 already suggested the melting plastic method and it seems to work (might be on one of his posts).
By the way, I managed to find a brand new shell on E-bay recently and the blades are affixed quite tightly in their lodgings: no play at all in the rear sections which makes the shell quite difficult to fit in its place on the tonearm (very tight) but assures a good contact.
Another way could be using the top part of a heated pin head to keep the blade in its place...(?... just a thought).
Couldn't think of any other method...

Cheers,

Hugh.

[fscl]

Eureka....... Thanks.....

There's a hobby shop selling dollhouse furnishings, including minature screws....... I haven't been in recently, however, I'm thinking one of these minature screws (door hinges, etc...) would fit into the blade slot / hole and can be driven in with heat...... and the screw anchored with a shot of superglue, hopefully, it won't stick to the metal?....

Fred