SL1210 Ground / Earth problem with modified Deck / Arm

[aniki]

Hi Folks,

I decided to put my 1210 back to standard and move it on as it's basically pristine and it seemed a shame to mod it too seriously.
However, I've now bought a new 1210 with the 45rpm adaptor hole and pitch slider removed and a nice fresh paint job (only because theres no way I could do this myself and get a good result!)
I have since fitted an Origin Live armboard and tonearm.
All in all it sounds incredible and I'm really content with the sound.
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However, I am certain there is a ground issue somewhere. I don't know enough about electric circuits to really know where to look.
The OL arm has its own ground wire from the arm tube directly to the earth screw on the phono pre-amp.
The problem is that even with the turntable unplugged from the mains, as long as it is connected to the pre-amp, if I touch it, anywhere it sends electric back through the system and trips out my amps.
I first noticed when I had just plugged the deck in and went to replace the platter. As the hole in the platter touched the spindle I saw a tiny spark.
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Now on the standard SL1210, I believe the ground wire serves to ground the arm AND the chassis via the pitch slider screw.
Obviously this is absent on my deck.
Could this be the problem or am I barking up the wrong tree?
Suffice to say the previous deck didn't present this issue.
Any help much appreciated. Cheers.

[aniki]

Just to give you some encouragement, heres the new beast in action:-

http://img.photobucket.com/albums/v236/aniki666/01064889-9BA4-4B44-BF86-8F40E458EC04.jpg

[struth]

Sounds like the deck mains plug earth is not connected to mains earth and you have a live or partially live chassis with one of your pieces of equipment. BE VERY CAREFUL. I would get a professional to look at it(IE the whole system). I have seen similar problems with using the wrong type of mains blocks as well. IE metal ones but no earth present.

[aniki]

Sounds like the deck mains plug earth is not connected to mains earth

The 1210 doesn't have a mains plug earth; it's just 2 core. All other items are earthed and run into a mains block that is also earthed.
The problem occurs even when the deck isn't plugged in to the mains.
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I truly don't believe there is any kind of problem elsewhere. This has only cropped up since acquiring the new deck...

[walpurgis]

Use a meter to check the earthing continuity from the headshell to the arm cable and also from the TT chassis to the arm cable. I expect it should all earth through the arm cable outer braid (or screen if it has one). A loose tag on the cartridge or slack phono plug can also cause hum.

[struth]

The 1210 doesn't have a mains plug earth; it's just 2 core. All other items are earthed and run into a mains block that is also earthed.
The problem occurs even when the deck isn't plugged in to the mains.
-
I truly don't believe there is any kind of problem elsewhere. This has only cropped up since acquiring the new deck...

no the 1210 is double insulated but there is a problem with earths in the system if you are getting a spark and causing tripping. there must be some voltage escaping to earth

[CageyH]

I had an earth problem with a modified deck. I ran an additional cable from the main earth point of the PCB to the phono stage and the problem went away.

[Tarzan]

Hi Adam, your Techie looks lovely, may l ask who done the work and paint job on it?

[aniki]

I had an earth problem with a modified deck. I ran an additional cable from the main earth point of the PCB to the phono stage and the problem went away.

Thanks. I'm pretty certain this is the issue. Having done a bit of digging I can now confirm my earlier suspicion that on a standard deck the chassis / tonearm ground works as follows:-
Ground cable from pitch slider mounting screw to tonearm pcb. Ground cable from tonearm to tonearm pcb. tonearm pcb to flying lead for pre-amp connection.
As I bought this unti with the pitch slider removed this screw and extra lead was obviously already absent.
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So now the plan is to either take a new lead from the chassis to pre-amp or replicate the standard setup but taking a lead from the chassis and splicing it into the existing tonearm ground lead somewhere under the base of the tonearm.
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I'll let you know how it transpires!

[aniki]

Hi Adam, your Techie looks lovely, may l ask who done the work and paint job on it?

Thanks. I bought the bare unit from a seller on a well known auction site. He has Cardiff in his seller name as that's where he's based.
I now need to get in touch with him and tell him he needs to leave on the chassis ground leads! :-)

[aniki]

UPDATE!
I think I may have been barking up the wrong tree.
Having now switched a few bits of kit around including a totally stock SL1210, I think the problem is me!

The kit is not leaking voltage, I am. What is happening is I am statically charged. As soon as I touch the TT it is sending the charge to the ground terminal on my phono pre-amp which in turn sends the charge to line level pre-amp which in turn mutes the output to protect the equipment!
Any suggestions as to how to get rid of this charge before flipping records, touching buttons etc?
cheers

[walpurgis]

Wearing a chain mail shirt connected to an earthing rod sunk into the floor of your listening room may help. :D

[rdpx]

Stop shuffling about in your nylon shoes on that acrylic carpet! http://www.electrostatics.net/articles/static_build_up_on_people.htm

[aniki]

Stop shuffling about in your nylon shoes on that acrylic carpet! http://www.electrostatics.net/articles/static_build_up_on_people.htm

Found a solution:-

http://img.photobucket.com/albums/v236/aniki666/90C18D43-2228-4288-A73A-E6A99862628F.jpg

The thing dangling from the wall panel is a 150kohm resistor spliced between a bit of wire and some crocodile clips. I use this when working on my guitar valve amp.
I just touch the croc clip before touching the hifi and Voila! No clicks, pops, sparks or mutes :-)

[struth]

so what your saying is your a real live wire:D

I used to attract static like crazy. dunno why and dont now