[Mitsuman]

Apparently while attempting to tweak one more degree of VTA out of my tonearm this past weekend, I broke/damaged a ground wire in the tonearm/pivot assembly. Now I'm getting a terrible hum if I grab the metal sides of the cartridge or at various points along the arc if I swing the tonearm. Someone give me some words of encouragement that I can rewire my tonearm. 

[neobop]

I hate it when that happens. 
Don't despair, if it's just the ground it might be easier than you think.
What kind of arm/table is it?

Look on the bright side. Your cart is still in one piece.

 

[Mitsuman]

One of my beloved Mitsu DP-EC2's. There are pics in my gallery. And  is right.

[neobop]

Did you happen to get a service manual for the EC-1, while you were a member at VE?  It could come in handy, but you might not need it. If you have it, look for any special procedures for disassembly and the wiring scheme. 

Remove the dust cover, headshell, counterweight, and platter. Tie down the arm. Then figure out how you're going to support it when you remove the feet and bottom panel.  (Hint- protective cloth over bricks or other structure, perhaps an old chair with the bottom removed and rigged for TT repair.) If the dust cover is sturdy, you might get away with putting down a cloth and resting it on the cover.  That's not recommended.
You might see the tonearm wires exiting the pillar without having to remove anything else.  On an automatic, often the wires go to a junction. Hopefully, it will be straightforward and you'll see the problem.  Sometimes the ground wire is  bundled with others at that junction, but first you have to see what's going on.

[Mitsuman]

Did you happen to get a service manual for the EC-1, while you were a member at VE?  It could come in handy, but you might not need it. If you have it, look for any special procedures for disassembly and the wiring scheme. 

Remove the dust cover, headshell, counterweight, and platter. Tie down the arm. Then figure out how you're going to support it when you remove the feet and bottom panel.  (Hint- protective cloth over bricks or other structure, perhaps an old chair with the bottom removed and rigged for TT repair.) If the dust cover is sturdy, you might get away with putting down a cloth and resting it on the cover.  That's not recommended.
You might see the tonearm wires exiting the pillar without having to remove anything else.  On an automatic, often the wires go to a junction. Hopefully, it will be straightforward and you'll see the problem.  Sometimes the ground wire is  bundled with others at that junction, but first you have to see what's going on.

Neo, I already had an original service manual for the EC2. Detailed disassembly information is not really in there I'm afraid. 

[neobop]

No detailed disassembly is good. It means no special precautions so you don't break something else inadvertently.  Do you have a multimeter?  Do you solder?  Perhaps I assume too much. 

In your orig post you said, "I broke/damaged a ground wire in the tonearm/pivot assembly." 
I assumed you don't know the actual location or manner of the fault.  Is this correct?

My thinking is, perhaps you can repair the ground and not have to mess with the four signal wires. There should be pictures/description of the arm wiring in the manual. See where the ground wire is terminated in the arm.  It might go to a tiny screw somewhere on the pillar or back of the arm tube.

I don't know how DIY you are. Maybe I shouldn't encourage you to do this.  It's like working on your car. Many guys can change their oil no problem. Some guys can replace the radiator. When it comes to the water pump/timing belt or a new clutch, I take it to my mechanic. As long as you can take the bottom off and put it back together again, you have a chance for an easy fix or at least identify the problem. BTW, if you try this, look for any small parts that may have fallen off.

[Elizabeth]

A suggestion do not disassemble the tonearm bearing if you can at all avoid it.
Then. you might be able to pull one wire through without damaging the others. Solder a new 28ga or smaller 30ga? to the old ground wire. and just pull it through VERY carefully.
If it sticks ???
Anyway that is what i would try a first thing.
If it does not go so well. or gets stuck.
Then all new wires pulled through would be the second try.
I rewired ONE tonearm many years ago, and do not ever want to  have to do it again. (most of the problems are with the bearing.. so the advice to leave it alone is for real.)
Having a professional redo it, is always possible if you can't pull new wires through with the old ones.
So do not go crazy and smash stuff if it too hard to do.

[Mitsuman]

Well, it's a good news/bad news story. 

Took the deck apart, and the good news is there is no problem with the tonearm wiring or any soldered connections. I swapped the longhorned Grado Gold1/8MZ combo out after putting the deck back together, and put in my AT 440mla. No hum, nothing.

I don't know if somehow the Grado got damaged internally.  I'm going to replace the headshell leads and put it on another deck and see what happens. Thanks to everyone for the suggestions/encouragement. 

[Russellc]

Well, it's a good news/bad news story. 

Took the deck apart, and the good news is there is no problem with the tonearm wiring or any soldered connections. I swapped the longhorned Grado Gold1/8MZ combo out after putting the deck back together, and put in my AT 440mla. No hum, nothing.

I don't know if somehow the Grado got damaged internally.  I'm going to replace the headshell leads and put it on another deck and see what happens. Thanks to everyone for the suggestions/encouragement. 

Could be the headshell leads.  I have a Magnepan Unitrac that has a removeable headshell with tiny leads that go to a small plug that fits on a tiny male recepticle on the end of the arm.  One of them will occasionally hum when I remount a different cartridge....usually just removing the plug and re seating it does the trick, or redressing the hair like leads.


Russellc

[Mitsuman]

Could be the headshell leads.  I have a Magnepan Unitrac that has a removeable headshell with tiny leads that go to a small plug that fits on a tiny male recepticle on the end of the arm.  One of them will occasionally hum when I remount a different cartridge....usually just removing the plug and re seating it does the trick, or redressing the hair like leads.


Russellc

I'm hoping you're correct, because I had recently purchased some "audiophile" grade Litz headshell leads. You can look at these things funny and break them they're so fragile. I wonder if I broke one of the tiny wires during my hamfisted reinstallation.