Turntable Right Channel Dropping Out; Grounding Cartridge Body Brings It Back

@lewm Well, it’s not the cartridge! The Stanton cart on the turntable with balanced interconnects failed on the LEFT channel, just like The Vessel cart failed on the Right channel. This may well be due to different pinouts on the cartridges themselves. The headshell is wired for right channel on the right side, looking at the front of the cartridge; while the left channel is wired on the left side. For the headshell, the positive connectors for each channel is mounted on top; the negative is on the bottom. The pattern on The Vessel cartridge connects the pins on the left side of the headshell to the right side of the cartridge, and swaps the positive connections from top of the headshell to bottom of the cartridge.
The Stanton is wired in a cross-cross pattern: The right positive connector (red) goes to the bottom left, and the right negative (green) goes to the top right; while the positive left channel (white) goes to the bottom right pin, and the negative left channel (blue) goes to the top left pin, the pin with the ground strap on it. I believe I wired it up to match the headshell I am using, but it is easy to check. All the wire colors are called out on the internal end of the wires on the circuit board to which they’re attached. N
 

As far as failure symptoms: I believe I was able to play both sides of one stereo record flawlessly, but I started losing the left channel on the first side of the second stereo record. It started failing about every other track after that. Tapping on the tonearm did not bring it back; only if I disconnected the headshell was the tapping effective. 
All the pins had spring action on them; it was difficult to tell if any of them were sunken in a bit. 
The most effective method to recover the full sound of the recording was to touch the tone arm to the exposed portion of the pins on the left side of the cartridge (the red and blue wires, plus the exposed ground strap) which would produce a dull ‘thump’ at the speaker. 
I tried a mono record, with the phono stage set to mono, and without the mono button engaged; but I still lost sound. It just shrinks the sound stage down to the singer and the main accompanying instrument, in this case, a guitar. I lose the surface noise, then the high treble, but mostly, I notice a drop in volume and clarity. It all turns to mud. 
 

I discovered the cable’s ground wire detached, and reattached it to first the chassis ground, and then to the signal ground. I tried my switch in both positions, but the issue did not go away. I left the wire on the signal terminal and set the switch also to signal. With the wire in my hand, but unattached, there was a loud 60( or 120 cycle hum at the speakers. 
 

The pinout of the cartridge shouldn’t matter if the signal wires are connected correctly at the headshell, should they? I’ll verify the headshell connections tomorrow; it wouldn’t be the first time I wired something up backwards. (Burned up a perfectly good floppy drive once by failing to turn the Molex connector right side up.)

I verified that the wire colors are correct on both sides of the bayonet connectors at the cartridge end of the tonearm. As stated above, the failure symptoms are an intermittent loss of volume on one channel or another when playing in stereo; both channels appear affected when phono stage is set to ‘mono’. Actually, the sound fails in both channels; it’s just that one channel, or the other, completely fades out first—depending on which cartridge is being employed. (The right channel drops out on The Vessel cartridge; the left channel drops out on the Stanton 500 cartridge.)

I still don’t know what’s going on, it acts, to me at least, as though a capacitor somewhere in the circuit is failing; that it slowly turns from a component capable of passing an AC signal to a resistor than attenuates it to the point of extinction.  And again, it is as if the stylus brush trick ‘drains the charge’ so-to-speak, allowing the capacitor to function again briefly. This is all a fanciful conjecture, of course, it’s just my way of making sense of the symptoms. 
 

There are a few more things I’m going to try:

(1) Open up the offending turntable to examine all connections at the bearing end of the tonearm all the way to the interconnects themselves. 
 

(2) Take at least one, if not both, of the subwoofers connected to the line stage out of the circuit in case there is a ground loop developing. I’m pretty sure one of them is NOT plugged in to the same outlet, although I think everything is on the same circuit. (This topic came up on a recent, similar thread.)

(3) If all these measures fail to isolate or resolve the issue, I’m going to swap out the amp and line stage with my tube gear. (I have to do this anyway since the tube preamp recently failed, and I need to remove it from the system for service in any case.)
 

(4) Unfortunately, I can’t swap out a prime candidate for electronic failure: the ELAC phono stage, because I don’t have another one which accepts balanced connections. So, as a last resort, I shall re-install the unbalanced RCA interconnects. The unbalanced interconnects will allow me to remove the current phono stage entirely, if necessary, and go directly into the McIntosh C100 line stage.

i’ll get back with results when I have them.

@oldrooney 

I would use a multimeter meter to check continuity and resistance from tonearm bayonet pin to RCA/XLR. Move the arm and cables when using the meter to see if motion affects the measurements.

Then from the above list I would do number 4 first.

By the way, with regards to the Cardas wire - if you use solder flux the insulation melts much quicker. I always pre tin both the wire and connector to minimise time on fragile pins when soldering.

@dover Thanks for responding. I’ll Ohm out the wires later today. Watched a video on YouTube this morning by The Turntable Man, it’s no big thing to Ohm out from existing cartridge to cable’s phono stage termination. 
 

[Note: I accidentally deleted an earlier post on the same topic.]