The wiring rundown is here.
Wiring for the tonearm to the preamp was as follows:
- Pin 1- no connection
- Pin 2- + positive
- Pin 3- - negative
- Shell ground- cable shield
Why was it wired like that? I agree the typical connection is pin 1 for the shield. See excerpt from the Elac PPA-2 Manual:
"Typically a balanced connection will be more immune to hum, so it would be the preferred connection. However, you must be careful that the shell of the XLR is not connected directly to the ground line within the XLR connector ( That sentence is a little confusing but I take it to mean that the shell of the XLR should not be connected to pin 1). They SHOULD be independent. The shell is the external shield of the cable and connector, and should be the CHASSIS connection. The ground wire within the XLR is twisted with the (+) and (-) balanced and should be the signal or tonearm ground. This can all be confirmed with an Ohm meter. "
The PPA-2 has two ground lugs, one for tone arm ground (labeled ground) and one for chassis ground (labeled chassis). Since there is no chassis ground on the GT2000, that lug remains unused. The tonearm ground is connected via the other ground lug.
The cable shield is NOT connected at the TT end, but is connected via XLR shell to the chassis ground.