New cables for Thorens TD 160

"The odds are slim that both cartridges are bad in
the same way, right?"

Just to be clear, I didn't think the cartridges are bad, but just didn't have enough gain to work well with your pre. It is possible that they both put out about the same amount of voltage. If that's the case then you would have the same problem with either one. That said, I think its more likely to be a cable problem at this point. I would check that first.

A possibility that occurs to me is that two of the four connections are interchanged somewhere in the cabling, such that the RCA center pins of the left and right channel inputs of the PAS-3 are connected to opposite ends of the same coil in the cartridge (corresponding to one of the two channels), and the ground shells of the left and right RCA connectors on the preamp are connected to opposite ends of the other coil in the cartridge (corresponding to the other channel).

Without analyzing the schematic of the PAS-3 I'm not sure what the result of that would be, but it seems conceivable to me that it could manifest itself as the very weak volume you are describing.

I would get a multimeter, if you don't already have one, DISCONNECT THE HEADSHELL LEADS FROM THE CARTRIDGE (so that the voltage that is put out by the meter is not applied to the cartridge), disconnect the RCA plugs from the PAS-3, and measure continuity from each headshell lead to the corresponding center pin or ground shell of the corresponding RCA plug.

Assuming that the headshell leads are color coded white, blue, red, and green:

White should have continuity to the left channel RCA center pin.
Blue should have continuity to the left channel RCA ground shell.
Red should have continuity to the right channel RCA center pin.
Green should have continuity to the right channel RCA ground shell.

Regards,
-- Al

Al, sounds like a good idea, if I had multimeter.
Suppose I should own one. The shop suggests,
"I don’t think the problem is the cables we put in. It’s possible the tonearm wires are bad but also unlikely.

Turntables have weird, subtle problems because the signal level is very low to begin with but I have gotten very good at sorting them out. "

Remember, I have no idea of the history of this table.
But it sure did look clean, except for those cables, which
were original, though broken.

Agree with Almarg. If you don't have a multimeter then try swapping headshell leads around for 1 channel. eg: connect the red headshell lead to the green pin on the cartridge and the green lead to the red pin on the cartridge and see what happens. I suspect the workshop that did the cables inadvertently connected the + & - leads the wrong way around at the turntable end for one channel.

An interesting thought- that the ground and signal
might be reversed. I just tried reversing the connection
on one channel and no change.

I wonder has anyone seen a signal drop from such a
reversal before? You'd think if the theory were sound
(if you will), reversing the +/- would always lead
(again if you will) to a signal gain or drop.

Anyway, back to the shop.