WS19 Headphones - how to make operational
 

Hello,
I'm hoping someone on MLU will be able to suggest ways to reactivate a number of WWII 19 set headphones in my collection. I have a three sets (of 4 total) that I can't seem to get to work. At the moment my only test is when I press the "Call Commander" button on the Driver's Control Unit, the buzzer is clearly audible in the earcups of the operational set. The same test doesn't produce results in the others. Is there a way to kickstart these, just in case the speakers need a little prodding to reactivate?
Additionally, would or could these be tested with modern stereo equipment, or are they simply too primitive or of the wrong impedance to reproduce sound?
I am in the process of setting up the complete wiring system in a Sherman tank, complete with the three Control Units, and ideally would like to get at least two headphones working so that two "Crewmembers" could communicate with each other. The wiring is up and running and appears to be working fine, the lights come on and the buzzer works, I simply need two working headsets to take the investigation one step further.
Thanks for any assistance or advice you can offer.
Regards, Patrick

Progress Photos
 

Here's two photos of my Sherman M4 turret WS19 installation whose shell I've built entirely from scratch. I've constructed the rear portion of the turret out of plywood and plaster and made the two commander's seats (one yet to be installed) out of laser-cut plywood. These have been constructed to be fully functioning in either up or down position. The Thompson magazine rack is a combination of white acrylic sheet, 3D printing for the magazine slides, and aluminum rivets to hold the slides in place. The turret wiring box is NOS from the early 1950s and all power will actually come into the box for distribution.
The transmitter/receiver is a mint-condition MkII and with luck, once connected to aerials it will be able to receive signals and the "crew" will be able to talk to each other. Once the interior is fully outfitted and painted a gloss white the radio will be installed on an original PSU/transmitter tray resting on, but not putting weight on, four original shock-absorbers. I have all the cables leading to the variometer and antennas, and have an original canvas dustcover for authenticity. Surrounding it will be a Spare Tube Box, a First Aid kit, 2 flair-cartridge metal containers, a set of Sherman tank flags in their canvas bag, and a morse code key serving the radio. I am trying to keep original parts wherever possible.

First thing is to make sure the snatch plug contacts are clean. Next take your multimeter on the ohms range and measure continuity between plug and each headphone. Then check continuity between each side of each earpiece. If there's no reading on any circuit then most likely an open coil. The earpieces are wired in series from pin 2 to one side, a jumper between earpieces and other side going to pin 3.

WS19 Headphones
 

Thanks Bruce for the information,
I don't happen to have the test equipment you mention but a friend of mine does, so hopefully soon I can test out my four sets and get at least two operational.
Regards, Patrick

Evening, Patrick.

If you need a schematic of the headset and drop cord wiring to follow along with for the continuity checks, there is a very good one in Figure 12 on Page 135 of the Working Instructions Manual for the WS Cdn No. 19 Mark III.

Don't panic if any of your headset receivers, or microphone elements, turn out to be duds. They can still be found,


David