Wireless Set No. 52 Canadian - Project

[David Dunlop]

Hello Chris.

Interesting you should comment on the vibrator.

When I first took a look at the circuit diagram for the ZE-11 Supply, I assumed the two options for input (12V DC Battery, or, 115/230 V AC Mains) were fully exclusive of one another based on placement of the 6-pin Plug and the spring loaded switch setup. The current vibrator could very well be the factory original one. It is completely generic in look, with only “12 V” and the Canadian Marconi Part Number stencilled on the end of it in black block letters. It is also dead.

I did not worry too much about the vibrator status as I reasoned that since it was isolated by choosing the AC Mode of operation, and my sole intent was to be using the ZE-11 as a Mains based supply for the Remote Receiver, all would be OK.

Having solved the C25A/B capacitor problem and knowing I now had a good working OZ4 in the system, everything checked out OK downstream of the OZ4 socket. But when connected to the AC Mains, I now discovered the input voltages to pins 3 and 5 of the OZ4 are not matched. I am getting 200V AC on one side and 150V AC on the other. Should be 200V each. The end result is just 7 V DC at the HT pin on the Jones Socket, instead of the expected 150 V. I am also getting strange, intermittent voltage spikes ranging randomly from 10 to 51 volts, with an immediate return to the baseline 7 volts.

The first two things that came to mind were that the secondary windings on the transformer for the AC side had gone, but it was also possible that one of the RF Choke pairing L13A, L13B had shorted. The only way I can see to test which option is correct is to dismount the RF Choke can on the side of the chassis to exposed the two terminals feeding from the transformer. If the two feeds from the transformer are feeding 200 volts AC, then one of the chokes has failed. Worst case scenario, the secondary on the transformer is shot.

Then it crossed my mind the dead vibrator might be a factor, if it is still active in some way even when the supply is in AC Mode. Still trying to sort that out in my head. The price I am paying from being away from electronics for 30 years. I do know that if the vibrator is in the socket, or removed, there is no change in the results I am getting at the Jones Socket. A good working order vibrator could clarify that for me. The manual specs it out as follows:

VIBRATORS, Non-Sync. 12V, 4-Amp 1-1/2 inch diam, 3-1/4 inch long.

Not sure off the top of my head if that is a match for the one used in the 19-Set Supply, but it is a convenient point to take some time to mull over, with a stiff drink.

David