Wireless Set No. 52 Canadian - Project

[Chris Suslowicz]

Originally Posted by David Dunlop

However, (Interesting how that word can pop up so often in restoration work), once the connector socket assembly was remounted to the chassis and power reapplied, I no longer have +12 V anywhere in the system and no +150 V showing on HT Mode on the meter. Every valve is stone cold inactive.

I switched the Remote Supply to my backup receiver and that receiver lit up straight away. All voltages normal and the meter shows about half the valves with normal readings, the remainder with nil readout. While hooked up, I took readings from the terminal strips on the back of the connector socket. The HT was 155.5 V with the meter showing spot on 150 V. The LT reading at the connector terminal was 2.39 V. Struck me as a bit low but all items downstream from there on the LT side were responding correctly.

Back to the Remote Receiver chassis to check the same two connector socket voltage values. The HT terminal came in at 218.5 V. This is very close to the raw output HT from the Remote Supply. The LT reading was 0.75 V.

What initially comes to mind is a short in the system and with the missing contact on the connector socket, I am wondering if the screw stub and/or nut inside may finally have broken free and moved into contact with internal circuits. I briefly had a working system when I first jumpered the broken relay wire behind the connector socket assembly. Maybe all the jostling about of the socket assembly while resoldering bumped the broken hardware free inside to run amok.

Sigh!

David

What you've got there is no heater supply, so there's no load on the HT. The very low heater voltage could be due to a short circuit (loose bit of metal in the back of the connector, shorting something to ground), or to a high resistance (dry) soldered joint in the LT circuit.

You could remove all the valves and measure the resistance between +12V and chassis - with no valves fitted it should be very high resistance (or open circuit).

If it is a short circuit, don't risk the power supply by running it for more than a few seconds - I don't think there are any fuses in the LT circuit, and it will overload the transformer.

Chris.