This set was bought in by a third party, who just said it did not work! After removing the chassis and Hoovering away fifty years worth of dust and cobwebs, it was clear this set had never had any work done on it since it was made. Apparently, it had been in daily use until it stopped working recently.
A quick check round with a meter pointed to the dropper resistor being open-circuit. This is contained in an asbestos lined shield, with a plaxolin mounting strip to one side. This has pillars riveted in place, which the resistor is fixed to, and solder tags beneath the rivet heads for the connection wires. In this case, the plaxolin had burnt away, so the solder tag was making a loose connection to the pillar. Since the remaining mounts still securely held the dropper, the solution was simply to solder a piece of tinned-copper wire between the dropper and the tag.
Everything else looked OK so I connected a meter across the HT and switched it on. The voltage climbed to about 100V, and the sound produced gave the impression that "Talk Radio" was under twenty feet of water (some might say that is a good place for it)! The main smoothing capacitor (32uF+16uF at 275V) was open-circuit, and a replacement gave excellent results. I replaced a few of the wax-paper capacitors as a precaution. No other work was needed.
The valves were clearly the originals and, although
I did not test them, the performance of the set suggested they had plenty of
life left! It is nice to see a set that has clearly been cared for and enjoyed,
instead of suffering years of neglect.
The photo above was scanned from the book Bakelite Radios.