Wax paper caps were the scourge of electronics until the '60s when polypropylene caps began use. They always became leaky, especially in humid environments.
Looks like someone put diodes across the selenium rectifiers. I guess that would work, as the lower forward drop would likely keep the selenium rectifiers in the off state. But, bad practice! Ideally the selenium rectifiers would be removed from circuit and a suitable resistor put in series with the diodes to simulate the voltage drop of the selenium rectifiers.
Ideally, yes, but not the usual practice back in the day. Early silicon rectifiers were also fragile - intolerant of inrush current and low reverse breakdown voltage.
I never understood why anyone liked "halolight" back in the day. Seems like a lighted surround for the CRT makes viewing harder, not easier; especially in a dark room. Early phenolic PC boards were troublesome, with poor heat tolerance resulting in cracking, and also delamination issues when unsoldering/replacing board components. The old tube stuff ran hot.
This takes me back.
Remember when every store had a Tube Tester
those waxy things are actually capacitors (with a wax paper dielectric), 1950's point-to-point construction is like art.
Wax paper caps were the scourge of electronics until the '60s when polypropylene caps began use. They always became leaky, especially in humid environments.
Some of it is art. Some of it is horrible.
Looks like someone put diodes across the selenium rectifiers. I guess that would work, as the lower forward drop would likely keep the selenium rectifiers in the off state. But, bad practice! Ideally the selenium rectifiers would be removed from circuit and a suitable resistor put in series with the diodes to simulate the voltage drop of the selenium rectifiers.
as long as it doesn't let the stench out. 🤣
Ideally, yes, but not the usual practice back in the day. Early silicon rectifiers were also fragile - intolerant of inrush current and low reverse breakdown voltage.
The wax caps are toast .
perhaps the begining of the circuit board era or before that?
Did it leave the factory like that?
Have the same question:D
@@simontist yes.
Pretty much. There are a few replacement parts, but that's normal.
You sure about the age? I would not expect to see a PC board in anything that early.
The "Halo" feature was added to the Sylvania line in 1953.
I never understood why anyone liked "halolight" back in the day. Seems like a lighted surround for the CRT makes viewing harder, not easier; especially in a dark room. Early phenolic PC boards were troublesome, with poor heat tolerance resulting in cracking, and also delamination issues when unsoldering/replacing board components. The old tube stuff ran hot.