Hi Doug,
There is nothing similar to PCB inside a filterette capacitor, once for all .
I have sacrificed a Tobe capacitor from a Tobe filter to show that :
viewtopic.php?t=295773
And yes these are very good capacitors.
Why would they have filled up a very low voltage capacitor with PCB ?
The PCB was used to insulate with high voltages, suppress arcing, and at the same time act as a coolant.
Is that necessary withing a 6V or 12V or even 24V circuit ?
People thought that the capacitors were full of PCB because when there is a short in a filterette capacitor, it heats up a lot and the wax simply melts, flowing outside the container.
As you know beeswax becomes black when melting !
If the pressure increases inside the cap due to the wax melting, yes it could explode.
What else... It's under the filterette cover.
It happened to a very large cap in one of my first radios, a WS-38, and I'm still alive ! I had a lot of work cleaning up the acid spilled everywhere.
It happened again more recently with one of these "f.....g" tantalum "bad caps" made during the coltan shortage period.
Nice and loud explosion .
What else? I'm still alive... and I have repaired the PC power supply by just replaing the cap.
It's much better to have wax projections than acid from modern electrolytic capacitors.
And I'm still very happy with my filterette correctly wired as it should be .
Yves