On Tue, 7 Feb 2017, Benderthe.evilrobot wrote:
wrote in message
...
On Mon, 06 Feb 2017 21:54:54 -0800, Spare Change
wrote:
On Feb 2, 2017, wrote
(in ):
Why should someone replace ALL the capacitors on old Tube equipment?
https://en.wikipedia.org/wiki/Glowing_plate#Common_Occurrences
Several causes listed are caused by shorted or leaking capacitors. It's a
tube killer.
A;so the sinle largest killer of hard to replace power transformers.
Not to mention a leaky grid coupling cap can pass a large DC voltage from the
plate of the previous stage. I've seen tubes that got so hot the glass melted
and the vacuum wrapped it round the internal structure like cling film.
If it happens in Ham gear - the PA tubes are seriously expensive.
There are stories of Collins receivers, I forget which model, where the
capacitor feeding the mechanical filter can go bad, and the result is
a ruined mechanical filter, it can't handle the DC going through it.
SO that's the sort of thing knowledge that is out there for people coming
to an old receiver for the first time.
Michael