I have a Bush radio presented to my Grandfather in 1956. He used it
daily, but it hasn't been used for at least 20 years, probably nearer
40, and today, it is silent. The dial is illuminated and all the valves
are glowing, but nothing from the speaker, not even crackling when dials
(on/off volume, tone, tuning and waveband) are rotated. Tried an
external speaker, still silent.
Any thoughts? Can a valve fail but still glow? The extent of my
knowledge is don't poke around because of high voltages!
Loss of HV at a guess...rectifier tubes can fail, resistors fail, caps
fail etc, etc
There are plenty of Youtube videos with good information on servicing
Best advice really, is that if you are not confident around modest
voltages (150-300v) then find someone who is :)
Yes indeed. One fairly safe thing to do is to carefully remove each valve
from its holder. There could be screening cans and spring retainers, then a
squirt of contact cleaner in the holes and a wipe over of the pins. Do them
one at a time, and wiggle them as they go in. When all done try it. Probably
be a waste of time, but you might at least have some life indications from
As I said before though, if the ht fuse has gone then its probably really a
job for a competent engineer.
This newsgroup posting comes to you directly from...
Don't spray with contact cleaner! Some valve bases were made out of poor
quality paxolin/tuffnel and the contact cleaner can cause the HT to
track across with a possible fire. This was very apparent on some
"vintage" Ferguson Radiograms with the valve bases and waveband
selection switch. I remeber them well from my apprenticeship days.
If you do try removing the valves, grip them by their bases if they
have them, rather than by the glass envelope, as the glue holding the
envelope to the base gets brittle with the heat and over time, and you
may find yourself holding the envelope with a bundle of broken wires
sticking out of the bottom, and the base still firmly in its socket.
In the early 60s I fixed our old wartime Ministry of Supply radio by
replacing the diode, which had failed, and there was a lead from a
tetrode that had come adrift from somewhere so I soldered it to the HT
line. It worked well enough after that.
The diode going o/c would be enough to mean nothing at all from the
"Hard" and "Soft" Brexit are code words for Leaving or Staying in the EU,
rather than for the terms of our departure.
Yes. Although the length of time it will glow for if the vacuum inside
the envelope has deteriorated is severely limited. Usually it is old HT
capacitors that tend to give up the ghost first - sometimes by dripping
flaming wax onto the floor so don't leave it unattended!
For a really spectacular effect have the Selenium rectifier in some
old sets fail. The smell stays until you sell the house which you
usually have to do after about 6 months when you realise the aroma is
never going to fade.
Most likely power supply related. Usually there is a huge hum, but if the
capacitors shorted out then maybe the ht fuse has gone. For something like
this, if you really do want it to work, be prepared to let a specialist
have it for at least a couple of months and a big bill.
The trick with old gear is to use them at least once every few months. I
have done this with a Rogers amp and its still working from 1965.
This newsgroup posting comes to you directly from...
At that age most of the capacitors, both paper and electrolytic will
have dried out and failed. Without replacing these any other fault
finding is futile. "Recapping" (replacing all the wax paper and
electrolytic capacitors) is fairly straightforward if you have
soldering skills and modern replacement components are cheap and
physically a lot smaller than the old ones so there is usually space
to fit them in. There is no guarantee that this will cure the problem
but it usually does.
If you don't have moderate skill with a soldering iron and working on
old radios you may have to go hunting an aged wireless repairer, there
are still a few about.
Yes. What do you mean by "glow"? A redish glow from deep inside the
metal work inside the valve or a dim purple/blueish glow around the
The redish glow is the heater, required to release electrons from the
cathode. The blueish glow has various sources and isn't generaly a
problem but does indicate that the HT is present. Not having ablueish
glow doesn't mean there is no HT.
As others have said, inspect the thing looking for obviously
burnt/failed parts. Reseat the valves, no contact cleaner. The getta
on the inside of the glass envelope (probably at the top) of each
valve should be silvery and can be quite a dark silvery. If it's
white air has got in and the valve is useless.
On Friday, 31 August 2018 16:30:08 UTC+1, Graeme wrote:
I'd start by checking the HT supply. But as others have said most of:
HT is 100s of volts. You need basic comptence to play with it
There will be capacitor failures that need fixing to avoid further damage
Many old valve sets were transformerless live chassis sets, again you need to understand the issues with that.
Valves are usually replaceable or repairable. More likely to be faulty elsewhere.
If you feel confident looking at a few hundreds volts than suggest with
a decent multimeter if you have one look at all the numbers on the
valves and Google them until you find one entitled "rectifier" then have
a look at the base diagram and ignore the heater pins but look for the
anode should be two off (maybe one in some designs) and the cathode that
should have around 200 or more volts DC on it. Negative lead or "- "lead
to the chassis metalwork!
If it doesn't switch to AC volts then check the anodes and see if there
around the same or more on them. Then report back here!
WARNING only attempt these measurements if you are sure you can do them
and feel confident to do so and best bet keep ONE hand in your pocket
that prevents an across the chest electric shock!
BUT ONLY IF YOU FEEL COMPETENT TO DO SO!!!
On Fri, 31 Aug 2018 12:18:56 -0700 (PDT), firstname.lastname@example.org wrote:
When I was a lad, I was given a transformerless radio. The chassis was
connected to the mains live, rather than to the neutral. Whether it
was meant to be like that or just that someone had wired the plug the
wrong way round, I can't remember, but I discovered it the painful way
when trying to set up an earth wire to the chassis!
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