Hi,
On Wednesday 13 December 2000 01:03, you wrote:
> understand everything well enough to ask better questions:
> > If the 'burn mark' on the inside of the neck of the tube is
> > silvery-edged and/or mettallic looking, then it is possible that is the
> > residue of the "getter" flash. To sweep out the last of the reactive
> > gas molecules that
>
> Yeah, silvery, not flaky. So that's a good thing
Great, then it's not a burn, it's a good sign. If the silvery deposit becomes
hazy or translucent, it means that the tube is losing vacuum. Tubes with weak
vacuum run hot, which compounds the loss of life.
However, your problem with the intermittent heater is a pretty common thing
to have happend in the old days. There is a way to fix it, usually... You
will need to find someone with a picture tube tester that has the filament
'repair' feature. What this really is, is a fairly large (500uf or better)
capacitor, that gets charged up to about 250VDC and then is applied across
the (open) heater contacts on the tube. It helps to first jar the tube
slightly, and test to make sure that the heater is (at least at that moment)
totally open, before applying the voltage.
Now the voltage is applied. The tube is then jarred slightly, until the open
heater makes a light contact, at which time the cap discharges like a mini
arc-welder and tags the heater filament back in place. This works well, and
can be done many times. If your heater is open internally, this is the best
(and only) route for effecting a repair.
Good luck, I hope you are able to fix it.
--
Bill Layer
Sales Technician
<b.layer_at_vikingelectronics.com>
Received on Wed Dec 13 2000 - 10:08:15 GMT