Valve/tube, A/R fault

[N_Cook]

Well that is what Avo calls it, I've never come across one before. ECC83
with curious cyclic swirling breaking-surf whitish-noise and clicks.
Putting on Avo 160 tester showed <>short in A/R setting, I've never had
before, A/R here stands for cold checking Anodes To Remaining electrodes.
DVM cold resistance checking pin to pin showed about 9K between an anode and
its grid. I will replace it but is there any point in blasting with some
high voltage to vaporize whatever is bridging, for a known
unreliable/short-term spare. I'm aware that a valve with leaky C to H, then
running the valve with 10 or 12V on the heaters insted of 6.3V so they glow
like bulbs for a few seconds, will knock back the bridging deposit for a few
months or even years.

 

[Meat Plow]

Well that is what Avo calls it, I've never come across one before. ECC83
with curious cyclic swirling breaking-surf whitish-noise and clicks.
Putting on Avo 160 tester showed <>short in A/R setting, I've never had
before, A/R here stands for cold checking Anodes To Remaining
electrodes. DVM cold resistance checking pin to pin showed about 9K
between an anode and its grid. I will replace it but is there any point
in blasting with some high voltage to vaporize whatever is bridging, for
a known unreliable/short-term spare. I'm aware that a valve with leaky C
to H, then running the valve with 10 or 12V on the heaters insted of
6.3V so they glow like bulbs for a few seconds, will knock back the
bridging deposit for a few months or even years.

Used to do that with a TV CRT rejuvenator. It had a specific function to
remove shorts. Sometimes worked, sometimes didn't.

 

[N_Cook]

Used to do that with a TV CRT rejuvenator. It had a specific function to
remove shorts. Sometimes worked, sometimes didn't.

Same here. I still have it and use it about once every couple of
years, now on monitors rather than tv crt's.


&&&&&&&

Any idea what is causing this A/G resistance? Nothing to loose, I will blast
it with some volts. But preliminaries I've seriously banged the envelope and
heated it with hot air and the resistance has hardly moved from 8.7K ohm.
C/H leakage I've never seen below about 100K IIRC and was highly variable on
knocking the envelope.

 

[JW]

Ack! When did Caputo start doing that?

 

[N_Cook]

60V supply over A-G, dropped the resistance to 4.6K . Tried on a 500V
Megger, not expecting to do much as only battery powered. Small white flash
from inside and ohmage shot up to over 200M. Testing on valve tester and
checks out fine