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 Post subject: Corona
PostPosted: Mar Mon 09, 2020 3:51 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 2013
Location: Waukegan, IL
Can the horizontal output tube have internal corona arching? I can hear the corona noise, but i cant see any purple glow around the flyback or HV rectifer in a darkened room. The only thing i can think of is the output tube. The tube has the characteristic blue glow of output tubes, but thats not corona.

I even applied corona dop to the fly where the lead exits to the hv rectifer as the insualtion was old and flakey.

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Tony Pignaloni


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 Post subject: Re: Corona
PostPosted: Mar Mon 09, 2020 4:11 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 2033
Location: Lafayette, CO
Keep looking.....corona may only happen around the outer edge of the fly or at the base of the 1B3. Craig


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 Post subject: Re: Corona
PostPosted: Mar Mon 09, 2020 6:21 pm 
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Joined: Nov Thu 11, 2010 6:03 pm
Posts: 1224
Location: Pewaukee, WI
Got another output?...swap the other in and if it is still making that noise it rules out the tube its self.

Corona is best looked for in a dark room....it can be dim enough to get washed out by room light. Another trick is to get a few feet of plastic or rubber aquarium or automotive hose and use it as a Corona stethoscope and find it by location of loudest sound... It's more effective than putting your ear in the cage in that a hose can fit a tighter space and much much safer.


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 Post subject: Re: Corona
PostPosted: Mar Tue 10, 2020 8:58 pm 
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Joined: Mar Tue 03, 2009 11:12 pm
Posts: 1618
Location: Hutchinson KS
Sometimes there is a resistor in series with the 2nd anode mounted under the rectifier tube socket that has been known to open up and high voltage arces across the resistor.


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 Post subject: Re: Corona
PostPosted: Mar Wed 11, 2020 3:58 pm 
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Joined: Apr Sat 06, 2013 2:18 pm
Posts: 521
Location: New Hampshire
Do you smell ozone ??


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 Post subject: Re: Corona
PostPosted: Mar Sat 14, 2020 5:03 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1668
Location: Phoenix, Arizona
Corona is usually a faint blue glow around high voltage, sharp points, plate cap of H Out tube, 1B3.
Sometimes the flyback will make little Arcing sounds.

And then there is that virus.

Jim


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 Post subject: Re: Corona
PostPosted: Mar Sun 15, 2020 11:37 am 
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Joined: May Sun 07, 2017 11:35 am
Posts: 840
Location: Belrose, NSW, Australia
You are going to hear a lot more about that virus, COVID 19. Wash your hands and keep 1.5 metres away from anybody else! If you don't want to become a statistic yourself that is. My source for this information is impeccable. The US has a MAJOR problem looming.

Hor OP tubes can develop an effect that sounds like corona. But it this happens you will see jagged edges on the sides of the raster.

We saw a lot of this in the early 1970's when a major tube maker moved their plant interstate. This meant they had to use natural gas instead of coal gas. Glass started cracking near the base after a few weeks service. They added more lead into the glass to fix it, then the arcing problem started. This all happened right at the end of tube production. The solution was to rebrand the opposition's product and later to import them from Japan instead.

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Wax, paper, bitumen, cotton, high voltages - what could possibly go wrong?


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