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 Post subject: 1B3 GT TEST
PostPosted: Jan Mon 16, 2023 8:06 pm 
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Location: Sylvania OH 43560
Hi All,

I am servicing a 630ts and basic chking over, tubes and such. I use my
old Heathkit TC-2, and it says expect reading of 26 for good tube.
My reading was nil. The meter stayed in the center. I think I set it up correctly.
My question is about what to expect on the meter?? The set is in the recap
and clean phase, and I have not been able to power up yet. The 6bg6 and other tubes in
hv cage were all good.
thanks


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 Post subject: Re: 1B3 GT TEST
PostPosted: Jan Mon 16, 2023 8:46 pm 
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Location: Latham NY 12110
Filament could be burnt out.


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 Post subject: Re: 1B3 GT TEST
PostPosted: Jan Mon 16, 2023 10:22 pm 
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Location: Minneapolis, Mn
See page 21 of your manual for the instructions for testing the filament. Keep in mind those high voltage rectifiers can test good and not work properly.

DM


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 Post subject: Re: 1B3 GT TEST
PostPosted: Jan Wed 18, 2023 3:36 pm 
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Location: Floral Park, New York
Something doesn't sound right. The TC-2 has a slide switch marked "Line Adjust/Tube Test." If you have no tube in the tester it will let you set the line voltage but when you set it to "Tube Test" the meter pointer should drop to 0. That is your first check that everything is wired correctly (TC-2 was a kit, so there's no guarantee it was) and you do not have any conflicting settings.

Then if you plug the tube in but leave the plate cap off, the filament should light if it is good but the meter should remain at 0. The filament will be extremely dim and hard to see unless you darken the room and look underneath the plate cylinder. The tube only has two connections in its base--pins 2 and 7--so there should be no surprises there. You can test the filament with an ohmmeter from 2 to 7, this should be a low number perhaps a few ohms. There should be no connection (infinite resistance) to any other pin or to the plate cap.

If the tube is rectifying you should get deflection when the plate cap is connected and the tester switch is set to "Tube Test" with all other switches and controls properly set up. One little "oh by the way." The 1B3 has no cathode, just a filament. As a consequence it is more or less "instant on" with no warm-up time. So if the tube just happens to have the right emission to drive the meter mid-scale it will look like nothing changes when you switch from "Line Adjust" to "Tube Test."

Another "oh by the way." In addition to weak and burned-out filaments, 1B3 and similar TV high voltage rectifiers seem to have a habit of going gassy. If that happens a tester like the TC-2 will not show it up; it only applies about 30 volts to the tube so the gas might not ionize. But at 15-kV in a TV high voltage cage you'll see lots of blue or purple glow in the tube which should not be there. A tube tester only tells you whether or not a HV rectifier tube stands some chance of working, not that it actually will work. In later TVs with HV cages that cannot be operated without the covers closed you have to feel the tube after it has been on a while and after the CRT anode has been grounded to prevent shock due to static discharge. [Note added later Chas' comment below: this must be done with the set powered off, all capacitors discharged, and the CRT anode or ultor grounded. Never go in the HV cage of a TV while it is operating. Nothing good can come of it for you or the TV.] A good 1B3 or the like will run warm to the touch but not real hot; if it is gassy it will get hotter than you can comfortably touch.

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Last edited by Chris108 on Jan Wed 18, 2023 5:41 pm, edited 2 times in total.

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 Post subject: Re: 1B3 GT TEST
PostPosted: Jan Wed 18, 2023 3:55 pm 
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Never, ever touch a HV rectifier under full set operation. Do not get within 3" of it :shock: Same applies for the Horizontal output, even the damper can be risky.

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 Post subject: Re: 1B3 GT TEST
PostPosted: Jan Thu 19, 2023 2:07 pm 
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It leaves a little burn mark as I recall. Hitting a 25kv pic tube HV leaves a lasting memory :shock:


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 Post subject: Re: 1B3 GT TEST
PostPosted: Jan Fri 20, 2023 1:28 am 
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They don’t call it a flyback for nothing :D

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People may not remember how fast you did a job, but they will remember how well you did it.


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 Post subject: Re: 1B3 GT TEST
PostPosted: Jan Fri 20, 2023 7:03 am 
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Joined: Dec Sat 28, 2019 3:18 pm
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Location: Corinth, TX, USA
I'll say. Back in the '70s, I was working HAWK Fire Control. The Fire Control van had 4 large CRTs, each powered by a HVPS, 14 kv at about 2 ma, consisting of a transformer, 1B3, and a small capacitor in a protective cage.

One of my coworkers got a little klutzy working on one. The muscle contractions threw him back against the back wall of a mobile team shop.

John


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 Post subject: Re: 1B3 GT TEST
PostPosted: Jan Sat 21, 2023 9:26 pm 
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Location: Quebec, Canada
Back in my day, we used to arc the HV lead to the chassis to check the horizontal section for operation.
Most of us also smoked at least a pack a day, didn't wear seat belts and guzzled enough hard stuff to give Dean Martin a case of the shakes. Still here! Not in great shape, but still here 8)


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 Post subject: Re: 1B3 GT TEST
PostPosted: Jan Mon 23, 2023 1:04 am 
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Location: Phila., PA 19115
arts wrote:
Back in my day, we used to arc the HV lead to the chassis to check the horizontal section for operation.
Most of us also smoked at least a pack a day, didn't wear seat belts and guzzled enough hard stuff to give Dean Martin a case of the shakes. Still here! Not in great shape, but still here 8)


Also played with mercury and stayed outside for hours with no adult supervision. :D

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 Post subject: Re: 1B3 GT TEST
PostPosted: Jan Mon 23, 2023 6:16 pm 
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Location: Sylvania OH 43560
Great Input...
I will revisit test.. and ohms chk.

thanks
jb


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 Post subject: Re: 1B3 GT TEST
PostPosted: Jan Wed 25, 2023 3:07 am 
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I think that most of us who learned TV repair in the old days have been "bitten" As a very young teenager, working on an early split chassis Philco, I quickly learned that the plate of a 6CD6 bites!

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