Q For Old-School TV Repairman

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sleddriver

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My 1990 JVC 36" TV began temp. arcing while the air-cond was out. Temp & indoor humidity were quite high. It's never arced previously. Eventually it refused to light. Given its size, I'm guessing the HV side is around 36kV. It's been awhile since I pulled the rear cover and cleaned the fine black dirt that accumulates due to HV.

I do still hear it 'click' with the remote however no red ON light as usual. May have also fried something in that ckt.

What's the best method to check a flyback without a HV probe?
Ditto for discharging the tube.
 
You're going to have to check the nursing homes for someone that worked on those things.
grin.gif
 
Just like a 9v battery, touch the anode lead to your tongue
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The CRT you can discharge by grounding the aonde while it's still attached. Do you have voltage going to the flyback?

Hopefully Papa Bear will chime in with the correct answers.
 
Originally Posted By: hatt
You're going to have to check the nursing homes for someone that worked on those things.
grin.gif



LOL! And my dad thought he was old still having a rotary phone
smile.gif
 
My dad open'd up our tube tv 15 years ago or so as the screen vertical kept moving. He did discharge the tube using alligator clips connected to a flathead screwdriver. I wouldn't do it but the electricity should run down the screwdriver and into the alligator clips.
 
I used to just yank the suction cup looking connector from the tube and use a screwdriver, the way some people discharge capacitors. I worked on a number of CRT TVs back in the day.
 
I remember my dad takeing tubes out out of the tv then going to thrifty drug store. They had a tube testing table. You plugged your tube in and it showed good or bad. If it was bad you bought one from the display under the testing table.
 
Originally Posted By: Chris142
I remember my dad takeing tubes out out of the tv then going to thrifty drug store. They had a tube testing table. You plugged your tube in and it showed good or bad. If it was bad you bought one from the display under the testing table.


That's a while back. TVs were solid state by the early 70's.
 
Originally Posted By: dishdude
Originally Posted By: Chris142
I remember my dad takeing tubes out out of the tv then going to thrifty drug store. They had a tube testing table. You plugged your tube in and it showed good or bad. If it was bad you bought one from the display under the testing table.


That's a while back. TVs were solid state by the early 70's.


Just the new ones were, a fleet of expensive old ones were still in service.

I remember Radio Shack having a tube tester circa 1983!

Kids, these are the origins of the stickers that read

"No user serviceable parts inside" and
"Simulated wood grain"
crackmeup2.gif
The darn woodcutter's union got involved.
 
I bought an older style 27" TV on clearance right around 2009. I wish it would die so I can finally get a flat screen....lol. The last one lasted 24 yrs.
 
Originally Posted By: sleddriver
My 1990 JVC 36" TV began temp. arcing while the air-cond was out. Temp & indoor humidity were quite high. It's never arced previously. Eventually it refused to light. Given its size, I'm guessing the HV side is around 36kV. It's been awhile since I pulled the rear cover and cleaned the fine black dirt that accumulates due to HV.

I do still hear it 'click' with the remote however no red ON light as usual. May have also fried something in that ckt.

What's the best method to check a flyback without a HV probe?
Ditto for discharging the tube.
The horizontal output transistor drives the flyback, the HV transformer that the anode wire goes to. The CRT anode can be discharged with a wire & alligator clips to the metal chassis (if there's any charge left). On many (old) sets the flyback is part of the power supply, the arcing may have taken out the power supply. Why do you want to fix it? Chances of any modules or the flyback being available are pretty slim.
 
I bet the color on that old TV looks bad. The picture quality slowly degrades on tube TV's and it's often unnoticed by the user over the course of many years.
I still have a Sony tube TV(34" widescreen hi-def 1080i) I bought new in 2006.
 
Originally Posted By: 69GTX
I bought an older style 27" TV on clearance right around 2009. I wish it would die so I can finally get a flat screen....lol. The last one lasted 24 yrs.


If you do give in and buy a new TV while this one still operates, if you had any thoughts of selling it ..... don't. I see people listing their old CRTs on Facebook for-sale groups and similar and most are listed something like this:
Quote:
$50, works great. You must pick-up from our home - no deliveries, no meet-ups. I can't help you move it either, it's real heavy.
Most donation places won't even take them anymore.
 
Originally Posted By: 69GTX
I bought an older style 27" TV on clearance right around 2009. I wish it would die so I can finally get a flat screen....lol. The last one lasted 24 yrs.


I wish my flat screens would die. Then I could get a 4k TV. The last tube TV I also got on clearance, but then I got a flat screen and just put it in the dumpster. Had no value even though it was a 32" JVC and this was probably over 5 years ago.
 
Originally Posted By: dishdude
Originally Posted By: Chris142
I remember my dad takeing tubes out out of the tv then going to thrifty drug store. They had a tube testing table. You plugged your tube in and it showed good or bad. If it was bad you bought one from the display under the testing table.


That's a while back. TVs were solid state by the early 70's.
this would have been in the early 80's. They closed that store around 1995 and it was still there till the end.
 
Originally Posted By: Chris142
Originally Posted By: dishdude
Originally Posted By: Chris142
I remember my dad takeing tubes out out of the tv then going to thrifty drug store. They had a tube testing table. You plugged your tube in and it showed good or bad. If it was bad you bought one from the display under the testing table.


That's a while back. TVs were solid state by the early 70's.
this would have been in the early 80's. They closed that store around 1995 and it was still there till the end.


That's pretty cool, I've never seen a tube tester like that.
 
This is a basic hack w/o a probe. A piece of paper should stick to the crt face when energized and you should hear the usual crackle noise as well. To discharge, use an aligator clip lead attached to a flat blade screwdriver and the other end clipped on the grounding braid on the bell of the crt(the negative of the crt). Pop of the suction cup at the anode, hold the screw driver in the anode for 15 seconds.. I wouldn't fix it if it were me.The arcing probably back fed into the circuit. I rarely saw a flyback go bad in a solid state set. When they did there was a pinhole blown out the side and you saw this dried glob of varnish on the side of the flyback.
 
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