Dumb TV question
What is the purpose of the small neon bulb by the flyback on older TVs? (I haven't noticed it in any modern tvs.)
Someone asked me that the other day and I couldn't answer! Seems like I used to know (I'm an old-timer) but can't remember. Thanks. |
Dumb TV question
"oldfogie" wrote in message .. . What is the purpose of the small neon bulb by the flyback on older TVs? (I haven't noticed it in any modern tvs.) A voltage clipper? Neon lamps have very high resistance and then drop to a low resistance when the gas ionizes. About 60 volts, I think. |
Dumb TV question
oldfogie wrote:
What is the purpose of the small neon bulb by the flyback on older TVs? (I haven't noticed it in any modern tvs.) Someone asked me that the other day and I couldn't answer! Seems like I used to know (I'm an old-timer) but can't remember. Thanks. 50-100 volt spike clamp?? |
Dumb TV question
oldfogie wrote:
What is the purpose of the small neon bulb by the flyback on older TVs? (I haven't noticed it in any modern tvs.) Someone asked me that the other day and I couldn't answer! Seems like I used to know (I'm an old-timer) but can't remember. Thanks. Could be a voltage reference (~60 - 90 V), voltage drop or translation, a hysteresis element in a multivibrator, clamp or even indicator of some circuit's status. Regards, Michael |
Dumb TV question
Are you sure it is really a neon bulb? I'm thinking it is possibly a high
voltage spark gap which serves as overvoltage protection... Just my thoughts. Without seeing it it would be hard to say for sure. Bob "oldfogie" wrote in message .. . What is the purpose of the small neon bulb by the flyback on older TVs? (I haven't noticed it in any modern tvs.) Someone asked me that the other day and I couldn't answer! Seems like I used to know (I'm an old-timer) but can't remember. Thanks. |
Dumb TV question
On Jan 28, 6:28�pm, "Bob Shuman" wrote:
Are you sure it is really a neon bulb? � I'm thinking it is possibly a high voltage spark gap which serves as overvoltage protection... �Just my thoughts. �Without seeing it it would be hard to say for sure. � � Bob "oldfogie" wrote in message .. . What is the purpose of the small neon bulb by the flyback on older TVs? (I haven't noticed it in any modern tvs.) Someone asked me that the other day and I couldn't answer! Seems like I used to know (I'm an old-timer) but can't remember. Thanks. I'll bet it's a solid state GE from the early 1970s. They included the bulb as a high-voltage indicator. This was to deter arcing with a screwdriver as a test. |
Dumb TV question
Yes, I'm sure, was a small glass neon bulb soldered to chassis.
I looked through a good many old Sams folders, back into the '70s & '80s but never found a neon bulb in one. Problem is, just because it was near the fly doesn't have to mean it was in the fly circuit. So it must have been in some other circuit. I think it was for spike protection, for whatever circuit it was in. I'm ready to just forget it, not important. Thanks to all for replies! "Bob Shuman" wrote in message ... Are you sure it is really a neon bulb? I'm thinking it is possibly a high voltage spark gap which serves as overvoltage protection... Just my thoughts. Without seeing it it would be hard to say for sure. Bob "oldfogie" wrote in message .. . What is the purpose of the small neon bulb by the flyback on older TVs? (I haven't noticed it in any modern tvs.) Someone asked me that the other day and I couldn't answer! Seems like I used to know (I'm an old-timer) but can't remember. Thanks. |
Dumb TV question
A real neon bulb? I wish I owned a million of them, I love neon
lights/neon signs.I own an old broken neon NO VACANCY sign I bought at the Goodwill store years ago.It was broken when I bought it.I like it anyway.I think it dates back to the 1940s or 1950s.Nothing beats neon lights and neon signs. cuhulin |
Dumb TV question
I think it was used as a high-voltage clipper... sort of a high-voltage
zener diode. During normal operation it's never supposed to light up. I often saw those on neck boards of old monochrome video monitors. Only once did I ever see one light up and that was due to picture tube failure (the precise details of which I can't remember now). The firing voltage of neon bulbs is pretty high... at least 50 volts, some go as high as 90 volts. BTW: If the bulb is placed across DC, only one of the interior electrodes will light up. If the bulb is placed across AC, then both internal electrodes will light up. |
Dumb TV question
"oldfogie" wrote in message ... Yes, I'm sure, was a small glass neon bulb soldered to chassis. I looked through a good many old Sams folders, back into the '70s & '80s but never found a neon bulb in one. Problem is, just because it was near the fly doesn't have to mean it was in the fly circuit. So it must have been in some other circuit. I think it was for spike protection, for whatever circuit it was in. I'm ready to just forget it, not important. Thanks to all for replies! If it was a true neon bulb, then it wouldn't actually need to be connected into any circuitry in order to light up as an indicator of flyback activity. Most gas filled tubes will light in mid air if they are in close enough proximity to a flyback tranny. Back when I was an apprentice, like 35 years ago, the guy that I worked under in a TV workshop, used to keep a short thin flourescent tube on his bench. He used this to test for horizontal output stage activity, simply by waving it around the FB tranny. As I recall, he used to reckon that he could tell a lot about how that stage was working, when he had a lack of picture fault, just by the 'way' in which his little tube lit up. Most of the similar 'bulbs' that I've seen on CRT base connector boards, have been gas-filled spark gaps. I seem to recall that they used to put argon in them, and when they went off as a result of an inter-electrode short in the tube, they lit up white, rather than the orange glow of a neon. Arfa |
Dumb TV question
On Tue, 29 Jan 2008 13:46:44 GMT, "Arfa Daily"
wrote: If it was a true neon bulb, then it wouldn't actually need to be connected into any circuitry in order to light up as an indicator of flyback activity. Most gas filled tubes will light in mid air if they are in close enough proximity to a flyback tranny. Back when I was an apprentice, like 35 years ago, the guy that I worked under in a TV workshop, used to keep a short thin flourescent tube on his bench. He used this to test for horizontal output stage activity, simply by waving it around the FB tranny. As I recall, he used to reckon that he could tell a lot about how that stage was working, when he had a lack of picture fault, just by the 'way' in which his little tube lit up. Years ago, we'd just tape or glue a neon bulb on either a dowel or a pencil. Then someone realized that pencil lead conducts and the dowel method became much more popular! |
Dumb TV question
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Dumb TV question
Assuming the HV supply is still good, you should have it rebuilt. Neon signmakers are plentiful, generally do good worrk, and can duplicate any tube you bring them. Just a thought. Even if it weren't, used neon transformers are cheap. I haven't heard anything but incoherent rantings from that guy though, I dunno what he's doing on this group. Nothing he posts makes any sense, or has anything to do with electronics repair. |
Dumb TV question
wrote in message ...
Which reminds me. I have an old neon bulb nightlight. This thing is confused and retarded. If the room is dark, it does not light. But when I flip on the ceiling lights in the room, or point a flashlight at it, the neon lights up... I think it's just plain old, but I leave it there just because it's a conversation piece. Believe it or not, this is more or less normal for an old neon bulb. Ambient light knocks electrons off the neon atoms in the bulb, _lowering_ the threshold voltage. This bulb has aged to the point where the line voltage isn't high enough to light it _until_ room light or a flashlight "kicks butt" on them-there outer-orbital 'lectrons. |
Dumb TV question
My old NO VACANCY neon sign is an old metal box, the old brown paint on
the box is very faded.The neon glass tubes, some parts of the glass tubes are completly broken away, missing.The box still has the old high voltage power thingy in it.I don't think there is anybody in my local city area who builds/repairs old neon signs.I only hang onto it because it is very old and I like to collect all kinds of very old things.The Postman Always Rings Twice old movie.That poor cat got zapped on that neon sign. cuhulin |
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someguy@ invalid.com wrote:
I have an old neon bulb nightlight. This thing is confused and retarded. If the room is dark, it does not light. But when I flip on the ceiling lights in the room, or point a flashlight at it, the neon lights up... I think it's just plain old, William Sommerwerck wrote WITHOUT ATTRIBUTION TO THE PREVIOUS POSTER: Believe it or not, this is more or less normal for an old neon bulb. Yup. In the '60s, electronic organs used neons in their percussion circuits (e.g. a Xylophone tab). Incandescents were positioned inside the unit near the neons so that NE-2s were "biased". When someone said his precussion stopped working, you made sure your stock of mini incandescents was up to snuff. |
Dumb TV question
Arfa Daily wrote:
Back when I was an apprentice, like 35 years ago, the guy that I worked under in a TV workshop, used to keep a short thin flourescent tube on his bench. He used this to test for horizontal output stage activity, simply by waving it around the FB tranny[...] Old tricks are so cool. Most of the similar 'bulbs' that I've seen on CRT base connector boards, have been gas-filled spark gaps. I seem to recall that they used to put argon in them, and when they went off as a result of an inter-electrode short in the tube, they lit up white, rather than the orange glow of a neon. Well, Argon would be the cheapest --but the Argon stuff I've seen glows purple. Maybe those are a different gas--or a gas mixture. http://www.google.com/search?q=cache...righter.orange |
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Dumb TV question
"James Sweet" wrote in message news:%8Nnj.3854$1f.2860@trndny02... "Tim" wrote in message ... In article , says... My old NO VACANCY neon sign is an old metal box, the old brown paint on the box is very faded.The neon glass tubes, some parts of the glass tubes are completly broken away, missing.The box still has the old high voltage power thingy in it.I don't think there is anybody in my local city area who builds/repairs old neon signs.I only hang onto it because it is very old and I like to collect all kinds of very old things.The Postman Always Rings Twice old movie.That poor cat got zapped on that neon sign. cuhulin You could always use those Cold Cathode light ropes they sell for computer case modding. They could bring the neon look back to life, with no HV problems to deal with. - Tim - Or just send the glass out to have it fixed properly. I dunno how it's possible to live to far from a neon shop, there's lots of mom & pop joints still spread around the country. The craft nearly died out for a while, but in the last couple decades there's been somewhat of a revival. Once have the sign box with the transformer, it's not terribly expensive to have new units made for a simple sign like that. There's LED "neon" out these days, but nothing comes close to the real thing, it just doesn't look right. Yup ! 'Neon' tubework has a look all of its own. When I first went to Vegas probably 20 odd years ago, it was all neon. Now, with a few exceptions like the main signage at Flamingo, and one or two machine banks on the casino floor, the Strip is now predominantly lit by LEDs and LED giant screen TVs. There's still some original-style neon tubework downtown at the Golden Nugget and so on, but not a lot any more. The neon had a much more 'organic' feel about it, I think. Kinda like the difference between film and video. Still very pretty there, and unlike anywhere else on earth, but not quite as 'warm' feeling as in the old days ... Arfa |
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"JeffM" wrote in message ... Arfa Daily wrote: Back when I was an apprentice, like 35 years ago, the guy that I worked under in a TV workshop, used to keep a short thin flourescent tube on his bench. He used this to test for horizontal output stage activity, simply by waving it around the FB tranny[...] Old tricks are so cool. Most of the similar 'bulbs' that I've seen on CRT base connector boards, have been gas-filled spark gaps. I seem to recall that they used to put argon in them, and when they went off as a result of an inter-electrode short in the tube, they lit up white, rather than the orange glow of a neon. Well, Argon would be the cheapest --but the Argon stuff I've seen glows purple. Maybe those are a different gas--or a gas mixture. You could very well be right - it's been a long time since I was commercially involved in TV repair and doing it all day every day. I'm pretty sure that they were argon filled, and I had this recollection of the discharge being white or blue/white, but the old memory is not what it was any more. Hell, I have trouble remembering what I had for breakfast these days - well, not quite, but you know what I mean ! Arfa |
Dumb TV question
On Jan 28, 5:56*pm, "Charles" wrote:
"oldfogie" wrote in message .. . What is the purpose of the small neon bulb by the flyback on older TVs? (I haven't noticed it in any modern tvs.) A voltage clipper? *Neon lamps have very high resistance and then drop to a low resistance when the gas ionizes. *About 60 volts, I think. Zenith liked to use them on their mid 60's - early 70's tube sets. They seemed to use them for several purposes in the horiz. sweep circuit. I remember some 16" - 19" B&W portables where the neon bulb lit up constantly when the set was on. I have a 25CC50 chassis color set that uses two in series in the HV regulator circuit. They light for a few seconds after the horiz. sweep starts then go out once the HV comes up. Mike |
Dumb TV question
James Sweet wrote:
Assuming the HV supply is still good, you should have it rebuilt. Neon signmakers are plentiful, generally do good worrk, and can duplicate any tube you bring them. Just a thought. Even if it weren't, used neon transformers are cheap. I haven't heard anything but incoherent rantings from that guy though, I dunno what he's doing on this group. Nothing he posts makes any sense, or has anything to do with electronics repair. He trolls a lot of groups. Take a look at his rantings on news:rec.radio.shortwave if you need proof. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida |
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Michael A. Terrell wrote:
James Sweet wrote: Assuming the HV supply is still good, you should have it rebuilt. Neon signmakers are plentiful, generally do good worrk, and can duplicate any tube you bring them. Just a thought. Even if it weren't, used neon transformers are cheap. I haven't heard anything but incoherent rantings from that guy though, I dunno what he's doing on this group. Nothing he posts makes any sense, or has anything to do with electronics repair. He trolls a lot of groups. Take a look at his rantings on news:rec.radio.shortwave if you need proof. I think he's fairly innocuous; but it does appear that he's often well-lubricated when he pushes the 'send' button. Basically, I think he's just lonely...but annoying at times. jak |
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jakdedert wrote:
I think he's fairly innocuous; but it does appear that he's often well-lubricated when he pushes the 'send' button. Basically, I think he's just lonely...but annoying at times. If he's lonely, he needs to find someplace to do volunteer work. Find a place where he can interact with others, rather than spend his time bothering people online. Life is too short alredy, so live it while you can. :) -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida |
Dumb TV question
"Michael A. Terrell" wrote in message
... jakdedert wrote: I think he's fairly innocuous; but it does appear that he's often well-lubricated when he pushes the 'send' button. Basically, I think he's just lonely...but annoying at times. If he's lonely, he needs to find someplace to do volunteer work. Find a place where he can interact with others, rather than spend his time bothering people online. I wish him luck finding it. In the Fall of 2004 I was unemployed and looking for a way to usefully spend my time (if only to lighten my depression). When I applied to the King County Library System to tutor kids in math and science, I was immediately rejected as "unqualified". Hell, I was accepted by Caltech, MIT, and Case. I haven't looked for volunteer work since. |
Dumb TV question
William Sommerwerck wrote:
"Michael A. Terrell" wrote in message ... jakdedert wrote: I think he's fairly innocuous; but it does appear that he's often well-lubricated when he pushes the 'send' button. Basically, I think he's just lonely...but annoying at times. If he's lonely, he needs to find someplace to do volunteer work. Find a place where he can interact with others, rather than spend his time bothering people online. I wish him luck finding it. In the Fall of 2004 I was unemployed and looking for a way to usefully spend my time (if only to lighten my depression). When I applied to the King County Library System to tutor kids in math and science, I was immediately rejected as "unqualified". Some only accept retired teachers, for some reason. Hell, I was accepted by Caltech, MIT, and Case. I haven't looked for volunteer work since. There are a lot of retirement homes around here that welcome people to spend time with the residents. Non profit thrift stores and various clubs always need help. A friend has had to depend on community service workers lately for his thrift store. The Humane Society, Habitat for Humanity and any VA clinic or hospital needs volunteers. The local VA clinics are all desperate for volunteer drivers, to drive the eight passenger DAV vans from local clinics to the Gainsville VA hospital. The local United Way has a list of about 100 organizations needing help. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida |
Dumb TV question
"Michael A. Terrell"
wrote in message ... There are a lot of retirement homes around here that welcome people to spend time with the residents. There's a hospital not far from me, and I've considered going in. The problem is that I'm not quite yet ready to listen to people talk on ad-infinitum. I appreciate your suggestions, though, and will keep them in mind. At the moment, my car is not running reliably. |
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