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TV Back-light Spark Gap?

###No I didn't - the quoted text has been mishandled.

###It wasn't me said that.

Only on starting.

Once struck, the voltage drops (a few hundred), and the PSU goes into constant current mode.

###Don't quote me on this - but I read somewhere the disc ceramic series coupling capacitors provide a high Xc compared to the apparent resistance of the ionised tube (to all intents & purposes constant current) - most TV backlight inverters have large copper pads on opposing sides of the PCB to form the series coupling capacitors, so the capacitance isn't large.

###If you'd quoted my text - I said around 1200V to strike, about half that ionised.

###In another post I mention HR (of excellent pattern flyback transformer fame) CCFL backlight inverters, the datasheet I've read gave the figures I quoted above - if the datasheet for the particular TV can be found; the exact values can be nailed to the bull's eye.

Reply to
Ian Field
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It must be scary to drive there, with some fraction of the motorists driving around without steering wheels.

***They fit those tiny racing steering wheels - so the escaped convicts can drive with handcuffs on.
Reply to
Ian Field

On examination, I find you are correct.

If you'd used proper quotation conventions, instead of hashes and asterisks, I might have attributed it correctly.

Usenet convention is > (greater than) for quoted text. Has been for at least twenty years.

--
"For a successful technology, reality must take precedence 
over public relations, for nature cannot be fooled."
                                       (Richard Feynman)
Reply to
Fred Abse

Update: While on a phone call I noted that the muted TV has no pop, and the screen never did "blink", so the popping noise must have another cause. ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.
Reply to
Jim Thompson

Well you're a semi engineer, must be shot noise ! ;)

Jamie

Reply to
Jamie

Welcome to the wonderful world of consumer electronics troubleshooting. Could you disclose the Philips model number? You'll get to earn your new 55" flat screen TV by first playing detective.

Find a portable AM radio. Tune it to a blank place on the AM dial so that you hear only hiss or maybe a really weak station. Put it near the TV. Do you also hear a popping noise on the AM radio? If so, it's probably coming from internal arcing somewhere inside the TV. If not, it's something else.

Duz the popping sound happen on all channels or only one channel? Is the TV setup for OTA (over the air) TV, or are you using a cable, satellite, or screaming media box? If you're using a box, turn it off and see if the popping sounds go away. It might be coming from a converter, not from the TV. If you're getting your audio from a converter box, try running the audio output to something else, like a hi-fi or headphone to determine its origin.

Duz the TV have different input modes, such as composite video, HDMI, DVI, component video, VGA, or S-video? Try some of these modes and see the popping sounds are in all the modes or just some of them.

The basic idea is to isolate sections of the TV and attached components. Then, to replace or bypass sections until the culprit can be determined.

--
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558
Reply to
Jeff Liebermann

Borrowing a line from "The Sting", I know how to get drunk... and debug circuits... I grew up in a radio and TV repair shop.

I was just looking for easy answers. At my income level toss and replace is often the least costly. ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.
Reply to
Jim Thompson

If its in the audio, perhaps you've got a cap in there that's going bad. Look for electrolytics that are swelling.

--
Paul Hovnanian     mailto:Paul@Hovnanian.com
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Reply to
Paul Hovnanian P.E.

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