56" RCA projection TV (FLYBACK related problem)


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56" RCA projection TV (FLYBACK related problem)

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Haitham
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Jan 16, 2007, 1:11 PM

Post #1 of 7 (344 views)
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56" RCA projection TV (FLYBACK related problem)	Can't Post

Hello!!

I just replaced the FLYBACK transformer (part # 239111) on my 56" RCA rear projection TV model P52921 (chassis CTC195M). I believe the new FLYBACK is not original. Anyhow, after replacement the TV powered up and initially the picture looked fine. However, everytime the unit is powered up there is a noise coming from the back that lasted for 3-4 seconds then it disappears. The TV worked well with the exception of the noise and a slight blurr at the very right edge of the screen. The TV worked in that manner for about 7 days until today it did not power up as it did before replacing the FLYBACK.

Without any testing and with those two clues (the noise and picture blurr) can someone help me understand what might the problem be?

It could be anyone of these: The new FLYBACK, the HOT blew, Driver and HOT base circuit components, the LV regulator, or maybe bad soldering to the new FLYBACK.

Any good ideas?

Thanks!

(This post was edited by Haitham on Jan 16, 2007, 1:14 PM)

Haitham
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Jan 18, 2007, 1:19 AM

Post #2 of 7 (332 views)
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Re: [Haitham] 56" RCA projection TV (FLYBACK related problem) [In reply to]	Can't Post

I was able to narrow the problem down a bit just need a few information. I need to know both the location numbers and part numbers for those two HOTs (the horizontal output transistor and trnasformer). If you can provide me with this information I will be very thankful!

TV guy 1966
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Jan 18, 2007, 10:23 PM

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Re: [Haitham] 56" RCA projection TV (FLYBACK related problem) [In reply to]	Can't Post

Well I have seen my share of these. The noise your hear could be the Red high voltage anode not setted correctly inside your new transformer. If you can pull the anode out of the transformer and look at the end and see the center pin shoved up next to the base of the wire itself that is the cause of your noise, but that is not the cause of the unit being dead again. First check your work second place your ear next to the chassis and turn on the unit. If you hear any noise what so ever like a small zip that means your getting turn on and the unit is going into a over current shutdown. Your new generic transformer is defective get a new one. The RCA one is still available I just got one last week. I have had problems with the generic ones but it took serveral months for it to shoot its wad again.If the HOT was shorted you would here a chirpping sound from the switch mode power supply. If no zip noise take a meter and check to see if you have 130vdc of B+ on the collector of the HOT without turning it on (standby only). If your B+ is not there your problem is from the line cord to the secondary section in the switch mode power supply. This shouldn't be the case. I have never had a switch mode power supply issure with this chassis before or unless the problem was self inflicted. Your problem is with the new transformer or the best senareo is there is a problem with your work. Play close attension to the pads you have solderd on and make shure there not broke free from the foil paths there attached too. Good Luck.

Haitham
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Jan 19, 2007, 1:22 AM

Post #4 of 7 (323 views)
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Re: [TV guy 1966] 56" RCA projection TV (FLYBACK related problem) [In reply to]	Can't Post

You seem to have a considerable knowledge and experience. When I was replacing the FLYBACK I could not get the high voltage red wire out from either end (The old FLYBACK or the CRT end) so I decided to cut it and reconnect with metal connectors. Do you think that is where the leak is coming from.
Also, I want to ask you about all the components that could make noise other than the FLYBACK? For example, would any of the HOT or horizontal driver make any noise?
Thanks a lot for sharing these valiable tips!!!

TV guy 1966
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Jan 22, 2007, 12:10 AM

Post #5 of 7 (311 views)
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Re: [Haitham] 56" RCA projection TV (FLYBACK related problem) [In reply to]	Can't Post

That is a good chance that's where the noise is comming from. There is 30 thousand volts on that lead and if its not isulated REAL GOOD just not a couple wraps of electrical tape it will spit Hight Voltage to ground, It will sound like a hissing noise. The other noise your talking about is a ringing noise. It will sound high pitched depending on freq. The cause could be your new transformer or the horz. linarity coil next to the horz.output transistor. You can just take some rubber silicon and caulk the shit out of it to stop it from ringing. There is a freq. that drives the high voltage and deflection and some times you may here a oscilation from those componets. Back to your transformer, you can grab and stabllize the transformer and carfully pull the lead out. Look and see the lead dress on the wire you pulled out and cut back to your splicing and insert it back into the transformer. Depending how far you spliced back you may not have anough length. You transformer you bought may have came with some new wire with a anode cup attached. Cut off the cup and use that wire, it may be long anough. Did you get the power back? good luck.

Larry E
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Jan 23, 2007, 9:59 PM

Post #6 of 7 (301 views)
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Re: [TV guy 1966] 56" RCA projection TV (FLYBACK related problem) [In reply to]	Can't Post

I`m amazed you haven`t killed yourself or seriously hurt yourself by splicing that anode lead with metal clips !!! Call a tech before you get killed, you have absolutely no idea what the hell your doing, it amazes me what you laypersons will do to save a buck !

mllorlando
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Jan 26, 2007, 4:42 PM

Post #7 of 7 (278 views)
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Re: [Haitham] 56" RCA projection TV (FLYBACK related problem) [In reply to]	Can't Post

I to have a 56 Rca Model HD56w58. Just had the thing for a year. It shuts down intermittently for 2 to 6 hours since Oct.

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