help with the poping sound

[jimmy]

I have RCA big screen 60" T.V. 1995 model # p52731wk When I turn it on I see a pic and sound, But after it is on for 2min or less. I hear a poping sound coming from the back of the set. and the pic is not looking to good after i hear the poping sound

[Chris Smith]

Sounds like a cap is failing.<p>The voltage builds up, then shorts and the shunt of excess power CAN do harm to the rest of the system, aside from just destabilizing the circuit. <p>What I do in these cases is use a long plastic tube, flexible or stiff, and open the back cover, keep your hands well clear, and use the tube as a stethoscope to find the bad area. <p>HANDS clear!!! There are voltages back there that can kill.

[haklesup]

There is a good chance you will be able to see the arcing in a darkened room with the back removed. Do you smell any burning or ozone. A failed cap is a very good possibility but there are other causes of arcing as well. <p>The location is the key. If you have already run it in this condition and it has not deteriorated further while you do so then it is probably safe (for the TV) to search for the fault powered up. If it seems to be degrading, you should focus on powered down troubleshooting and use a meter to check every component you can in the HV section especially checking the caps for leakage.<p>Be aware that a partially failed component can suddenly completely fail with no advanced notice. Sometimes this results in the component self destructing in a dramatic way. If you're looking in the back while powered up, use safety glasses even if you aren't putting your hands inside.

[Edd]

MMmmmmm Beeeeeeg Screen Tee Wee<p>.....…but now, being just as inquisitive as……a…….la……Dirty Harry's “I got’s to know”… Whats a “poping” sound ?<p>Being an owner of the same family of RCA BS TV which you mentioned, I have experienced a like failure in the quasi-immediate past,
much in the same manner that you described. The noise exhibits the sharp report of a small firecracker(s) going off in the top left
quadrant of the rear of the set, when being viewed from the rear, along with the lingering fragrant aroma of ozone production.
(Lightning/thunderstorm/ozone……remember ?).<p>Failure analysis revealed the developing of a crazing/crack/pinhole in the Acryl-Buta-Styrene housing of the sets HV divider block.
That device takes the developed voltage from the sets flyback HV transformer and divides it into three separate sources of high voltage
to supply the sets three picture tubes. Initially it was so infrequent that only on very humid days would the air path to the closest
ground connection break down and permit a corona discharge with its accompanying….BANG !. Then, with time and several
arcs, a carbonized conductive surface trail was formed and then the whole block shorted out with other driver parts being
damaged/knocked out simultaneously.<p>Visually, I am assuming you to have seen an accompanying blink of the picture on the disruption of the HV along with asimultaneous
loss of the 7.5 Kv focus source and its blurring effect.
If visual/aural inspection reveals the same problem, that which you will be needing is another RCA (Original Equipment Manufacturer) /replacement HV Block/divider. There are a few different numbers, so work with the 6 digit number on the original
units housing.
Use this picture/source for visual reference only; Click on its photo for a better 2x mag:<p>http://www.moteva.com/shop/customer/home.php?cat=365 <p>If your unit proves to be bad......don’t use the ref’d POS…..get/use the RCA original part only.<p>
73's de Edd
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<p>[ October 22, 2005: Message edited by: Edd Whatley ]</p>