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Ur tv the high voltage it dead,the FBT,the flyback transformer.The big black block of plastic with a red wire with a black cap that hook up to the CRT(tv tube) is dead.The FBT,flyback transformer needed it to be replaced to solved this problems.Call the shops,take estimates for the best deal to do the repair.This is one of the main part of the tv to put HV in CRT(tube tv).It pretty hard to find this FBT these day,because of the discontinue of making of Amalog tvs.
It's not the picture tube(especially if image was good b4 it went dead). The high pitch noise is the power supply whinning because it's shorted or overloaded. I just fixed one of these sets - replaced the horiz. o/p transistor and flyback estimate around $120.00-$160.00
WOW...had a high pitch noise, came and went...got worse as time wore on. Would shut off the set, times it cleared times it didn't. Warranty folks set out a TV repairman--said he had worked for RCA exclusively for years...anyway, explained that the 1k hertz noise was a known issue with the HD56W58 and that RCA’s published fix was "nail polish" applied on some board, had something to due with power and vibration...long story "presto" noise gone...but after 6 or so months we began to hear it again—say it ain’t so, but yes the high pitch was back. Same repairman, this time bigger problem...along with noise, the network card is broke and Fry’s Electronics (Irving, TX—hear that Corporate HQ at San Jose…your Irving store needs to be leased in and tote the company line...where's the customer satisfaction???) is balking at a “equal” replacement, they see it as take the less than equal product or get store credit…good luck & wish me luck with the equal replacement they tout when pushing the warranty.
the high pitch squeal indicates shorted component/s. the transformer goes hot co'z its being overloaded by the shorted component, it too could be the one creating the squeal!!
if you have experience with electronic troubleshooting, try to test some of the components particularly on the secondary part of the transformer. Be careful and make sure the TV set is unplugged. test for shorted diodes and transistors, if you're in doubt of your readings try to desoldering one leg of the diode then proceed with the testing/measuring. replace any of the bad components you find exactly with same part number or replacements with the same rating.
spend more time on it resoldering some other cold soldered components.
What you are hearing is the discharge of high voltage which if it hasn't already failed, will fail if allowed to repeat too often.
The only thing you might try after unplugging the set for a minimum of 24 hours, is to remove the back shell (shouldn't be more than 8-10 screws around the perimeter and perhaps one or two around the connector cutout) and with a clean paintbrush and a vacuum cleaner with the nozzle held close to the work area, brush the CRT (picture tube) free as possible of accumulated dust, paying particular attention to the area around the large rubber cap with a cable leading to the circuit board.
I can't stress enough that the set must be ignored to allow the 25,000 plus volts that are present on the CRT when operating are given a chance to 'bleed off.'
This voltage doesn't often kill anyone since it is a short-term discharge with the set off but I have seen it punch a hole through a thumb.
If you are lucky, the horizontal circuit is not in its death throes but only discharging through a layer of typical household crud.
Unfortunately, this will not likely help you and you will require a tech to locate the problem.
Good luck finding one that isn't dead or retired yet; we are dwindling.
The high pitch squeal you hear is usually caused by a coil vibrating, normally in the horizontal circuit. I've also seen the ferrite bead on the horizontal output transistor do this, but, it is rare.
I normally will repair this by finding the coil and "tightening" it.
To tighten a coil, technicians use different chemicals, such as, a hot glue gun, rubber silicone or even finger nail polish.
I will find the coil that screams by starting with the usual suspects and using a wooden dowel, barely touch the coil and if the pitch of the noise changes, then, thats the coil that needs repaired.
If you do not know your way around the inside of a television, I never recommend you do so, since, this procedure must be done with the set turned on and you poke your hands around the inside of the set by the high voltage circuit.
Hope this helps your decision.