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Re: Testing a IHVT Flyback Transformer to see if is still...
Really, the only test you can do statically is to make sure that there are no open windings. There are some shops that can "ring" the windings to see if they resonate properly, but if you've gone to the trouble to remove the FB, you might as well replace it, especially if you already suspect it to be your problem...accordianman
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I read the other post you made and I don't belive that the flyback transformer has gone , and these models and makes from rca do have some common fixes that are found out by tech's . this problem that you are having can be in the power section , stanby circuit , protection circuit or even a horizontal output IC or some component that is causing the set not to come on . the flyback transformer would need to be tested to determine if it went bad but the power section would need to be tested first because there are different voltages that come out of the primary transformer and they go to different parts of the tv's functions and circuits , also info like what happen when it went out? and or was there a problem with it while watching it before it went out? , this can help to know what section was failing , thus start the testing in that section.
the best thing to do is to call an electronic repair shop to have a teck come out so they can determine the failure for you , as these are pretty complex sets and unsoldering and soldering , testing of and value idenentification of components is required , so if you cannot perform these then you could be putting alot of money into it and never finding the problem.
if you would like any more info , I'll bee glad to assist you
Hello, I posted this earlier but it applies in this case so here goes,
The chirping sound is either a shorted Horizontal Output Transistor (HOT) /
Power FET (whichever one is used in this case) or the IHVT (Flyback
Transformer) has developed a short in its windings. In ether case both
components will have to be replaced. I would suggest you have a
qualified TV technician come over and troubleshoot the problem and give
you an estimate on the repair. However, if you are doing this repair yourself take into mind that the HOT and the IHVT (flyback) are in a series circuit configuration and if the Flyback is bad I would change out the HOT also, and vice verse.
He replaced the Integrated High Voltage Transformer (IHVT) (I so hate the term flyback even though it is descriptive of the function of the component). However he may have only solved part of the problem. My next question is did he perform a diagnostic on the CRT (picture tube)? It may well be the CRT, but I would first suggest that you have the repairman check the voltage and signal levels in the horizontal section of the TV and check the video signal and voltage levels at the output of the Video processor to the CRT socket board. Then after these are tested and proven to be within specifications, then run a diagnostic on the CRT using a CRT test set. This way he'll know for sure if the problem is in the circuitry or the CRT.
I am suspecting that the first trouble you experienced was the set was completely out? If so that is why he may have replaced the IHVT. He should have also replaced the Horizontal Output Transistor because it is in series with the IHVT and would have taken some of the damage that the IHVT would have sustained. So having him check that too would not be out of sorts.
Base on the service manual information, yes IC561 could be defective.
You did not get the +15 volts because the TV failed to power up and the majority of voltages are coming from the flyback transformer.
Ok first of all the only way the trippler could have caused this was if it shorted, and you would have known if that happened, because of the fire that would have occurred. So let's go back to square one. did you check the primary power supply in the back of the chassis? check it first for a blown fuse. I you can not find that then disconnect the power connection to the high voltage board and secondary power supply (switching power supply) and see if you can get the supply rail to the secondary board up (you will need a schematic to see the voltage values that should be there. Now if that fails to produce results you will have to assume that the secondary power supply is the culprit (it usually is). The funny part about this is the one component no one ever tells you to test is the one you should test all of the time and that is the IHVT (Integrated High Voltage Transformer) some folks refer to it as the "flyback" transformer. Now one of the biggest problems happens at this point there are three tests that you have to run the equipment needed is a s follows:
1) an oscilloscope
2) Universal Signal Analyzer/Generator with Ring Test ports
3) A capacitance meter or a LCR 103 (I prefer the LCR103)
4) an ohmmeter
Now here is what you need to do to test the IHVT
1) Remove the IHVT from the circuit board (desolder it)
2) Remove the HV cable clamp (holding the HV cable to the base of the IHVT)
3) (Test 1) Perform a resistance test between the posts of the IHVT looking at the schematic to see which posts are wired to each other. (now this test is only good for pointing out open coil windings not shorted coil windings) if this test passes (no opens) go to test 2
4) (Test 2) perform a ring test of the IHVT. Now this is why you need the Signal Generator with ring test ports. Connect the cable from the ring test ports to the primary side of the transformer, see the schematic to determine the primary os the transformer (the side connected to (actually between) the Horizontal Output transistor and the power supply. turn the ring test actuator fully counterclockwise, turn the test selector to ring test and slowly turn the ring test actuator clockwise until the screen reads greater then 10 rings, if ten rings can not be achieved then the IHVT has a short in it and should be considered as bad and in need of replacement. if this test passes go to test 3
5) (Test 3) The last test is the capacitance test. This test is a test of the internal capacitance of the IHVT. This is measured from the HV anode of the transformer to the ground post of the transformer. connect the negative end of the capacitance meter to the ground post of the transformer and the connect the positive end of the capacitance meter to the anode of the IHVT (this is the end that the cable was removed from, You will have to use a probe with a wire attachment to it to make contact with the anode connection in the IHVT. Once that is done the capacitance meter should read around 2.7nf or above. A reading of .3nf means the capacitor is open. Note: However certain flybacks may have the value of 4.5nf, 6nf and 7.2nf and sometimes the internal capacitor pin is connected to circuits (feedback) instead of ground, so be aware of this when testing. If this test passes then the problem is not the IHVT.
However if any of these test fail then the IHVT is to be considered as bad.
Now if the IHVT is good, then you will have to test the following components and their respective circuits:
The Horizontal Output Transistor, The Switching power supply MOSFET, The switching power supply transformer (perform ring test just like the IHVT), and pay special attention to the capacitor on the 6 volt rail (This capacitor is known to go bad often) as seen on the circuit board, The schematic will have all of the part location numbers as seen on the board.
This is a logical start as opposed to the shotgun approach a lot of forums seem to lead to. Let me know if this helps you.
i need m# if you don,t have eny power noled in front of tv a green lite ck out fuse if that good. ck hozoutput it by the flyback most of time if the hozout is bad you should replace flyback the part#
is on the side a tag.the hozoutput the # you can se it. if you have a onm metter you can ck the hozoutput in dioe mod.
i till you this you can call me if yon need to 518-798-7560 ask for robert i see what i can help you?
Verify service number from back of set................. Probable bad IHVT ( aka flyback transformer) and possible shorted horizontal output transistor........T.
Please let me know if # is F36650 YX01.............
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