I just replaced the FLYBACK transformer on my 56' RCA rear projection TV model P52921 (Flyback part # 239111, 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!
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maybye you did not get the high voltage wires back into flyback good enough. or it could be the high voltage splitter. did you use the correct HOT? and please describe the sound, was it a hissing sound like high voltage?, a snapping or arcing sound?
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well a hissing sound is definitly a high voltage leak. replace the hot with correct one, and see if tv will fire back up. if it does look at the high tension wires, and crt's, in a dark room to see if you can see the voltage leaking. i doubt that it would be a bad solder connection. good luck
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I have a strong feeling you are right. I did check the soldering behind the FLYBACK and it was fine. I will replace the HOT in the next few days and update you on my findings. Thank you very much for your help!!!
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no, the HOT will not cause hissing sound. the HOT must work in order to get the tv fired up again. the HOT causes high voltage to be turned on. i am saying replace the HOT, because the tv is dead right now, right? you have to get tv running before we can locate the hissing sound, which is by all means a high voltage leak, and could destroy the tv if not found quickly. keep me posted.
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Ok maybe i should have explained the original problem instead of giving later events. Well intially the TV did not power up so I made a visual inspection of the mainboard where the FLYBACK is located and found that the FLYBACK has burnt circular marks on top. I decided that it was the failing part after a tech came look at it and got the TV back powering and working by what he claims "Soldering the back of the Horizontal output Driver" which I assume that it is another terminology for the FLYBACK (Please correct me if I am wrong). I decided to replace the FLYBACK and that is when I was able to get the TV back up and working for about a week with the exception of a slight blurr (lack of focus type of effect) vertically sweeping out the very right corner with a vertical green light at the very most right edge of the screen and ofcourse our old friend the "hissing noise" I described to you earlier. Let me know if that gives you more clues, thank you very much!
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the horizontal driver is not the flyback. it just drives the HOT. the HOT makes flyback develop high voltage. so it sounds like maybye you did not have to replace the flyback. anyway is the tv actually dead? i need a definite (yes )or (no) answer to that question before i can help you. that way i will know what to tell you to do next.
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Initially it was dead then the tech soldered the Horizontal output drive then it worked then it went dead again after 5 days. I thought the horizontal output drive is refering to the FLYBACK so I went ahead and changed it then the TV worked back again for another 7 days (with blurr and hissing noise) and now it is back dead again.
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Check the H.drive Q14302/301,T14301.Q14401,Check volts at C14208 should be 150-155v range,same volts at the DRAIN of the MOSFET,also check R14104,C14127,check B+ line from pin 8 of T14101,to pin 6 of the regulator U14601,also check CR14111,R14135,
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check the fuses, and confirm that you do have current to tv first, then do you have any test equipment? and i need to know your skill level. you need at least (D.V.O.M.) digital-volt-ohm-meter
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I am trying to locate these numbers in the back and really having a hard time. I can see 3-5 letters and numbers but not as many as you indicated. Are we talking about the right chassis? I noticed that the outside cover says PTK195MB while the board itself has a metal mount that says CTC195M?
I do have a multimeter and good skill level but need some guidance to get this accomplished...thanks alot!!
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So if you want me to try to help you I will, but I prefer to do it my own way and check things as I say to instead of jumping ahead with hit or miss techinques like what Frank is telling you to check. I do have the correct print on your set, and several years of RCA experence. Sincerly, Jimmy Neutron
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Excellent Jimmy and thank you for all the help so far!
I will be more than happy to do it in that order. Just one request, whenever you ask that a part to be replaced I will need the part number so I can purchase it (very important). I am ready when you are.
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Tested T14101 for potential VDC across pin 3 and 4. I got no reading on the digital meter. The meter was oscillating back and forth with no reading registering.
Please note that T14101 on my board is located around W14 not A20. My chassis # is CTC195M
T14101 is a large coil. I loacted the number 1 on the board next to T14101 and counted from that location to identify pin 3 and 4.
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ok, i located another print, and the locations are like yours. is your meter set on DC volts? make sure your meter is set on proper voltage scale, make sure you have a good ground for the black lead of meter, test your meter on some batteries to confirm that the meter is working properly on DC scale, and check again, to confirm your first readings. the T14101 is a switch mode transformer, and we need approx. 145-156 volts DC on pins #3 to GRD, and pin #4 to GRD. you can get a good GRD from CR14210 (bridge rectifier), located real close to 5 amp line fuse, so double check and let me know. also if you want to give me your e-mail address we can do it quicker. J.N.
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OK test results are pin 3 is showing 159.3 VDC and pin 4 is showing 159.5 VDC.
Prior to the measurment checked meter reading on a 1.5 volt battery and then located the bridge rectifier CR14102 and used the (-) lead as ground. Let me know if these results are satisfactory, my email is: [email protected]
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OK, READINGS ARE GOOD. I SENT YOU SOME E-MAIL TODAY WITH MORE TESTING DID YOU GET IT? OUR E-MAIL SHOULD SHOW UP WHEN YOU GET THE MESSAGE, AND THEN WE WILL WORK FROM THAT. JIMMY
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Hi JIMMY NEUTRON ..I need your support with this chassis ..I have a similar issue ..but i cant follow up your instructions because you did not post here you sent email to Haitham..The chassis have 156 VDC on pin 3 of T14101 , & PIN 4 OF T14101 but not in 8,i verify everything around the IC U14101 but are ok..the voltage on pin 6 si oscillating between 8-11 volt..Thanks in advance
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