Question about Philips Magnavox 27MS343S 27" TV

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Philips 21" L01.2A Chassis HV Shutdown

TV set shutdown after few seconds of coming on. Set will stay on longer if you continuously change channel.Problem was intermittent before but goes hard now. I have done some resoldering thinking that is just some cold solder issue. Screen flickers with green, and sometimes red color before shutdown. I have checked the power supply section, voltages seems to be ok. The main supply output of SMPS(B+) bothers me because per schem. diagram it should be 130Vdc for the 21" set and I'm reading 139dc volts. What could be causing this "abnormal" voltage output of SMPS? I have replaced the swithcing regulator IC and some electrolytic caps in the horizontal driver ckt. I have read that most of the Philips product having this chassis no. encounter the same problem but no one seems to solve the problem. Glad if anyone from the masters can help. Thanks in advance. God bless. Thanks.

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  • bashlort Oct 07, 2007

    This set is just a year and a half and out of warranty. Hoping that this is just an easy fix since I understand electronics but have not repaired TV a long time ago.

  • bashlort Oct 26, 2007

    Hi Shuttle83,

    I managed to check the output of the video processor and seems to be fine. I was able to put the set in service default mode and its blink corresponds to error 11 & 2. both high beam current problem. I tried to adjust the screen voltage but still no joy. I am only equipped with DMM in troubleshooting my TV set. Will a defective yoke will cause this problem? I have found some abnormal (black like burnt) colors in the yoke. Thanks for advise.


  • sekou02 Jan 14, 2008

    just moved into a new apartment, TV was working fine here for 2 weeks then just started acting crazy. Turn on and it will automatically turn off and on then going off with the green light still on. I had issues with this tv 2x before, 1st within a week of getting it, was doing this was but was under warranty... then it started up again a few months ago... Took it to the shop got it fixed and I thought all was well, but I can not afford to keep putting this in the shop... Is there anything that I can do...

    Thanks in Advance...

  • jcarloss Mar 04, 2008

    hola amigos espero me puedan ayudar estoy tratando de reparar un tv philips 21" modelo 21pt5026/71 chasis L01.2A el cual vino con problema que no prendia (esta falla debido segun cliente a que estuvieron presionando el power del control remoto y del tv varias veces ) solo encontre el transistor horizontal BUT11APX lo remplace por el BUT11A, lo demas parecia estar bien asi que encendi el tv y lo que pasa es que a los 2 segundos se apaga , cuando enciende se ve la imagen y audio normal todo solo que al comienzo sin antena se veia la trama azulada . y cuando se conecto antena la imagen parpadeaba y se tornaba de los tres colores uno tras otro ..y se apagaba . cambie el regulador , descarte la memoria , cambien el I.C: vertical, transistores driver horizontal y nada no se donde pueda estar la falla cualquier ayuda bienvenida y estare agradecido .



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I have the same problem on this chassis L01.2A.Still no solution.

Posted on Jan 11, 2008

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Hello bashlort, The increase in voltage may be to some circuit loading being removed this is a sign that something may have increased in resistance or something may have opened in the attached circuit. Have you taken any voltage measurements in the video section of the set, if not check the voltages on the pins of the video processor IC and follow the connections up to the CRT socket, be sure to pay special attention to the focus and screen grid voltages. If those are ok check the voltages in the horizontal section including oscilloscope measurements for drive signals. Please inform me of your findings. Thank you, Shuttle83

Posted on Oct 07, 2007


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This is the Famous 3 strikes and out for RCA's--it tries to come on 3 times and if fails shutdown occurs.

The high pitched sound may be a short or could be something arcing--if the sound comes from near the very front of set--could be the HV splitter this set has arcing.

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Re:"shutdown after video comes up the green power light stays on but the set will not shut down while changing channels."


I do not think this has anything to do with logic circuits and video processing. When you stay on one channel the horizontal and vertical alignment circuit works more than if you change channels all the time.
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On the DPTV chassis that should shutdown the vertical deflection which would leave audio working worse case scenario would also be the HV generator and Horizontal output.

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