My 12 years old TV set is a PHILIPS 42PFL7404, the PS is a DELTA DPS-298, and the LG panel is LC420WUF. Three weeks ago the screen starts blinking slightly and a minute later went black, but with audio. I desconected from the power line, power on again and in a few minutes the same problem. I removed the back cover and all the PS components look good. Power up again and the problem disappears, go into the service mode and find (Error code:17) and 11000 display hours. Put the cover again and the screen goes black in 2 minutes. Then check all capacitors, diodes and Mosfets, resoulder the main connections, update the firmware and close the back cover. Two minutes after power on, the same problem. Remove again the cover and using a heather fan at 100ºC I found a sensitive zone that generates the same problem in a few seconds. But the back side smd componentes involved are from the feedback (zener and opto) and supervision of the main switching PS secondary and not from the inverter circuits. I suspect the CCFL tubes but I have doubts with the PS...
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Re: PHILIPS 42PFL7404
If you warm up the opto and zener and the fault returns quickly then you cool the opto and zener, does the fault go away just as quickly. If so I would consider replacing those components first.
What zener and opto? On the power supply or mainboard?Last edited by dick_barton; 09-16-2021, 07:07 AM.Willing to help but I'm no expert. -
Re: PHILIPS 42PFL7404
These componentes are in the PS: IC953(TL431) and the opto PC901(NEC2561), but some other componentes round.
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This is an LG edge LED lit LCD Display. The LEDs are on the bottom edge of the display. There are 2 bars (left and right) Each bar has many LEDs and a 6 pin connector. Each pin drive several LEDs thus is the highest current flow / heat junction. The weak lead free solder gradually fails with thermal expansion/contraction cycling and increases resistance. PSU will compensate up to a point, then when the current is too high, PSU just shut down the backlight causing a dark display. I have even seen one which the connector just fell off as solder points became completely detached.... -
Hello,
I bought a SH Philips 55OLED804/12 TV with known defect in an attempt to repair it for personal use.
The symptoms when bought: Philips logo appears then tv turns off
Things tried so far:
1. Powering it on: Philips logo shows on the screen, sometimes with some minor artefacts then shuts down. Red status led flickers rapidly into two batches then repeats
2. Put it in recovery mode by pressing joystick down then plugging it to mains: The tv shows the logo then shows the android animation along with some minor artefacts on the screen... -
Hello, guys!
The same 32" Philips TV I was having video issues, but now I don't have standby led at all. Someone here shared with me the schematic of the power supply, and checking the voltages, I see right after the resistor R604 I'm getting 1.6 v which is too low for enabling the Gate of the Q601 mosfet (the diagram says 4.2). On the R614 resistor I'm getting 181 V in and 117 V out, then through R603 I'm getting the same 117 V in and 59.9 V out, finally getting the latter voltage in the R604 BUT getting just 1.6 V out, which is the voltage that goes on to the Gate of the Q601... -
Philips 8200 series 65PUS8204/12 stuck at Philips Logo, it does not reboot it just stays on the logo.
It does power up when pressing the power button.
I already try the power button while plugin the plug with no result.
Also put the latest firmware autorun-TPM191E_R.001.004.100.000.upg on a MBR/FAT32 USB stick at USB port2 with no result either.
Could this be an PSU or eMMC issue ? -
I have a problem with the back-light on a 12-years-old PHILIPS 42PFL7404 TV with DELTA DPS-298 power supply. Screen time is 11000h. A month ago the image started to flicker slightly and after a minute it turned off, but keeping the audio. It was necessary to disconnect from the line to turn it on again, with the same symptoms (Error code:17). The PSU seems to have all the components and welds fine. For a while I ran it without the back cover and it held up well without shutting down. With a heat fan I looked for the susceptible area and found it in the return circuit and supervision of the power...
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