Question about Philips 30PF9946 30 in. HD-Ready Plasma Television
I have a Philips flat screen, model number 30PF9946D/37. After being on for a few minutes the screen goes blank. I still have audio and the green light stays on. I've narrowed it down to two possible problems. It is either a bad temperature sensor (most likely), or it is the power supply causing it to short. I put the power supply board with all the heatsinks in the freezer over night and hooked it up today and it worked for a really long time. Then I turned it on after the screen inevitably went black and it lasted for a few seconds. This leads me to believe it is a bad temperature sensor, but I don't know where the temperature sensor is or where to get a new one. It also could be the power supply, as I have seen others with this issue. Any ideas? I see a lot of these questions on these boards with no answers, so I'm crossing my fingers. Also it is out of warranty and don't tell me, "Don't buy a Philips," or "Get a CRT." Thanks very much but this is what I bought and I would like it to work.
I have the same problem and was told by my local TV repair shop I needed a new LCD panel (at $2000!!!) which I don't believe for a moment since the panels themselves rarely fail. After digging around on the net, I came across a posting from "Arfa Daily" on the sci.tech-archive.com website which points to either the backlight inverter board or the power supply. So far, it is the only intelligent thing I've found that makes any sense. If anyone follows this up and sucessfuly repairs your set, please let me know! ....Acepayday
I will re-post his/her answer here but to read it yourself goto:
"Max" <[email protected]> wrote in message
[email protected] wrote:
Hello! I have a Philips 30PF9946D/37 30" LCD that no longer turns on.
Upon pressing the power button, the status LED goes from green to
amber then to red.
Is this a common problem with these?
Could be ps board.
It's a common problem with all LCD TV sets. First, try unplugging the
display panel's backlight inverter board. It is very common for these to
fail and cause the set to revert to standby. Otherwise, it's most likely
that the PSU itself is faulty - also very common.
Examine it *very* carefully for bulged electrolytics on the secondary side.
Note that these may be 'hiding' under bits of heatsink, so look carefully.
Also, check all large and heatsink-mounted devices, for bad (lead-free !!)
joints, which is another common cause of your described symptoms. Other than
this, you're a bit 'on your own' with LCD sets. There are other possible
causes, such as bad sound output chips, but if you really do have a power
supply problem that's not one of the things described, then you will
struggle to get to the bottom of it without schematics, and an intimate
knowledge of switchmode power supplies. These LCD ones are infested with
monitoring circuitry for output voltages and over-current conditions, and
they all work on the standby supply, so if *any* unexpected condition is
detected either at startup, or during use, the standby supply is momentarily
stopped, which causes the system control micro to reset back to its 'sleep'
condition, removing the 'power on' signal to the power supply. Depending on
the set, that may then be an end to it until you try to bring it out of
standby again, or it may just keep trying on its own, causing a flashing
If you can prove which board is causing the trouble, you might want to
consider just replacing that board. PSUs and inverters for many sets, can be
found astonishlingly cheap on the 'net and e-bay sometimes.
Posted on Nov 24, 2008
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