Philips 42PF9831D/10 Problem

[juni0r123]

Hi everyone,
I have an annoying problem with a philips 42PF9831D/10 which I just don't have enough knowledge to solve.

Some of the time the TV functions just fine.
But more & more often the TV switches off & goes into protection mode
The red led on the front shows one long flash & 4 short.

I know this is a problem with the SSB board as I have another set exactly the same.
I repaired the power supply on the other one & it's working just fine.
If I swap the SSB from the semi working one to the good one, I get exactly the same problem.

One thing I've noticed purely by chance is, if I leave the coax aerial out
then the TV seems to behave normally,
but if I plug the coax in whilst on, most times it trips straight away.
If the cable is already in, then it mostly trips just as the channel is about to appear, but not every time.

It's 100% not the cable as this works fine with other TV's.

I've tried to source another SSB for this tv but this is proving impossible as it's an old set & there don't seem to be many around.
Just my luck as I really like the 4 ambilight setup on these.

The SSB board is a bit more complex than the usual PSU repairs I've done.
so any advice would be greatly appreciated.

Thanks for taking the time to read this
John

[dick_barton]

Re: Philips 42PF9831D/10 Problem

One thing I've noticed purely by chance is, if I leave the coax aerial out
then the TV seems to behave normally,
but if I plug the coax in whilst on, most times it trips straight away.

Can you use your voltmeter and see if there's a voltage between the aerial coax and the tuner earth which may be causing the problem.

[tn245]

Re: Philips 42PF9831D/10 Problem

One long flash and four short according to the service manual = Audio error

Error 14 (Audio protection). The detection is done on the
audio board itself. Several items are monitored:
overvoltage, overcurrent, DC level on the speakers and the
audio supply voltages. If one of these items fails, the
audioprotection will switch off the main supply. All supplies
will drop, the standby processor “thinks” there is a mains
dip, and will reboot. At the beginning of the boot process,
the audio-protection line is monitored : if this line is “active”,
the set will go to protection and will blink error 14.

[budm]

Re: Philips 42PF9831D/10 Problem

Easy to check for DC on the speaker terminals since it is easy to get access to. I have SONY TV with the same audio protection scheme, it has failed Class D amp with DC showing on the speaker terminals.

[juni0r123]

Re: Philips 42PF9831D/10 Problem

Hi everyone,
Thanks for all the feedback & things to check, really appreciated.

Another quick question though,
How can I check the voltage at the speakers if the TV trips straight into protection mode?
The same applies to checking between the tuner earth & coax?

I didn't have a lot of time to check things to day, but I did try the following.
I turned the TV on with no aerial connected & again it turns on fine.
I then switched to HDMI & plugged the aerial in.
The TV continued working, but as soon as I switch it over to TV it fails.
I also tried setting the volume to 0 but in TV mode it still goes into protection.

Regards
John

[budm]

Re: Philips 42PF9831D/10 Problem

You hook up the meter probes (set meter to DCV) to the speakers terminals, then plug TV into the outlet and then turn on the TV while looking at the meter display.

[budm]

Re: Philips 42PF9831D/10 Problem

BTW, look at the model number label to see if your TV chassis is
FJ3.0ELA

[juni0r123]

Re: Philips 42PF9831D/10 Problem

You hook up the meter probes (set meter to DCV) to the speakers terminals, then plug TV into the outlet and then turn on the TV while looking at the meter display.

The way I worded that probably made me sound more of an idiot than I am.
It's not how to measure DCV it was if the set's not starting would it affect the reading.
but I guess I'll see a voltage spike as it trips.
If time permits, will try this tomorrow & report back

& yes the chassis is PJ3.0E LA

Regards
John

[budm]

Re: Philips 42PF9831D/10 Problem

The set power switch is activated, the circuit will start first and then if it detects the fault then it goes into shutdown, yes, it is going to happen fast and your meter may have fast response time to show the fault.
Otherwise you will have to dig deep and narrow down to which fault causes the shutdown.
Post #3:
Several items are monitored:
overvoltage, overcurrent, DC level on the speakers and the
audio supply voltages.