Hi all,

I am hoping someone here may be able to help me with solving an intermittent
fault with our family TV....... PLEASE ?.
It is a Phillips 21PT2012 / 79R and has what I think is the serial number
of BZ000231 723707 on the back cover.
The fault manifests itself as sudden loss of all picture, and light from the
screen and loss of sound at the same time, anywhere from 5 seconds to a few
minutes from switch on.
This started a week or so ago, and a turn off seemed to fix it, and now it
will not run longer than a minute or so without dying. It seems like the HT
supply drops out suddenly,
but as I understand it the power supply rails for all the circuitry on this
type of appliance may very well all come from one switching supply, and a
fault there could wipe out everything?
I have a reasonable understanding of electronics, and a good Fluke
multimeter, but no cct. diagram, and no experience with TVs. Any
suggestions? I think that the set is about 4 years old, and I guess it must
be some component that is built to a commercial standard starting to break
down, but I was hoping that there may be hope rather than junking it?
Thanks for any assistance.

Tim

Sometime heat generating components can get flaky because of an accumulation
of dust causes them to overheat.
You might try opening the case and give it a good vacuuming. Of course the
unit should be unplugged for an hour or so before you open it up. Also look
for signs of overheating on any of the components such as discoloration or
charring. The most common problem on power supplies is capacitors that get
leaky which causes them to overload the resistors feeding them generating a
lot of extra heat so if you find a charred resistor it is probably not the
root cause of the problem.


"Tim" wrote in message
...
Hi all,

I am hoping someone here may be able to help me with solving an
intermittent fault with our family TV....... PLEASE ?.
It is a Phillips 21PT2012 / 79R and has what I think is the serial number
of BZ000231 723707 on the back cover.
The fault manifests itself as sudden loss of all picture, and light from
the screen and loss of sound at the same time, anywhere from 5 seconds to
a few minutes from switch on.
This started a week or so ago, and a turn off seemed to fix it, and now it
will not run longer than a minute or so without dying. It seems like the
HT supply drops out suddenly,
but as I understand it the power supply rails for all the circuitry on
this type of appliance may very well all come from one switching supply,
and a fault there could wipe out everything?
I have a reasonable understanding of electronics, and a good Fluke
multimeter, but no cct. diagram, and no experience with TVs. Any
suggestions? I think that the set is about 4 years old, and I guess it
must be some component that is built to a commercial standard starting to
break down, but I was hoping that there may be hope rather than junking
it?
Thanks for any assistance.

Tim

Tim wrote:
Hi all,

I am hoping someone here may be able to help me with solving an intermittent
fault with our family TV....... PLEASE ?.
It is a Phillips 21PT2012 / 79R and has what I think is the serial number
of BZ000231 723707 on the back cover.
The fault manifests itself as sudden loss of all picture, and light from the
screen and loss of sound at the same time, anywhere from 5 seconds to a few
minutes from switch on.
This started a week or so ago, and a turn off seemed to fix it, and now it
will not run longer than a minute or so without dying. It seems like the HT
supply drops out suddenly,
but as I understand it the power supply rails for all the circuitry on this
type of appliance may very well all come from one switching supply, and a
fault there could wipe out everything?
I have a reasonable understanding of electronics, and a good Fluke
multimeter, but no cct. diagram, and no experience with TVs. Any
suggestions? I think that the set is about 4 years old, and I guess it must
be some component that is built to a commercial standard starting to break
down, but I was hoping that there may be hope rather than junking it?
Thanks for any assistance.

Tim




ANd don't forget there is big, damm big, voltage in there that can kill you!