Weird Panasonic TV behavior - troubleshooting suggestions?

[John Hudak]

Hi:
I have a Panasonic CT-27D10B 27" tv that exhibits the following:

1) set is operating normally, then, instantaneously it shuts off (as if
someone used the on/off switch to turn it off). It will come back on
anywhere from 10 seconds to maybe 5 mins. Sometimes it will display the
setup screen, sometimes not.

Any ideas what may be causing this?

Thanks
John

 

[Meat Plow]

Hi:
I have a Panasonic CT-27D10B 27" tv that exhibits the following:

1) set is operating normally, then, instantaneously it shuts off (as if
someone used the on/off switch to turn it off). It will come back on
anywhere from 10 seconds to maybe 5 mins. Sometimes it will display the
setup screen, sometimes not.

Any ideas what may be causing this?

Start with the mains as the their removal for whatever
reason/problem usually results in many sets going into the setup mode upon
restoration of the mains.

 

[John Hudak]

Start with the mains as the their removal for whatever
reason/problem usually results in many sets going into the setup mode upon
restoration of the mains.

That would be my inclination as well...however, given the behavior of
this beast, what do you think would be the cause? board trace? solder
joint? or a component?
I can't even guess what would be causing the problem - it does not seem
to be temperature related. Pressing on the board when it dies does not
seem to bring it back. There is a thermistor right after the PS
section. I haven't figured out what it does - suggestions?
Thanks
John

 

[Meat Plow]

That would be my inclination as well...however, given the behavior of
this beast, what do you think would be the cause? board trace? solder
joint? or a component?

Hard to say as it could be any of the aforementioned. I would rule out a
physical problem first. Get the set in a place where you have lots of
light, a bright portable light, can easily see both the top and bottom of
the board and where you are comfortable and give it a good visual. Have a
magnifying glass handy too. I have one of those stereo magnifying visors
and frequently use it to inspect solder joints.

I can't even guess what would be causing the problem - it does not seem
to be temperature related. Pressing on the board when it dies does not
seem to bring it back. There is a thermistor right after the PS
section. I haven't figured out what it does - suggestions? Thanks John

The thermistor might be used in the degaussing circuit or as a current
inrush limiter. Barring failure on your part to find a physical defect you
might want to get a schematic that has some voltage and scope test points.
I've run into situations where poor solder joints or PC board pass thru
connections were not discernible even under magnification (not saying this
is your problem.)

 

[nipperchipper]

connections on the relay and on the thermistor were common problems also
resolder the vert o/p ic as their connections will break as well