Philips PTV916 shutdown problem
 

I'm working on a Philips 60P8342 (P916 chassis) that shuts down about
3 to 5 seconds after turn on. I have the electronic version of the
service manual and so far everything I've checked looks good. The low
voltage power supply is regulating correctly and it has horizontal and
vertical deflection. I tried pulling the convergence plugs in case a
convergence IC was shorted. I also pulled the CRT sockets in case one
of the CRTs was shorted. It has high voltage until shutdown.

The manual I have isn't very helpful in determining the cause of
shutdown. Does anyone with experience on this chassis have any
suggestions? At this point I would be happy to take the risk of
disabling the shutdown circuit to see what happens. If it can't be
repaired inexpensively and quickly it will be scrapped anyway.
Andy Cuffe

On 11 Nov 2004 23:08:34 GMT, Ol' Duffer wrote:

In article ,
says...
I'm working on a Philips 60P8342 (P916 chassis) that shuts down about
3 to 5 seconds after turn on.

Do you get a blinking power LED?
If so, it will blink the error code.

Most common I have seen is error 2, which is
supposed to be vertical sweep failure, but usually
the problem is not in the vertical sweep, but in
the circuits that detect the presence of sweep.

If I am thinking of the right chassis, I have only
seen one with an actual large signal failure, and
the rest have all been flaky SSB boards. This is
the little board in the SIMM socket near the right
side of the set. In the case of the alleged error 2,
it has been a shorted input pin on the microprocessor,
the pin that receives the vertical pulse. These
little boards, which are the brains of the set, seem
to be chronic failure items. Of course there are
some SMD resistors, capacitors, and a transistor
that "condition" the signal before feeding it to
the SSB, but the signal path seems to always be okay.
And of course, the SSB is hard to get at and diagnose.

IIRC, there is a PC software and interface package
available to diagnose these new chassis. Like anyone
can afford such a thing in this day of disposable
TV's. Maybe the factory has one. Good luck!

That sounds like the chassis I'm working on. I will check on the
error code next time I work on it. Thanks for the tip.
Andy Cuffe

On 11 Nov 2004 23:08:34 GMT, Ol' Duffer wrote:

If I am thinking of the right chassis, I have only
seen one with an actual large signal failure, and
the rest have all been flaky SSB boards. This is
the little board in the SIMM socket near the right
side of the set. In the case of the alleged error 2,
it has been a shorted input pin on the microprocessor,
the pin that receives the vertical pulse. These
little boards, which are the brains of the set, seem
to be chronic failure items. Of course there are
some SMD resistors, capacitors, and a transistor
that "condition" the signal before feeding it to
the SSB, but the signal path seems to always be okay.
And of course, the SSB is hard to get at and diagnose.


You were right. A new SSB board fixed the problem.

Andy Cuffe