[TV] Re: Zenith PVR5263RK - Need service manul and/or advice

["RonnieTucker" <rtucker@xxxxxxxxxxxxxxx>]

Hi Rick
   What is the 9-number on the convergence board and the main power supply.
Ronnie
----- Original Message -----
From: "Rick" <rick@xxxxxxxxxxxxxxxxxx>
To: <TV@xxxxxxxxxxxxxxx>
Sent: Monday, April 04, 2005 4:14 PM
Subject: [TV] Zenith PVR5263RK - Need service manul and/or advice


> Hello, I have a Zenith 52" rear projection TV.
> Would somebody please help me obtain a service manual or schematics for
> this TV?
> I have tried from a couple of places but met dead ends.
>
> The problem I am having is hard to explain but I will do my best.
>
> What follows is a long account of everything I have observed and tried
> so far.
>
> First the convergence is way out of whack and although I get slight
movement
> when adjusting the POTs on the convergence board, it's nowhere near
> enough to
> bring it back into whack =)
>
> Second, after the TV warms up, the voltage supplied to the convergence
> board and convergence amplifier
> (same circuit) becomes "unstable."  On a scope the line representing
> this DC voltage will begin to bounce slowly
> at first, then more rapidly (up to 2 or 3 times per second) and the
> amplitude of this oscillation increases.
>
> Since this distortion is in the convergence circuit, it manifests as
> picture movement on the screen and affects all three
> CRTs.  As the TV warms up and the voltage begins to drift, the top of
> the screen will bow down then bounce in time
> with the fluctuating voltage.
>
> I visually inspected all components, especially resistors, and did not
> find any obviously burned or otherwise expired components.
> Next I took a can of air used it to cool parts in suspect places.  I
> found a couple transistors and a resistor, all near each other, that
> when cooled slowed or even stopped the strange voltage fluctuation.
> Next I replaced the parts thinking they may have tired out, but the
> problem persists.  Now I suspect too much current is going through that
> section of the circuit for whatever reason and blowing air over the PCB
> only cures the symptom, not the underlaying problem.
>
> The front convergence board with the POTs has a Disable jumper to
> disable the convergence correction.  Setting this jumper will
> immediately stop the voltage oscillation.  Upon re-enabling the jumper,
> the voltage will be stable for a few seconds and then ramp back up to
> full oscillation.
>
> Disconnecting just the BLUE input to the convergence amplifier will stop
> the bouncing and then the red and green convergence adjustments have
> much more effect on the picture than with the blue input connected.
>
> Disconnecting the output coils of any of the RGB amplifiers stops the
> bouncing but probably only because of reduced current draw through the
> whole system.
>
> I replaced the STKs which solved nothing, but neither did it break
anything.
>
> At this point I feel like I'm just shooting in the dark (and especially
> without a schematic).
> Somebody please help!
>
> -Rick
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