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

[Rick <rick@xxxxxxxxxxxxxxxxxx>]

No dice...
I pulled the two resistors and checked them out-of-circuit. They were 
within tolernce and physically look as good as new.
Just to be sure, I measured resistance while accosting them with a heat 
gun (not a hair dryer, but a real heat gun).
They both held up remarkably well.

Thanks for the suggestion!

John Conti wrote:

>Rick, on the 9-1302 check two resistors, they are r3243 (110k 1/2 watt and 
>r3244 (82k 1/2 watt)
>they either change values or open up. They are located next to the upright 
>board that stands vertical. I think your having the same problem that I had 
>a few months ago and if so, drove me crazy before I located the problem. Let 
>me know how you came out on this, for if thats the problem it will sure save 
>others a lot of time.
>
>good luck
>john
>
>  
>
>>From: Rick <rick@xxxxxxxxxxxxxxxxxx>
>>Reply-To: tv@xxxxxxxxxxxxxxx
>>To: TV@xxxxxxxxxxxxxxx
>>Subject: [TV] Zenith PVR5263RK - Need service manul and/or advice
>>Date: Mon, 04 Apr 2005 15:14:05 -0700
>>
>>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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>>    
>>
>
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