[TV] Re: Zenith PVR5263RK - Need service manul and/or advice
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[TV] Re: Zenith PVR5263RK - Need service manul and/or advice
I have just uploaded the schematic to my site if you need it.
http://schematics.myvnc.com/
Harry Fogarty
Harry`s Electronics
#4- 1144 MacKenzie Rd. North
Williams Lake
British Columbia
Canada
Tel: (250)-
Fax: (250)-
From: rick@xxxxxxxxxxxxxxxxxx
Reply-To: tv@xxxxxxxxxxxxxxx
To: tv@xxxxxxxxxxxxxxx
Subject: [TV] Re: Zenith PVR5263RK - Need service manul and/or advice
Date: Tue, 5 Apr 2005 10:55:17 -0700 (PDT)
Thanks John,
-26v is the line that pulsates. I looked at it on the scope last night
and it looks like it drops to ground potential for a split second, then
quickly rises back up and repeats.
I will check the diode and perhaps filter cap esr and post results.
Thanks,
Rick
> Rick, I'm sending this message again because I don't think it went
> through.
> But all I have left on this one is to check cr3419 and cr3420 and make
> sure
> you have a clean waveform. This is you + & -
> 26volts for convergence. somtimes these diodes break down under a load or
> the filters get dry and do not filter right and there is ripple.
> good luck on this one
> john
>
>>From: Rick <rick@xxxxxxxxxxxxxxxxxx>
>>Reply-To: tv@xxxxxxxxxxxxxxx
>>To: tv@xxxxxxxxxxxxxxx
>>Subject: [TV] Re: Zenith PVR5263RK - Need service manul and/or advice
>>Date: Mon, 04 Apr 2005 19:07:32 -0700
>>
>>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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