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

["al m" <ampm@xxxxxxx>]

Change the resistor on the blue CRT board. 120K I think.
Al Marquardt
ampm@xxxxxxx
Al Marquardt Electronic Repair
206 W Main
Girardville Pa. 17935
----- Original Message ----- 
From: "Rick" <rick@xxxxxxxxxxxxxxxxxx>
To: <tv@xxxxxxxxxxxxxxx>
Sent: Wednesday, April 06, 2005 6:01 AM
Subject: [TV] Re: Zenith PVR5263RK - Need service manul and/or advice


> OK everyone, here is an update: Some things fixed, some things possibly
> not right...
>
> I took John's advice (below) and checked the voltage at the diodes. The
> mess was still there
> on the -26v diode so I replaced the diode and filter cap. The set was
> stable for a long time. I thought
> the problem was solved but eventually the "bounce" came back.
>
> I decided to check the +26v side and noticed that the convergence board
> was not getting +26v, but it was
> there at the diode. Blown fuse on the +26v supply. I hadn't noticed it
> before because the glass window was
> covered with a blob of adhesive. I determined that dead side of the fuse
> wasn't grounded out and jumped it with
> a fused ammeter to see what would happen. Current through the meter was
> not high so I jumped the blown fuse with
> a wire. Of course now the convergence POTs have significant affect on
> the TV compared with before. Also,
> the odd pulsating has not returned on the -26v supply. I let the TV warm
> up for quite some time and all seems well.
> There does seem to be some noise on the +26v supply, however, so I will
> replace it's filter cap.
>
> There's something up with BLUE, maybe someone has seen this before.
> When I pull up a PIP box or the menu, blue is missing from the vertical
> lines of any borders/boxes.
> If I go to the convergence adjustment setting in the menu, the two
> vertical lines are not white because there is very
> little blue in them. If I then turn off the red and green CRTs the
> vertical lines for blue are tiny slivers compared to the
> thick lines of R and G. Also on this menu all the text at the top
> ("Press FREEZE to select the color...") is in blue only and
> is virtually unreadable because of the lack of vertical blue lines.
>
> Thanks everyone, I'll keep you posted...
>
> -Rick
>
> rick@xxxxxxxxxxxxxxxxxx wrote:
>
>>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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