[TechAssist] Re: Samsung TV, model TXJ2554 chassis K51A -black screen SAMS 4256

  • From: <tvservice@xxxxxxxxxxxxx>
  • To: <techassist@xxxxxxxxxxxxx>
  • Date: Thu, 30 Jan 2003 14:33:40 -0600

your flyback is defective, we have replaced several inSamsung TV's for that
problem
Robert
tvservice@xxxxxxxxxxxxx
H & H Electronics Inc

----- Original Message -----
From: "Gary McCartney" <gary@xxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Thursday, January 30, 2003 1:32 PM
Subject: [TechAssist] Samsung TV, model TXJ2554 chassis K51A -black screen
SAMS 4256


>
> This is a Samsung TXJ2554 chassis K51A. (SAMS 4256)
> Turn set on, has sound but screen is black. Let it run and
> nothing changes usually, but one time the picture popped on normal all
> of a sudden. When turned on the next time, it had a black screen only
> again.
> I turned the screen control all the way up and the picture
> snapped in ok. Turned screen back down and the picture bloomed like
> crazy.
> It went really bright like it was saturated with too much contrast.
> Turned it back up to max. and picture was ok.
> Measured G2 on CRT board. Had an even voltage range but seems low- went
> from 76V low end to 276V high end. Disconnected CRT board and G2 voltage
> acted the same. Then I changed the G2 disc capacitor on the CRT board
> (.01uF 3kv). That didn't make any difference. I think flyback should put
> out around 500V on G2 at high
> end on most TVs, but it is only 276V. Is flyback defective?  Would The
> blooming be a sour tube? Why would it bloom  when I turn the screen
> down? Tapping on the tube neck doesn't make anything happen. R,G, B
> cathodes measure around 68Vdc with normal picture (seems low, ?). With
> blooming picture, I measure 33Vdc. With CRT socket removed, I read
> 191Vdc. The G1 pin measures approx. 0.4Vdc in any condition. So from
> these measurements it looks as if the CRT is drawing too much current.
>
>
> Do I have a bad flyback or CRT, or both?  Does anyone have a schematic
> with the dc voltages so I know if my readings are anywhere close to
> normal- which I don't believe they are?
> --
>
>
>
>
> Gary McCartney
>
> McCartney Electronics
> 7134 Fife Rd, RR 7
> Guelph Ontario Canada N1H 6J4
> Fax: (519)821-1530
> email: gary (at) number63.ca
>
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