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

  • From: "al m" <ampm@xxxxxxx>
  • To: <techassist@xxxxxxxxxxxxx>
  • Date: Fri, 31 Jan 2003 08:24:26 -0500

Looks like your cathode voltage is too low too. Did you check your 200V
line.
al marquardt
ampm@xxxxxxx


----- Original Message -----
From: "Damon" <DAMON101@xxxxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Friday, January 31, 2003 7:36 AM
Subject: [TechAssist] Re: Samsung TV, model TXJ2554 chassis K51A -black
screen SAMS 4256


>
> I get a feeling ( 8-0).....that your screen control is messing with your
> cathode voltage. and this unit I believe has IK feedback.
> Yeah your screen voltage is too low, isn't there a boosted supply tied
into
> the screen control circuit on this? If so, check it. (You have schematics,
> right?) If not, then the IHVT will need replacement.
>
> Damon Brunger
> Telrad Electronic Services
> Ft Wayne, IN 46815
> ----- Original Message -----
> From: "Gary McCartney" <gary@xxxxxxxxxxx>
> To: <techassist@xxxxxxxxxxxxx>
> Sent: Thursday, January 30, 2003 2:32 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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