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 > > ------------------------------------------ > Submit A Repair Tip For Everyone Here: > http://www.tech-assist.org/secure/tip/main.html > ------------------------------------------ > To REMOVE your email address, click here: > http://www.tech-assist.org/unsubb.html > To CHANGE your email address, click here: > http://www.techassist.net/forms/change.html > > ------------------------------------------ Submit A Repair Tip For Everyone Here: http://www.tech-assist.org/secure/tip/main.html ------------------------------------------ To REMOVE your email address, click here: http://www.tech-assist.org/unsubb.html To CHANGE your email address, click here: http://www.techassist.net/forms/change.html