samsung LN-S4051D diagnal lines

[nomoresonys]

Re: samsung LN-S4051D diagnal lines

I think I messed something up earlier, I was trying to test voltages on that mosfet with tv on, had a probe on neg. of bridge rec. and when I touched drain or source it was one of them, then the backlights went out, now they won't come back on even after heating that small section like before, but the damn thing did quit clicking every 5 seconds.

[nomoresonys]

Re: samsung LN-S4051D diagnal lines

ok, shorted all 3 legs, it's 197 ohms drain to source.

[lotas]

Re: samsung LN-S4051D diagnal lines

think i found a bad mosfet, QI802, read funny, took it out, getting 192 ohms from drain to source, isn't that way too low?

Discharge its mosfet (short all three legs with a metal object) and check again with a multimeter.

[nomoresonys]

Re: samsung LN-S4051D diagnal lines

think i found a bad mosfet, QI802, read funny, took it out, getting 192 ohms from drain to source, isn't that way too low?

[nomoresonys]

Re: samsung LN-S4051D diagnal lines

Thanks Lotas.

[lotas]

Re: samsung LN-S4051D diagnal lines

PFC (Power Factor Correction) does not work.

[nomoresonys]

Re: samsung LN-S4051D diagnal lines

seem to have a strange reading on bridge rectifier, when tv backlight is on the dc voltage on the outer 2 pins are 106 volts, where I think it should be around 160, all diodes of bridge rec. read correct and inner 2 legs are 120 ac as expected, any thoughts on why the voltage is low?

[nomoresonys]

Re: samsung LN-S4051D diagnal lines

well this one crapped out again, getting the clicking of the relay every 5 seconds, fixed it once with electro caps replacement and reflow of solder joints, lasted a few months now its back same thing, clicks every 5 seconds. When powerboard is unhooked from mainboard clicking stops but backlights don't come on, when heating area of ics801 for a minute or two tv comes on for 15 minutes or so no clicking, replaced or checked all caps and resistors in that area, anyone know if heating ics801 is making it work for that 15 minutes or should heating it have no effect on the ic as in letting the tv work for that 15 minutes??: sj pic of powerboard: https://www.shopjimmy.com/samsung-bn...ight-inverter/

[nomoresonys]

Re: samsung LN-S4051D diagnal lines

been checking these ics, the readings seem funny, ic101 from top=1.79v left=2.8mv right=3.34v. ic102 top=2.7mv left=13.3v right=7.9v. ic1702 top=starts at 22 mv keeps going up, left=3.7mv right=5.09v, middle=2.5v, which I thought the middle should equal the top, seems like one or all of these are messed up, thinking this might be causing my snowy picture, any ideas?, thanks.

[nomoresonys]

Re: samsung LN-S4051D diagnal lines

from reading, I think a snowy picture is caused by a bad IC or eeprom?

[nomoresonys]

Re: samsung LN-S4051D diagnal lines

the panel # is LTA400WT-L01, sticker on mainboard # BN94-01091B, wondered if anyone has had success using a mainboard with a different number, BN94-01091A or BN94-00864A, for example, Thanks.

some places say it will, some say it won't, dunno?

[nomoresonys]

Re: samsung LN-S4051D diagnal lines

the panel # is LTA400WT-L01, sticker on mainboard # BN94-01091B, wondered if anyone has had success using a mainboard with a different number, BN94-01091A or BN94-00864A, for example, Thanks.

they look identical?

[nomoresonys]

Re: samsung LN-S4051D diagnal lines

the panel # is LTA400WT-L01, sticker on mainboard # BN94-01091B, wondered if anyone has had success using a mainboard with a different number, BN94-01091A or BN94-00864A, for example, Thanks.

[nomoresonys]

Re: samsung LN-S4051D diagnal lines

cooked it again, no difference, read about somehow shorting the eeprom, then resetting in menu but cant get a menu up, because pic. is too snowy.

[nomoresonys]

Re: samsung LN-S4051D diagnal lines

putting this one on the back burner, out of ideas.

[nomoresonys]

Re: samsung LN-S4051D diagnal lines

http://assets.shopjimmy.com/media/ca...01370d-top.jpg, anyone know where the test points are on these, thanks.

[nomoresonys]

Re: samsung LN-S4051D diagnal lines

cooked it at 400 for about 15 minutes no dififference.

[nomoresonys]

Re: samsung LN-S4051D diagnal lines

yeah, I guess the only thing left to do is cook it, was hoping it would be an easy component to switch out, thanks.

[freakaftr8]

Re: samsung LN-S4051D diagnal lines

its most likely a bad connection under one of the main IC's on your mainboard. BGA style which means ball grid array. Try meeting of the Board like I have done in an oven at 385 degrees for 10 minutes but suspect buying a new mainboard. are you confident you getting proper output voltages from power supply?

[nomoresonys]

Re: samsung LN-S4051D diagnal lines

wish I could find a service manual for this, electrotanya's training manual is pretty useless.