View Full Version : samsung lcd tv buzzing power supply/inverter


petehall347
01-01-2017, 05:58 PM
i have this samsung tv here with a buzzing BN44-00264A power / inverter board
it came to me dead . main fuse blown fs801s 6.3a
also a shorted fet qp801s qp802s ... not sure which was shorted but changed both anyway .
also changed up801s for good measure ..no other apparent faulty components in the area .
i haven't pulled any caps to test yet .i thought i would ask here first if anyone had any clues as to what is causing the buzzing .
noise seems to be coming from lp801s .
an important thing i have noticed when i plugged it into my mains power meter / conditioner i see it looking like the tv is pulling 3kw .. i dont think it can be as it would be bloody hot .
if i warm up that area with hair drier the noise almost disappears and the power meter drops a lot .if i freeze cp801s and cp802s the noise starts up again ...
also if i turn the back-lights down the noise lowers quite a bit . brightness affect it slightly too .
tv is le40b650t2w . not that it should matter right now .

manual is here ... https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwiX3OnBhaLRAhXCESwKHcvMC3sQFggaMAA&url=http%3A%2F%2Felektrotanya.com%2Fsamsung_bn44-00264a.pdf%2Fdownload.html&usg=AFQjCNGMd-Too0gZURsIAgmnyO_Ww2TnUA&sig2=50HgdRoJFMZv6D7vC4LMVw&bvm=bv.142059868,d.bGg
p.s i am usually at audiokarma ...

petehall347
01-02-2017, 11:07 AM
well this has got stranger ... been working on it all day and getting no further ahead . mainly reflowing joints and subbing caps .
i decided to try it powered up with my variac as our line voltage is low . set variac to 240v powered the tv on .it seemed to fire up ok until the back-lights came on .then at that point my variac was sounding like a kettle boiling . at this point i switched the variac off quickly .
anyone have any ideas please ? this thing is driving me nuts

petehall347
01-03-2017, 10:20 AM
for anyone in the future this problem is now solved .
i put in another new pfc controller chip fan7530 and the supply is now silent . power draw is normal .