PW.168W2.801 no 5v SB for sharp 55BL5KA TV

[DiamondTech61]

I have a PW.168W2.801 PSU that is getting no power on the 5v SB pin, nothing looks burnt on the PSU itself, I have removed everything and Im getting over 300v on the main capacitor. I have the LED cable connected in the pic but have removed it for testing, any help is appreciated.

[R_J]

It looks like T101 is the standby transformer, which is driven by Q101, there is a pwm ic (u101) that drives Q101, Remove HS5 heat sink and check R148, if it is open, Q101 is likely shorted and U101 and components in the gate drive circuit may also be damaged

[DiamondTech61]

R148 is reading as 000.5 ohms with q101 removed, can test q101? is it a transistor? it looks like it says SVS7N65F
SL9KT0G any help on testing would be great

[R_J]

SVS7N65F is a mosfet, R148 is in the mosfet source pin to hot ground, so I suspect the mosfet is ok.

With all the parts reinstalled check if you have voltage across E106 or to check this voltage place your negative probe of your meter on E201 (-) and your positive probe on D105 cathode, you should have around 25vdc
Can you provide a photo of the back, trace side of the board, especially for the standby circuit area

[DiamondTech61]

E106 keeps jumping 8,9,10,8,9,10v continuously, E201 - to D105 cathode is the same. I did rip the trace on the part i removed but have temporarily put a wire across

[R_J]

Check that you don't have a short on the 5vstby output, check that D101 is not shorted, it is a dual diode so check it in diode mode between center pin and each of the other two pins. D101 actually supplies +12v to that small standup board PWB1 which I believe supplies the standby 5v
J29 should be cold ground and J28 should be +12v check that there is no short between these two jumpers, and if there is no short, check what voltage you get across the two jumpers.
Are you getting any voltage across E107 this is the vcc voltage for U101, there is a zener diode in that circuit, ZD101 and R164, check them R64 should be a low value (a few ohms)

Also, what is the number on U101

[lotas]

Power Supply Sharp PW.168W2.801

[DiamondTech61]

thanks for your help! J28 AND J29 ARE shorted! I cant really see U101 very well but have taken a pic

[DiamondTech61]

GUYS YOUR ARE LEGENDS!!!!!!! Ive sorted it, on the stand up board there a 3 SMD capacitors, one was shorted, Ive removed it and now got 5 and 12v standby! Thank You SO MUCH!!!!!!!!!

[lotas]

I cant really see U101 very well but have taken a pic

OB2273 (OB2273CMP) marking 273**