bn44-00808e Power supply problem

[CherM]

I'm an electronics novice with a bad power supply on a samsung tv. The power supply is bn44-00808e

The tv was in storage for 3 years. It worked for an hour or so. While watching it, it suddenly rebooted and kept cycling to reboot the tv maybe a second after starting to reboot. This caused a clicking sound, like a relay for about 10 cycles. I quickly unplugged the tv. I waited a minute and plugged it back in again. No standby... nothing.

After disassembly, and a visual inspection, I saw nothing unusual. The board looked like new. All the caps were physically intact. I tested the on board fuse. It was blown, 120v ac across it.

I disconnected the two harnesses attached to the power supply and soldered a jumper across the fuse, using a glass buss fuse holder and the closest thing I had to the 8A on board fuse, a 10A. I was standing by with a laser IR thermometer hoping to see find any excessive heat buildup, but within 2 seconds the fuse smoked. A small coil next to the line input read about 5 degrees above ambient. The rest was of the board was cold.

I'm not sure what else I can do, short of pulling all the caps from the board and checking them. I'd appreciate any help.

[nomoresonys]

Re: bn44-00808e Power supply problem

simple dim bulb tester to keep from blowing components up: https://www.youtube.com/watch?v=wRFRwOnLsZI

[diif]

Re: bn44-00808e Power supply problem

Check the components under the heatsink for shorts. Bridge rectifier and a couple of mosfets.

[nomoresonys]

Re: bn44-00808e Power supply problem

simple checks, with tv UNPLUGGED from power, start on top of board, check all the diodes and resistors, also check ALL transistors, they are labeled starting with Q, see if any of the 3 pins are shorted to either of the other 2 pins of the component.

[nomoresonys]

Re: bn44-00808e Power supply problem

not sure how you tested your fuse, a simple way is set meter to continuity mode, if the fuse shows continuity its good. should use the same type fuse that it came with.

[nomoresonys]

Re: bn44-00808e Power supply problem

or just see if that will work if you prefer: https://www.ebay.com/itm/28483890523...Bk9SR9qY48fFYQ

[CherM]

Re: bn44-00808e Power supply problem

not sure how you tested your fuse, a simple way is set meter to continuity mode, if the fuse shows continuity its good. should use the same type fuse that it came with.

While plugged in, check voltage across fuse. If it's blown it will read with voltage. If it's good, volts should be zero.

[nomoresonys]

Re: bn44-00808e Power supply problem

ok, I would build that simple dim bulb tester which saves from blowing up components, nothing worse than that, specially when you have to wait for them to arrive and get some of the proper fuses and test those components in post #4.

[nomoresonys]

Re: bn44-00808e Power supply problem

it does matter what kind of fuse you use a T represents a slow blow fuse, meaning you would need that kind of fuse, using 10 instead of 8 shouldnt be a big deal but you shouldn't go under 8.