Samsung un58h5202af no power..no clicks or lights

[jackfish]

Have a Samsung here that seems dead.. checked the power where it says standby it only reads at 1.8 volts no visible sign of bad caps on board..output to video board is also 1.8..

[dskall]

Re: Samsung un58h5202af no power..no clicks or lights

What is voltage across your main cap?

[jackfish]

Re: Samsung un58h5202af no power..no clicks or lights

Other pic

[budm]

Re: Samsung un58h5202af no power..no clicks or lights

Any good clear pictures of the whole back side of the TV showing all the board?
Pictures of the whole power supply board?
Power supply board P/N BN44-???????

[jackfish]

Re: Samsung un58h5202af no power..no clicks or lights

Power supply bn44-00787a Have to get another pic..

[budm]

Re: Samsung un58h5202af no power..no clicks or lights

So if you disconnect the cable between the power supply board and the main board then power up the power supply board, what DCV do you get on jumper J846?

http://www.shopjimmy.com/catalogsear...?q=bn44-00787a
Pictures provided by shopjimmy. BN44-00787a

[jackfish]

Re: Samsung un58h5202af no power..no clicks or lights

1.8vdc..when I prob the fuse it's giving me 28vac

[budm]

Re: Samsung un58h5202af no power..no clicks or lights

1.8vdc..when I prob the fuse it's giving me 28vac

Which fuse? The main AC fuse in the hot side? 28VAC cannot be right. Where did you put the leads of the probes to read that 28VAC?

[jackfish]

Re: Samsung un58h5202af no power..no clicks or lights

Took the board off..probed it from underneath..getting 123vac on the fuse..put the negative probe on the chassis top left corner by the three caps under the stb 8v ..still reads 1.8vdc..does the board need to be jumped to get a reading?

[budm]

Re: Samsung un58h5202af no power..no clicks or lights

Took the board off..probed it from underneath..getting 123vac on the fuse..put the negative probe on the chassis top left corner by the three caps under the stb 8v ..still reads 1.8vdc..does the board need to be jumped to get a reading?

How did you go about measuring the AC Voltage on the fuse, where did you put the two meter probes? When check the incoming AC in the hot side you do not use chassis GND. You put one probe on Neutral and another to check each end of the fuse.

[budm]

Re: Samsung un58h5202af no power..no clicks or lights

The 8VDC Standby should be present the minute you apply 120VAC to the power supply board.

[jackfish]

Re: Samsung un58h5202af no power..no clicks or lights

Nope..no 8v..i checked a different tv to see if my multi meters working.. was getting 12v at places where it was suppose to be...

[budm]

Re: Samsung un58h5202af no power..no clicks or lights

At this point I cannot tell if you are getting 120vac to the bridge rectifier or not, so another way to find out is to check the DCV between the two legs of that black cap laying on its side to see if you have about 160vdc or not, or buy new board if you cannot troubleshoot down to component level.
BTW, you can do SMD device removal/installation, right?

[jackfish]

Re: Samsung un58h5202af no power..no clicks or lights

The big cap is kicking out 170vdc...i can do soldering anremoval..im trying to post a pic but for some reason it won't let me..the small transformer on the cold side looks discolored around it..

[jackfish]

Re: Samsung un58h5202af no power..no clicks or lights

Area looks heated...

[budm]

Re: Samsung un58h5202af no power..no clicks or lights

Area looks heated...

That section is the Voltage Boost Converter for the Backlights LEDs.
So you do have the main DCV to run the primary drive circuit.
At this point start by checking those black rectifier diodes in the cold side to make sure they are OK first, you have 9 of them.
BTW, there is SMD Power MOSFET on the bottom side of the board where there is sign of heating, check and see if that MOSFET Q9101? is OK or not.

[jackfish]

Re: Samsung un58h5202af no power..no clicks or lights

Piped off one leg on each diode to test.. .they only read in one direction...the mosfet under the burn reads at both legs.. all others read only on the right leg..took it off the board to make sure..

[jackfish]

Re: Samsung un58h5202af no power..no clicks or lights

Replaced that power mosfet ..picked one off a 55 inch Emerson tv that had a broken screen..working for five hours so far....wonder if heat killed that chip..

[Jeff Pepin]

Re: Samsung un58h5202af no power..no clicks or lights

hi , ive read this thread is resolved , i have this tv , mine blowed main psu fuse , blowed 2 smd switching mosfet st14n50n wich i replaced by 2 21NM60N to-247 ,added some hole to the board to fit them and 2 small heatsink ( just to be sure), tested it with a 3A fuse insead of 5 to let anychance if the primary goes wrong ,and cap filled up , primary circuit are alive but no standby , after some visual inspection , i have find ICM871 chipped out (circled in red on the budM pic ) the only thing left its the dye , did anyone can help me to find the value of this transistor , maybe if im lucky , its the same as icm801 marked 3A ( circled in yellow ) , but , can't moove without be sure
thanks

[Jeff Pepin]

Re: Samsung un58h5202af no power..no clicks or lights

he! good news!! ( At least for me)

a friend have same tv and it permitted me to take an eye on his psu board , found that ICM871 is the same as 801 , marked 3A , and look like general pnp transistor with first finding ,. lets hope mainboard are ok lol