Samsung UN55C6300SFXZA blowing fuses

[EGreen]

Hello, I have a sumsung UN55C6300SFXZA with a BN44-00358B/PD55AF1U ZHS
Power supply board. The guy I got it from said it just went out one day. When I opened it up I found the ceramic cap in location CP808 had been replaced with a RR 221K 1KV 3D . The original was R 221K 1KV. I don't know if this makes a difference. Looks as if the original one exploded due to the burn spot and smoke residue. The fuses were blown, I replaced them, Unplugged all connectors, powered up 120v ,fuses held, no power at the rectifier,plugged in connector to main board, fuse blew.I'm going to get some more fuses today.When I get back I'll use my limited skills to check some more components.
What would I look for next?
I have a mid grade DMM with capacitance testing and I orderd this "Small 12864 LCD Transistor Tester Capacitance ESR Meter Diode Triode MOS LCR NPN (251518131978)" .Don't know if it will work by it's worth a try

I am not well educated in electronics , Can someone point me in the right direction to learn how to trouble shoot and repair these type of boards?
I paid for an online site to learn but all I got was links to more paid sites.
Is there a good source for training on how to troubleshoot and repair these TVs?
I want to learn about the different sections of these board and how to test/repair them.

[EGreen]

Re: Samsung UN55C6300SFXZA blowing fuses

These are from Shop Jimmy

[EGreen]

Re: Samsung UN55C6300SFXZA blowing fuses

I have 5.2 vdc on pin 16 CNM801. When I jumper to pin 18 pwr on/off both fuses blow immediately.

[budm]

Re: Samsung UN55C6300SFXZA blowing fuses

There are 4 fuses on the board, which are the two that blown? The main AC fuses?

[EGreen]

Re: Samsung UN55C6300SFXZA blowing fuses

Yes ,the other 2 are good

[freakaftr8]

Re: Samsung UN55C6300SFXZA blowing fuses

odd I would look for shorted MOSFETs and me 12 volt and other output voltage circuit in the secondary side of the power supply to start.

[EGreen]

Re: Samsung UN55C6300SFXZA blowing fuses

Thanks, I'll Check them out of circuit tomorrow.

[budm]

Re: Samsung UN55C6300SFXZA blowing fuses

So both 5A main fuse is blown when PS_ON command is inserted.
That is an active shorts, not static shorts, so we need to find out if there are parts that is now damaged.
You should check the RESISTANCE on the Source and Drain of the power MOSFETs
QP801, 802 in the PFC Voltage booster circuits, that cap CP808 is the snubber cap for the Diode DP802, 809.
QM801, 802 for the VDRIVE SMPS power supply for the LED backlights circuit.
You will need to look up the info on the MOSFET, look up the spec sheet of the P/N of the MOSFETs to get the pinout.

[budm]

Re: Samsung UN55C6300SFXZA blowing fuses

You should build one of this BOX which basically put the 120V lamp in series with the load (the TV or what ever you are working on) to automatically limit the current if there is shorts circuits so you do not keep blowing the fuses and parts.
You should also use the GFCI outlet to protect yourself.
http://s807.photobucket.com/user/bud...in=true&page=1

http://s807.photobucket.com/user/bud...tml?sort=3&o=7

[EGreen]

Re: Samsung UN55C6300SFXZA blowing fuses

Thanks Budm ,Will do tomorrow...I am an electrician and have parts to build something similar to that.

[EGreen]

Re: Samsung UN55C6300SFXZA blowing fuses

I found a shorted mosfet
QP802
STF13NM60
I ordered 4 from arrow and some of the correct capacitors to replace the non-matching one that some stuck in there.
I also made a dim bulb tester like Budm suggested. The lamp is in line with the nuetral side of the duplex receptacle to prevent shock from the shell of the socket and the gfi is before the lamp so I can use it for full power.

[EGreen]

Re: Samsung UN55C6300SFXZA blowing fuses

Update, Changed out shorted QP802 and and also 801 just in case. The TV powered up and works fine . The shorted QP802 apparently took out the replaced diode CP808 . Thanks for your help. One more thing, When I first powered it up there was green lines and patches all over the screen. I reset all the ribbon cables in the connectors on the T-Con board and that fixed it...E

[budm]

Re: Samsung UN55C6300SFXZA blowing fuses

Well done and thanks for the follow-up on the repair.