Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

[popel75]

Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

Thanks !! It says 110 V/ 60Hz on the sticker on the back of the TV. I guess I have to remove the back of the TV then to check the power supply board ?
My assumption was that Samsung uses those 110V-240V boards on US and European alike and simply puts stickers that match the domestic voltage on the back of the TV (for whatever reason...)

[budm]

Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

http://assets.shopjimmy.com/media/ca...00811a-top.jpg

According to the input Voltage chart as printed on the board, it show 100 ~ 240VAC.
What does it show on the model number sticker on the back of the TV?

[popel75]

Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

Hey guys newbie question ! I own this TV : UN55JU7100 power supply board BN44-00811A bought in the US. Does the power supply board work with 220V/50Hz power supply ? Thanks for responding if you have a second !

[Louis82]

Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

UPDATE: Tv is Fixed!

@Budm : Yes, The diode blew as soon a I plug the power cord in.
So, The problem were the 30 Diodes I ordered from a vendor at AliExpress.
I got some new ones from an eBay seller in California and my power board / Tv worked again. Phewww - As always I learned a lot from this. I wish I had to do troubleshooting everyday, so much to learn.

Thanks Budm!

[nomoresonys]

Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

For Fallindeep if your still looking, horizontal waves can be a panel issue, see if this video helps. https://www.youtube.com/watch?v=yTnkOfwBGGE

[budm]

Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

BTW, the bridge rectifier still tested OK? since it is basically connected in series with that PFC diode.
Also, did the diode blow up right away by just applying the power without hitting the power switch?

[Davi.p]

Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

Not good hijack other's thread with different problem.

[Louis82]

Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

I think I figured out. I found a good board that uses the same Diode, I removed it from board and the measuring is different to my "new" diodes from Aliexpress.

Here measures (good diode):
Pin 2-1: 1.6Mohms
Pin 2-3: 1.6Mohms

Aliexpress Diode:
Pin 2-1: 7.81Kohms
Pin 2-3: 7.81 Kohms.

No good, right?

Did i order the right part number? SF10A600HPI . Does the number on top AUK D5223 matters?

These diodes are bad. Im gonna remove these filter caps.

[budm]

Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

Well that does not make sense that the diode will blow up with that high of the resistance, too much current had to be so high that it causes the diode to shorted out. I am surprised that the main fuse did not blow either.
2V may be enough to fool the Ohm meter.

[Louis82]

Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

Good board - Filter cap checks 0 ohms and 2V DC
Bad board - Filter cap checks 4 mega ohms and -0.3 V DC

[budm]

Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

4 millions Ohms? and 0 Ohms on the good board?
Check the DC Voltage on the main cap to see if they are completely discharged or not.

[Louis82]

Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

Yes new diode on the board check less than 1 ohm. I have 30 of these crapy diodes. I made te comparison above with one unused diode.

Now this is strange, filter cap on board checks 4.0 mohms - While the good board where I grabbed the good diode for test, checks 0 ohms. They both have been unplugged for while - are they still discharging?

[budm]

Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

'SF10A600HPI' see the spec sheet I provided.
So did you check the resistance between the two legs of the main cap?
But I though you said the new diode is blown. is it showing < 1 Ohm now?

[Louis82]

Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

I think I figured out. I found a good board that uses the same Diode, I removed it from board and the measuring is different to my "new" diodes from Aliexpress.

Here measures (good diode):
Pin 2-1: 1.6Mohms
Pin 2-3: 1.6Mohms

Aliexpress Diode:
Pin 2-1: 7.81Kohms
Pin 2-3: 7.81 Kohms.

No good, right?

Did i order the right part number? SF10A600HPI . Does the number on top AUK D5223 matters?

[budm]

Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

Here is a pic of Diodes. Left side is the original one.
Please tell me they are not the same. I need a reason to understand this.

So if you check the resistance between the center pin against the two outside pin, the reading shows <1 Ohm? It is a dual
As I indicated, for that diode to short out the Cathode must be seeing the very low resistance to GND, that is why you need to check the resistance between the two legs of the main filter cap, and should have caused the main fuse or the NTC to blow.
As you can see in the circuit I provide you can see the current path through that diode.

[Louis82]

Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

Here is a pic of Diodes. Left side is the original one.
Please tell me they are not the same. I need a reason to understand this.

[Louis82]

Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

Correct, MOSFETS still measuring fine. Diode is shorted. Replaced with exact part number. Wonder if this Diodes are chinese fake components.

[budm]

Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

The two MOSFETs QP801, 802 did not blow?
Did you replace that Common Cathode DP807 with the exact same type and isolated case?
For that PFC Diode to blow, the Cathode must be seeing very low resistance to GND.
See the diagram showing how that diode being used in the dual PFC circuit.
Check the resistance between the two legs of the main filter cap CP810 or 814 to see what you get.

[Louis82]

Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

Replaced PFC IC SPC1012T and the same, diode location DP807C keeps blowing.

[Louis82]

Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

I found NT811 cracked, replaced all burned parts except PFC Ic and still the same.
Last try will be the PFC IC but I can't tell the part number of it.