Samsung ln46c630, bn44-00341b, j852

[budm]

Power supply/inverter board BN44-00341B, Jumper J852.
Got this one in today. The backlights flicker. Looking through the thread and found that if the jumper J852 is cut then the problem will go away, but no one indicate what that jumper is for, so I look at the diagram of the BN44-00341B, it does show the jumper J852 (which is normal for most diagram).
I trace out the J852, that jumper is for connecting pin 3 (Emitter of the Photo transistor) of the OPTO PCI801S to the secondary side circuit ground. This OPTO is driven by MM3313 (AC Input/power supply protection) PIN 8 (OUT 2, UVLO_INV), DET2 (PIN3) of the MM3313 is the detection of the output Voltage of the PFC output Voltage. So by cutting the jumper, the protection circuit is removed.
I try searching for the SAMSUNG service bulletin about cutting the jumper wire but did not find any official document from SAMSUNG. It seems to me that this is not really a fix, it is a removal of the protection circuit. The TV was work fine for the owner since 2010, so something must have changed or drift to cause the false protection to cut in and out which cause the flickering of the backlights. If I turn down the backlights level to about 1/4 of the max, then it does not flick. I did not have the times to do more in-depth troubleshooting to find the true cause of the problem yet.
I noticed that the PFC Voltage booster is about 347VDC which seems low to me, the DET2 (PIN3) of the MM3313 is the detection of the output Voltage of the PFC output Voltage. I think there is problem with the feedback circuit feeding pin 1 of the PFC ICP801.

[victor_cj]

Re: Samsung ln46c630, bn44-00341b, j852

PFC does not work well. Check/replace RP802, RP805, RP807, RP810. Check/replace ICP801.

[whatusername]

Re: Samsung ln46c630, bn44-00341b, j852

budm i searched but this is the best i can find but apparently that jumper is one they missed at the factory


Expert: Electra-Tech replied 3 years ago.
If you get the back off look at the power supply. You will see a 46" stamped into the board in the upper left hand corner. Just to the right you will see a control with white glue on it. Know look straight down a inch or so and you will see a jumper MARKED JP852. This is a jumper wire. You need to cut this jumper with the wire cutters. Make sure it is cut and it not shorting up against anything after you cut it. After you cut it reassemble the tv and your fixed. Saved you 100-150 dollars or more.




Expert: Anthony F. replied 3 years ago.
I am a Samsung Fact Authorized servicer I am unframilar with what the expert was talking about I will see if I can find something on it and let you know
Replacing the board will fix the backlight flickering


Expert: Anthony F. replied 3 years ago.
The procedure he mentioned is valid




Expert: Electra-Tech replied 3 years ago.
The Samsung bulletin for this panel flicker is under tips using this customers model number on the GSPN Web site under knowledge tab. I see no way to down load the .pdf file for you here on this service for you to see.

[budm]

Re: Samsung ln46c630, bn44-00341b, j852

"budm i searched but this is the best i can find but apparently that jumper is one they missed at the factory" I doubt that it was missed at the factory sinc eht TV was working fine for 5 years and start having the problem until now, Beside no one on those links never say or explain what the jumper is for that us why I trace out the connection which it turns out to be the protection circuit to detect Low PFC boosted Voltage, so basically, the circuit protection is disconnected.
So if SAMSUNG actually recommended to cut that wire off for the protection circuit, then that to me it is not a really the proper fix and can be dangerous but hey take the risk and hope that the TV will die long before something bad really happen.
The OPTO and the protection ICs are installed for reason, it is not like something that the factory can forget.
It is not like jumper is put in during test and calibration and must be remove after the test is done, that jumper is part of the protection circuit.
I sure like to see the official SAMSUNG Bulletin.

[whatusername]

Re: Samsung ln46c630, bn44-00341b, j852

ok was just trying to help... mayb someone on here has access to the GSPN website and can get u the bulletin

[budm]

Re: Samsung ln46c630, bn44-00341b, j852

I am just trying to understand why after five years the problem just started it.
I do notice one thing is that if I set the backlights to very low level, the backlights will stop flickering which kind of pointing to me that some thing in the circuit cannot handle high current due to low boosted Voltage.
I think if SAMSUNG says that all you have to do is to disable the protection circuit then the flickering will stop, when people see that it will make people ask as to why I will want to disable the protection, will it be safe.
It is like when people say to short out the timing cap in the PWM protection circuit in Sharp TV due to bad lamps so the backlights will stay on.

[budm]

Re: Samsung ln46c630, bn44-00341b, j852

Correct way of fixing the problem instead of cutting out the jumper which is part of the protection circuits.
https://www.badcaps.net/forum/showth...d=1#post589985

[CapLeaker]

Re: Samsung ln46c630, bn44-00341b, j852

I haven't had a TV here that experienced that problem, but I have read about that problem a while back. Some articles were probably the same than in post #3. I also had figured out back then that cutting the jumper is actually bypassing the protection circuit and left it like that. I figured it had something to do with the PFC voltage, but since I never actually had to repair one like that, I had nothing to go by in order to say, o.k. I have low PFC voltage, etc.
Something happened to cause the PFC to go low. Bad cap? any resistors that went high in value?
I wondered a couple of times what happened to this particular problem, so I am watching with interest this thread.

Bad resistors... makes sense.

[budm]

Re: Samsung ln46c630, bn44-00341b, j852

Those 4 resistors (1.5M, RP802, 805, 807, 810) and the 39K RP819 form the Voltage divider for the feedback for the PFC circuit to maintain the output Voltage, if the resistance of the top resistor strings goes down then the Voltage on RP819 will go up so it will make the PFC Voltage to go down.
If the resistance of RP819 goes up, it will also have the same effect.

[neilc6]

Re: Samsung ln46c630, bn44-00341b, j852

I have a Samsung LN40C530 (LN40C530F1FXZC) with reported flickering that I couldn't reproduce after a couple of hours on. Power supply is BN44-00417A. Voltage on the big filter caps is around 360VDC. 1.5M ohm resistors RP802, RP805, RP807, and RP810 have the same designators on this board. I believe they are 1206 size (1/4 watt) so I'll order them and see if the voltage goes up. RP819 measures about 40.3K in circuit which could also be pushing the voltage down.

[dskall]

Re: Samsung ln46c630, bn44-00341b, j852

Correct way of fixing the problem instead of cutting out the jumper which is part of the protection circuits.
https://www.badcaps.net/forum/showth...d=1#post589985

The post #12 from SADDLE AU is correct about not replacing string with just one resistor because of the voltage? As I wondered why there where 3 or 4 in series.

[budm]

Re: Samsung ln46c630, bn44-00341b, j852

The post #12 from SADDLE AU is correct about not replacing string with just one resistor because of the voltage? As I wondered why there where 3 or 4 in series.

The resistor has breakdown Voltage spec so to be safe they put bunch of resistor in series, the board contamination and moisture also affect the breakdown Voltage, that is why you will see they use a bunch of resistors connected in series in the high Voltage section.
BTW, when I said the correct way of fixing is to replace the resistors in the string with the new one instead of cutting the jumper, not meaning to use 1 resistor to replace the whole string, the breakdown Voltage should be twice the operating Voltage to be really safe..

[budm]

Re: Samsung ln46c630, bn44-00341b, j852

I have a Samsung LN40C530 (LN40C530F1FXZC) with reported flickering that I couldn't reproduce after a couple of hours on. Power supply is BN44-00417A. Voltage on the big filter caps is around 360VDC. 1.5M ohm resistors RP802, RP805, RP807, and RP810 have the same designators on this board. I believe they are 1206 size (1/4 watt) so I'll order them and see if the voltage goes up. RP819 measures about 40.3K in circuit which could also be pushing the voltage down.

It does not take much variation of the resistance of RP819 to affect the output Voltage, some of the I see they use two resistors in parallel to get the correct output Voltage.

[dskall]

Re: Samsung ln46c630, bn44-00341b, j852

So a smps with pfc should it always be around 390v boosted or are they different. Do you look at main cap voltage to get idea of what voltage it should be.

[budm]

Re: Samsung ln46c630, bn44-00341b, j852

390V is the typical value, the cap is only rated at 450V, so that will give about 60V margin.

[dskall]

Re: Samsung ln46c630, bn44-00341b, j852

I have a board out of a vizio FSP155-2PSZ01. Main cap measures 350v but cap rating is 400v. So 350v should be a good pfc voltage on this board?

[budm]

Re: Samsung ln46c630, bn44-00341b, j852

That is on a low side and depend on the power supply design but since the cap is only rated at 400VDC then 350V is probably OK. Some TV power supplies do not have low PFC Voltage shutdown circuit so the AC input current will be higher than normal when PFC is low and it may blow the main fuse or cycling on and off. Most SAMSUNG have low PFC Voltage detection.

[dskall]

Re: Samsung ln46c630, bn44-00341b, j852

Where do you think it should be with a 400v cap?

[budm]

Re: Samsung ln46c630, bn44-00341b, j852

350~360 range.
You can also put full load on it by turning up the backlights to the max and run it for a while, you can also monitor AC current the TV is drawing too.

[dskall]

Re: Samsung ln46c630, bn44-00341b, j852

Thanks for sharing knowledge. Learning a lot.