Samsung LE32R88BD/ BN44-00155A

[vinceroger69]

Re: Samsung LE32R88BD/ BN44-00155A

with diodes that read odd its always a good idea to remove and retest you can also just lift one leg of the pcb retest.

[Agent24]

Re: Samsung LE32R88BD/ BN44-00155A

Well my set has crapped out again, as a refresher it is a Samsung LN3253HX with the BN44-00155A board.
Since the cap, fuseable resistor and mosfet replacement it has been golden. I am gone frequently for extended periods so I unplug the set each time.
This time I heard a soft pop, much like when you plug in a power supply for a Macbook, when I plugged it in but everything worked fine for a couple of day. When I turned it on last everything started as normal (set had been plugged in for 48 hours) when all of a sudden the set went dead, not even a standby light.
I looked over the board and couldn't see anything so out came the meeter. So far I have only found an oddity on diode DB851. I'm getting a reading in both directions (sorry, didn't write down the value) but when removed from the board it tests fine.
Is this normal or do I have something else I should be checking.
Photo is not of my board but of the right model.

I assume you have checked the parts you replaced last time?

We need a better photo too, of your own board. A tiny photo of someone else's board doesn't help much.

Might help as well to show where DB851 is too? Is there a schematic on here for your set?

[vinceroger69]

Re: Samsung LE32R88BD/ BN44-00155A

This should be the right one budm posted it in a earlier post

[Agent24]

Re: Samsung LE32R88BD/ BN44-00155A

If DB851 tests OK out of circuit then I guess it's OK.

I assume you get no output on ST/BY rail? Should be 5.2 volts.

Do you get any power to CP803 (Main filter capacitor?) - should get rectified line voltage there, about 160v-170v without the PFC on.

If you do have right voltage on CP803, check power to Pin 5 of ICB801S and Pin 1 of TB801S.

[dsc]

Re: Samsung LE32R88BD/ BN44-00155A

Vinceroger69, I did pull it and test, checked ok. Thank you for the sch, I've been on the thread before but forgot it was here.
Agent24, I'm on the road right now, will post a better shot when I get back. Had checked majority of the board (everything I had replaced before included) statically, ran out of time to check it powered.
Will check the point you listed.
Thank you for the help!

[dsc]

Re: Samsung LE32R88BD/ BN44-00155A

On SCH, DB851 is on page 1 area 7/D, in line with standby 5.2v

[vinceroger69]

Re: Samsung LE32R88BD/ BN44-00155A

Vinceroger69, I did pull it and test, checked ok. Thank you for the sch, I've been on the thread before but forgot it was here.
Agent24, I'm on the road right now, will post a better shot when I get back. Had checked majority of the board (everything I had replaced before included) statically, ran out of time to check it powered.
Will check the point you listed.
Thank you for the help!

sorry i missed the bit where you said you had actually checked the diode of the board.

[dsc]

Re: Samsung LE32R88BD/ BN44-00155A

Had enough of searching for the problem so I picked up a power board on ebay for $28 total.
Works perfect so worth the savings in time alone.
Now I have a board I can pull apart and learn on.

[Agent24]

Re: Samsung LE32R88BD/ BN44-00155A

Good to hear it. Best part is if you have a working board you can compare voltages between them. It may help you find the fault even faster

[darthyoda]

Re: Samsung LE32R88BD/ BN44-00155A

Add me as another person that replaced the RM801 FR, and brought life back to Samsung LNT3253H containing this power supply board, as per...

https://www.badcaps.net/forum/showpo...2&postcount=60

[microso]

Re: Samsung LE32R88BD/ BN44-00155A

Hi,...
I manage to revive my tv set LE32R88BDX, after i read this thread.
Thx again to all for your advices.
I just remove the glue from the QM802 and reuse, RM801 is toasted and i use one 0,22R 1/4 W for testing, all its ok.
I cant find until now one 0,22R 1 W fusible resistor, and question is if i can use another one.
Any hint value and power (0,1R , 0,3R , 1/2 W, 2 W)?
Now its the T220 monitor my next target, no power at all, and i hope to find the fuse burned,..
Cheers.

[darthyoda]

Re: Samsung LE32R88BD/ BN44-00155A

I popped in the MOX resistor (non-fusible) listed below, and it has been working perfectly for over a month now...

http://www.digikey.ca/product-detail...0TR-ND/2021716

[microso]

Re: Samsung LE32R88BD/ BN44-00155A

Hi,
I manage to find one 0,22R 1W fusible resistor for my tv (buying 5 pcs.. )
The issue with my T220 is no power (300 DC voltage across the 100uf 450V main cap and low voltages to CN2).
I have 2 caps C301 and C302 bloated, and i replaced with 2x 1000uF 25 V.
Again, no power led light, and i start to check the D104 and D105. D104 shows continuity between the anode 1 and the cathode and i replace.
Now my T220 is working again.
Thx again to all for sharing.

[JDC]

Re: Samsung LE32R88BD/ BN44-00155A

I've got the same set, RM801 confirmed bad. Replaced, all OK.

[paul85]

Re: Samsung LE32R88BD/ BN44-00155A

What causes PFC to not work? I'm working on a similar board, not for this model samsung, but for another, and only get 160 volts at the 3 main PFC caps instead of 400 volts. I replaced two fets that were bad which stopped my fuse from blowing, but when jumping pson with a 470 ohm resister, I only see 160 v at the pfc caps. I've posted for the past couple weeks in my other thread, but it doesn't have the traffic this one does so I'm hoping someone can answer as to what else I can look at.

[Agent24]

Re: Samsung LE32R88BD/ BN44-00155A

When MOSFETs short they often short to the gate as well, meaning that 160v from the mains goes straight into the gate drive circuitry and kills it.

Check the IC and parts driving the MOSFETs

[paul85]

Re: Samsung LE32R88BD/ BN44-00155A

When MOSFETs short they often short to the gate as well, meaning that 160v from the mains goes straight into the gate drive circuitry and kills it.

Check the IC and parts driving the MOSFETs

Ah, I have checked the surface mount resistors in series and everything else I can check like diodes, etc without a scope, but I have no way of checking the IC. I might just buy a replacement kit for this PS and replace all of the ICs that come with it and see if that solves the problem. My PS is a BN44-00445A and there is a kit online that comes with 3 ICs I could replace.

[jetadm123]

Re: Samsung LE32R88BD/ BN44-00155A

Ah, I have checked the surface mount resistors in series and everything else I can check like diodes, etc without a scope, but I have no way of checking the IC. I might just buy a replacement kit for this PS and replace all of the ICs that come with it and see if that solves the problem. My PS is a BN44-00445A and there is a kit online that comes with 3 ICs I could replace.

You can try some basic checking of the pfc chip:

1) with power disconnected, try measuring the resistance between the Vcc and ground pins to see if it's shorted internally.

2) with power connected, measure the voltage of the Vcc pin. There should be a minimum startup voltage for that chip to operate properly.

[pitbull2510]

Re: Samsung LE32R88BD/ BN44-00155A

Hello everyone I have here such a power supply bn44-00155a in which all the voltage pulses pulsate, until it was found that there were swollen electrolytes cm851 and cm852 after the replacement noticed the pulsation sinned on the optocoupler checked all 4 and all 4 working and then replaced the resistor rm801 it also is the fuse including changing cp801 db851 dzm854 qm801 qm802, dm801 dm802 tested a large electrolyte cp803 but it is normal. Stress all normal but throbbing I do not know where to further dig help guys

[rgreair]

Re: Samsung LE32R88BD/ BN44-00155A

Hi, i'm new, I have the same board for the 32inch model, had a bad capacitor 10v 1000uf replaced this and would not turn on, i tried the things mentioned in this post,. on its own it will turn on after 15 minutes, resistor in rm801 checks out fine, capacitor cm861 had blown cap. replaced this. 24 volts fluctuating around 12 to 17 volts and slowly goes up to past 24 volts then tv turns on, this is on cm802 (s) any ideas on this. previous own used tv for cctv and was on until a power cut. does work fine after its been trying for 15 minuets.