Samsung LN46B500P3F

[_N_]

Re: Samsung LN46B500P3F

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[budm]

Re: Samsung LN46B500P3F

No PFC IC with that P/N that I can find.

[_N_]

Re: Samsung LN46B500P3F

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[budm]

Re: Samsung LN46B500P3F

7 pins all read 5.16 Vdc
the 8th back pin reads 12.6 Vdc

What did you use for GND pin, the chassis or the negative leg of the main filter cap?

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Re: Samsung LN46B500P3F



I apologize you were correct. measuring now.

[_N_]

Re: Samsung LN46B500P3F

pins 1-4 measures 75.8 vots
8 pin measures 65.2 volts

measured to chassis ground.

[budm]

Re: Samsung LN46B500P3F

OK, the readings are wrong because you are working in the primary side circuit, the GND ref for the meter will be the negative leg of the main filter cap not the chassis GND (CHASSIS GND can be used for GND ref for the cold secondary side of the power supply).
The GND pin of the PFC IC is also connected to the Negative leg of the main filter cap but i would suggest you to use the negative leg of the cap instead in case the probes slip on you.

[_N_]

Re: Samsung LN46B500P3F

Measuring from the main 2 filter caps laying on there sides there NEGATIVE lead to the 8 pins on the pfc With the TV on.
gives
1: 0.97V --- 8: 14.6
2: 0 --- 7: 0
3: 0 --- 6: 0
4: 0 --- 5: 0

[budm]

Re: Samsung LN46B500P3F

OK, 14.6VDC on VCC pin is good (minimum Vstart is 12VDC but no action on the Gate drive pin at all.
We need to check more parts in the PFC section:
Diode DP804, 805, 806
Resistors RP801
I believe you already check the fuse FM801S?

[_N_]

Re: Samsung LN46B500P3F

OK, 14.6VDC on VCC pin is good (minimum Vstart is 12VDC but no action on the Gate drive pin at all.
We need to check more parts in the PFC section:
Diode DP804, 805, 806
Resistors RP801
I believe you already check the fuse FM801S?

Diode:
DP804: in diode check sends voltage 1 way ,running 150V through it
DP805: in diode check sends voltage 1 way ,running 150V through it
DP806: in diode check sends voltage 1 way ,running 150V through it
Resistors:
RP801: 50

fuse FM801S: checks good not blown up

[budm]

Re: Samsung LN46B500P3F

Do you mean it shows 0.150V on the meter in Diode, not 150V?
But any way, I am looking for shorted out Diodes, but they are OK.
I would try new IC at this points since it will take me lots of times to trace out the circuits.

[_N_]

Re: Samsung LN46B500P3F

Do you mean it shows 0.150V on the meter in Diode, not 150V?
But any way, I am looking for shorted out Diodes, but they are OK.
I would try new IC at this points since it will take me lots of times to trace out the circuits.

Its not the diodes.
I pulled them out about a week ago and tested them out of circuit.
along with all fuses, and resistors I checked there color codes to see if they were in spec ;}The through hole stuff.
Its the simplest thing to check with a meter. I have one of those little ebay component checker things with a LCD.
Its the ICs that drive me nuts not to mention the teeny tiny laser etching on them.
But im learning ones never to old, to keep at it.
Besides its not all lost, others will read your posts and my electrocution an learn how to test a psu.

Next? at your leisure of coarse.

[budm]

Re: Samsung LN46B500P3F

Lets try resistance test on the IC, Check the resistance of all the pins against GND pin to see if the readings will give us a clue.

[_N_]

Re: Samsung LN46B500P3F

will do, tomorrow first thing. :}
its 1 AM here.

[_N_]

Re: Samsung LN46B500P3F

Bud I went back and added a little solder to the fets and I got an interesting affect now, similar to what you wrote in another posting.

Now, when I turn it on the back lights turn on for a second and turn off and recycle repeatedly with the PSU the relay can be heard clicking in conjunction with the lights.
So I pulled everything off AGAIN and measured and Again everything appears not to be blown, Nothing seems shorted. No bubbles on the chips
no tiny burnt holes. Could the components be breaking down when in use becoming "leaky"?

I then Pulled off the motherboard cables and plugged her into the Ac outlet and the lights "come on" woohooo:} for a brief second then stay off ahhhh dammit :{ .

I got the idea from this posting you made:

" : BN44-00265A schematic needed:
It is strange that the backlights will flash 4~5 times in sync with cycling on and Were those two MOSFETs failed as shorted?
BTW, the PS_ON and the Inverter ON/OFF pins have pull-up resistors, so if you disconnect the cable between the power supply/inverter board board, the back lights should come on the minute you plug the TV into the AC outlet."

[budm]

Re: Samsung LN46B500P3F

Right now the main thing is that when you power on the power supply board by itself, the relay should stay on since the board has built-in pull up resistor for the PS-ON pin, so then the PFC Voltage should be >360VDC, that is what we need to get it going first.

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Re: Samsung LN46B500P3F

Bud Id like to thank you, For all your help.
It was and is genuinely appreciated.

I ended up selling the 46' tv for its lcd panel to a local Tv repair shop ( joys of Craigslist ,wasn't even looking and they had an add. For a "Sammy 46 lcd wanted" $120.00. sweeet)
I didn't need it, Ive got a spiffy samy super thin on the wall.
!! BUT before I left I saw a pro-scan plded3996a-c2 on the floor they let me have freee.
Annoying questions will be coming with pics!