Problem with Samsung LN32C450E1D

[Karutcha]

Hi,

Model LN32C450E1DXZC

Power led is solid and on. Using remote control or switch give nothing. No sound, no blink from led, no power on screen. Fuse is Ok on power supply board.
Fuse RB803 = 1.02 Ω and RB805 = 10 Ω so It's ok too

TEST 1 :
I disconnected main board (CN201) from power supply (CN802), I disconnected cable from Power supply (CN803) to Driver board.

I measured with a digital meter and i get :

B13V = 3.78Vdc, B5V = 1.66Vdc, AV = 5.30Vdc, PS_ON = 0.74Vdc

TEST 2 :
No cable between Power supply (CN803) and driver board
I connected cable between Power supply (CN802) and main board (CN201)
I disconnected other cables as Main board (CN1302) to TCOM, Main board (CN1202) to speaker, Main board (CN401) to Function board

This time, I've PS_ON = 0Vdc, B13V up and down all the time (0.5 to around 6Vdc), A5V = 5.3Vdc, B5V up and down all the time ( 0.3 to 0.7Vdc)

So whats' wrong, is it main board ? or power supply board ?


Could you help me please ?

Thanks a lot

[tom66]

Re: Problem with Samsung LN32C450E1D

What is BN44 number on power board?
Looks like power board fault. Common issue is low PFC bus caused by shorted diode.

[Karutcha]

Re: Problem with Samsung LN32C450E1D

Power board : BN44-00338B
Main Board : BN96-16387A


I've a schematic for BN44-00338B, if you can help me to find section to test, I will do it.

[tom66]

Re: Problem with Samsung LN32C450E1D

*338B schematic


Check voltage -across- CP801S. Expecting 160V or 320V in standby (+/-10V) and upwards of 385V when powered up.

[Karutcha]

Re: Problem with Samsung LN32C450E1D

Input power is 120Vac

For this measure, all boards are disconnected from power board B44, and I've 390Vdc for CP801S. Configuration as Test1 (B13V = 3.78Vdc, B5V = 1.66Vdc, A5V = 5.30Vdc, PS_ON = 0.74Vdc )

With configuration as Test2 (power board with Main board) : I've an up and down between 360Vdc - 390Vdc (I've PS_ON = 0Vdc, B13V up and down all the time (0.5 to around 6Vdc), A5V = 5.3Vdc, B5V up and down all the time ( 0.3 to 0.7Vdc))

[tom66]

Re: Problem with Samsung LN32C450E1D

OK, that indicates PFC is OK (PFC ripple may be OK when in standby.)

Check voltage across CB802, CM807.

[budm]

Re: Problem with Samsung LN32C450E1D

The 24V must be bad also then since the 13V and the 24V are generated by the same circuit. Check the Blue cap CM808. This power supplyis know to have bad cap CM808 and the SMPS IC ICM801.
The PS_ON should be >2VDC since it has built-in pull-up resistor using the 5VSTBY. Please verify that reading.

[Karutcha]

Re: Problem with Samsung LN32C450E1D

For Tom66

For CB802 = between pin 7 and 8 from chips ICB801S = 16.75Vd
For CM807 =measure across RM807 = 14.74Vdc

For both measures, I moved power board on my table, so test is same as test1.

[Karutcha]

Re: Problem with Samsung LN32C450E1D

For Tom66

For CB802 = between pin 7 and 8 from chips ICB801S = 16.75Vd
For CM807 =measure across RM807 = 14.74Vdc

For both measures, I moved power board on my table, so test is same as test1.

For budm :
I checked your request. In fact I did a new measure and I've got same as before : B13V = 3.78Vdc, B5V = 1.66Vdc, AV = 5.30Vdc, PS_ON = 0.74Vdc

But I'm not able to find cap CM808 !!! do you have an idea where is it ?

[tom66]

Re: Problem with Samsung LN32C450E1D

CM808 is the 630V, 18nF capacitor near transformer, it is not normal electrolytic can cap.

[Karutcha]

Re: Problem with Samsung LN32C450E1D

I found that capacitor, white one, under board I can read CM808. Well, seems to be ok, but I've nothing to measure a capacity.

which kind of measure must I do ?

[tom66]

Re: Problem with Samsung LN32C450E1D

If you don't have a meter to test it, the best thing you can do is just replace it.

[budm]

Re: Problem with Samsung LN32C450E1D

See this thread:
https://www.badcaps.net/forum/showth...38B#post383303

[Karutcha]

Re: Problem with Samsung LN32C450E1D

ok, Is power board needs to be connected to main board to test it properly ?

I mean, if power board is alone, so no connection with main board and driver board, do we have 24Vdc and 13Vdc ?

[budm]

Re: Problem with Samsung LN32C450E1D

Power board by itself, you should have 13v, 24v on the output connector, and 380~390VDC on the main cap since it will be force on by its own pull-up resistor.

[Karutcha]

Re: Problem with Samsung LN32C450E1D

Ok, thanks for your help. I've 3.80 rather 13V and 7.72 rather 24V...So I think your right about CM808 and ICM801. For main cap, Ive 390Vdc.

Well, I go to buy new components, I would give you result later

[budm]

Re: Problem with Samsung LN32C450E1D

It can be just that cap, 0.018uF 630V. Do you have any repair shop close by that more likely to have cap meter to check its capacitance?

[Karutcha]

Re: Problem with Samsung LN32C450E1D

Yes, I will check it tomorrow.