LG 32LN5400 what is this resistor value?

[Biruslapio]

TV was on and the owner heard a pop, the power supply 331J 1kV cap blew up and damaged the main mosfet, resistor, main fuse and the PFC controller.

The MOSFET was an 11A 650V MOSFET, I put an 11A 600V which is the closest I have, the resistor color code was not standard, I replaced with another one from another LG PSU PFC section, it's less than 1 OHM, seems to be called rOCP.

Now it powers up and LEDs + Mainboard works fine but with a hellish noise like coil whine, it is coming from the primary, from the transformer or the inductor, it's not bad soldering, the thing is, when powered up the voltage on main caps are 262~280V, strangely the tv works like that, this TV should have PFC, it's not boosting, the only thing different now is the rOCP and the MOSFET.

I circled the components that were exchanged in the photos. The photo of the lone resistor is the original rCOP that went open.

[lotas]

Re: LG 32LN5400 what is this resistor value?

Power schematic LGP32-13PL1

[petehall347]

Re: LG 32LN5400 what is this resistor value?

i once had a tv supply wining and also it was drawing high current from the mains .turned out to be bad soldering on the replaced pfc ic . tv also worked

[lotas]

Re: LG 32LN5400 what is this resistor value?

This circuit is without PFC.

[R_J]

Re: LG 32LN5400 what is this resistor value?

You need to install a proper 0.25Ω resistor, 1Ω is too large and will upset the ocp of ic101

[lotas]

Re: LG 32LN5400 what is this resistor value?

From the photo it is already 0.05 Ohm, +/- 5%

[Biruslapio]

Re: LG 32LN5400 what is this resistor value?

Very useful, thank you so much!
The last black band is what caused this, it has no purpose in the resitance value or tolerance.

I've fixed it, it was the resistor R113, supposed to be 0.25Ω, the one I wrongly replaced was 0.05 Ω, the PFC could've blown up from the overcurrent, I did a parallel association between an 0.3 and 2.2Ω, ended up with around 0.26, that was good enough, TV is fine.

List of parts replaced:

Q101 MDF11N65B
C102 330pF 1kV
R113 0.25Ω
R106 220Ω
F100 5A
IC101 Sanken SSC1S311A

I learned it's not PFC, that was a gereneric way of calling the "Multi SMPS" circuit with a mosfet.

[R_J]

Re: LG 32LN5400 what is this resistor value?

The black band on the end usually means non-inductive.
With the wrong value resistor, the ic would be operating in the wrong mode, this would result in the noise from the transformer.

[angelos]

Re: LG 32LN5400 what is this resistor value?

Hi Biruslapio,
I had the 32LN5130 model blown and i had to replace all the same parts that you did.
The challenge was for me to find a 0.25 Ohm resistor so I combined two of them until my ESR meter gave me 0.26 Ohm, the i was satisfied.
The striking similarity was that we changed all the same parts. I changed the PC817 opto coupler just in case.

Lotas, Thank you for the diagram of the power supply it will really come in handy. Tell me how do you get the power supply diagram when the service manual does not how it. Do you have more circuit diagrams of LG?

[Steve2023]

Re: LG 32LN5400 what is this resistor value?

Hi, old thread bump but what type of resistor is this?

Is it a wirewound resistor or metal film resistor?

Does it matter if a metal film resistor is used?

Also is it a 2W resistor?

Thanks :-)


Edit ok going by that schematic file it's a wirewound resistor :-)

[Biruslapio]

Re: LG 32LN5400 what is this resistor value?

it was a 2W resistor, standard type? don't know the material.

[Steve2023]

Re: LG 32LN5400 what is this resistor value?

it was a 2W resistor, standard type? don't know the material.

Been told it should be a fusible resistor

[R_J]

Re: LG 32LN5400 what is this resistor value?

it was a 2W resistor, standard type? don't know the material.

If you use a wire wound it should be a NON-Inductive type as well

[alfatv]

Re: LG 32LN5400 what is this resistor value?

If you use a wire wound it should be a NON-Inductive type as well

There is always some inductance.