LG42pa4500, YSUS problem

Measure the resistances to ground on highlighted 7 pins (picture below).

Measure made without 2xKF7N60, diode
1-3 OL
4- 4.5k
5-7 OL

Replace the damaged components again and try to turn on the TV with disconnected FFC cable (picture below):

I dont have more KF7N60 atm. Could I use P4NK60Z? It have better ns, only worst diffrent is that they are 4A, not 7A. It will be good just for test?

Arni ha scritto:I dont have more KF7N60 atm. Could I use P4NK60Z? It have better ns, only worst diffrent is that they are 4A, not 7A. It will be good just for test?

I think the transistors P4NK60Z should be okay for this test.

Ok done, It NOT blow now.
But I noticed somthing weird. This line (Vs) not get 205V, when FFC cable is disconnected.

Arni ha scritto:This line (Vs) not get 205V, when FFC cable is disconnected.

Check, if the "Vs" voltage appear for a short time, when you turn on the TV.

matic ha scritto:Check, if the "Vs" voltage appear for a short time, when you turn on the TV.

Yep but It was weird. Only in few sec peak. Peak was only 2V

Connect a 230V bulb to the "Vs" power rail and check, if the bulb lights up for a short time, when you turn on the TV. I use a 15W/230V bulb from the fridge.

Yep it was shining
I was so supprised
Nothing exploded
It was shining long time, not just moment.

I made some more Measure. I check that small board (Responsible for FFC cable), everything looks fine.
What's more when bulb lights up, this is how looks Voltage.

This mean the bulb was consuming all power? right?

Arni ha scritto:I dont have more KF7N60 atm. Could I use P4NK60Z? It have better ns, only worst diffrent is that they are 4A, not 7A. It will be good just for test?

Przepraszam, że tak długo nie wracałem do tematu, ale czekałem na dostawę z aliexpress.
Na chwile obecną mam ich dużo z aliexpress. Zmieniłem te P4NK60Z na oryginalny KF7N60. Nic nie wybuchło, gdy włączyłem telewizor z odłączonym kablem FFC. Na linii było 205 V (Vs).
Postanowiłem normalnie włączyć telewizor. Wszystko uruchomiło się normalnie. (Myślę, że problem był w 4mosfetach: 2xKF7N60,2XRJP30H2A). Następnym razem, gdy będę wymieniać, wymienię je wszystkie, nawet jeśli tylko jeden lub dwa będą wyglądać na uszkodzone.


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Sorry I didn't write for so long, but I was waiting for delivery from aliexpress.
Now I have a lot of them from aliexpress. I changed this P4NK60Z for orginal KF7N60. Nothing blow up when I turn on the TV with disconnected FFC cable. There was 205V on line (Vs).
I decided to turn on the tv normally. Everything started normally. (I think problem was in 4mosfets, 2xKF7N60,2XRJP30H2A). Next time I will repleace all of them even only one or two will be damaged.


Thanks much matic