AKAI AKFL3254HF1 dead

[rtstorm]

Hello, i have this AKAI LCD TV that was burned. I found that mosfet was open and it burned. The bridge rectifier was shorted in AC, shorted 3 x1 Ohm resistor and 4 x 20 Ohm SMD resistor. I replace them and TV show red light (like stand by light) but it wont respond to POWER button.

After some minutes i noticed smell, i check it and found that 3 x 1 Ohm was burned (shorted, 0 Ohm).

I must say that i put different bridge rectifier instead RS405M i use KBU 810, but i do n ot think this will make problem.

[rtstorm]

Re: AKAI AKFL3254HF1 dead

Does anyone have schematic of this?

[rtstorm]

Re: AKAI AKFL3254HF1 dead

i find that i have 5V standby and i think main board wont turn on main 12V/24V

Any ideas?

[newtothis]

Re: AKAI AKFL3254HF1 dead

What voltage are you getting at the PS_ON pin when attempting to power the set?

[ammarben]

Re: AKAI AKFL3254HF1 dead

start power supply alone ps-on to 5v with 1k resistor

[rtstorm]

Re: AKAI AKFL3254HF1 dead

Is this bad steper coil of what ever it is called?

[rtstorm]

Re: AKAI AKFL3254HF1 dead

What voltage are you getting at the PS_ON pin when attempting to power the set?

i have 4.28V all the time, and when i press POWER it stay at 4.28V

[newtothis]

Re: AKAI AKFL3254HF1 dead

Is this bad steper coil of what ever it is called?

Is that the board in its current state?

[rtstorm]

Re: AKAI AKFL3254HF1 dead

no, i replace resistor that was burned.

[newtothis]

Re: AKAI AKFL3254HF1 dead

Just a resistor??

There are multiple missing components and components that have not been soldered in.

There is also a pad torn up

If that is that state of the board how do you expect it to work?

[budm]

Re: AKAI AKFL3254HF1 dead

Those resistors are connected in parallel so the resistance will be very low, so did you check those 3 large resistors off the board, they usually go open circuit when too much current flow through them, they are for the Source resistor for the power MOSFET for the PFC Voltage booster circuit. Did you check to see if the MOSFET has Source to Drain shorted out. Without working PFC Voltage booster circuit, you will not have 12V/24V due to the circuit needs the boosted Voltage to operate. More likely the PFC IC controller is also damaged.

[rtstorm]

Re: AKAI AKFL3254HF1 dead

Just a resistor??

There are multiple missing components and components that have not been soldered in.

There is also a pad torn up

If that is that state of the board how do you expect it to work?

no i just use the old picture, this in new one

[rtstorm]

Re: AKAI AKFL3254HF1 dead

Those resistors are connected in parallel so the resistance will be very low, so did you check those 3 large resistors off the board, they usually go open circuit when too much current flow through them, they are for the Source resistor for the power MOSFET for the PFC Voltage booster circuit. Did you check to see if the MOSFET has Source to Drain shorted out. Without working PFC Voltage booster circuit, you will not have 12V/24V due to the circuit needs the boosted Voltage to operate. More likely the PFC IC controller is also damaged.

In first when i got the TV those 3 resistor wehe dead, MOSFET dead (shorted), i repalce 3 resistor with new one (1 ohm) and new MOSFET MDF13N50.

Now i take these new resistor away from board and they still show 1ohm resist but look on the photo what happen to them.

Can you point me to PFC IC on the board? how to check it?

[budm]

Re: AKAI AKFL3254HF1 dead

When that PFC MOSFET is shorted out, it should have blown the main fuse.
No need to check the PFC IC (bottom right 8-PIN SMD IC closed to the main fuse), just replace it, and also need to check the Gate drive resistor/diode/transistor.

[rtstorm]

Re: AKAI AKFL3254HF1 dead

hello, i replace PFC IC. When i put power to TV it change for red (stand by) to blue but then my dimm test bulb start glow and then u pull the plug. Is this normally when TV start?

[rtstorm]

Re: AKAI AKFL3254HF1 dead

i try to disconnect invertor and i still have bulb light after i turn on TV. Please any suggestion?

[rtstorm]

Re: AKAI AKFL3254HF1 dead

is it safe tu keep runing tv when bulb test glow? Please help

[ammarben]

Re: AKAI AKFL3254HF1 dead

is it safe tu keep runing tv when bulb test glow?
NO you have short circuit