Thank you for the schematics and sugegstions.
This is how the two connectors signnal pins look on the PSU board.
AP3041 ic seems to need at least 3.3v on the PWM pin. It is unclear if PWM pin has pull up inside the AP3041 - I will measure the voltage on this pin and try to apply some 3.3-5.0 DC DC voltage on it via some series resistor.
Will experiment more once i install back the LED drive board module on the PSU board. Plan to supply 12V to that LED driver module board and measure few voltages ->iW7027 has a 5Vcc exit on pin 2 (5VDD).



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Thank you. Checking closer the backlight drive I found this PSU RSAG7.820.8364 board uses IW7027 QFP IC as pure LED driver and AP3041 IC as voltage boost controller for LED driver.
Backlight voltage sits at around 30V in standby then goes to 40V when PSU board STB and BSW pins activated with 3.3v but voltage but never goes close to 60V. It is possible this AP3041 may not work to boost the voltage used for LEDs and its "flag" pin signal may disable the LED driver too.
The only schematic with AP3041 is in IC datasheet could not find any Hisense PSU schematic with it.

I am trying to repair a 50 inch Hisense RG50 model TV that has solid red light when connected to power point and no change when attempting to power on the TV from hardware button.
Backlight does not come on and no image on LCD screen when checking with a flashlight.

This RG50 tv has next boards in it:
- PSU board number: RSAG7.820.8364.
Found no close schematoic for it. After cleaning the annoying Conformal Coating from the ICs I found it uses IDP2303 for PFC and the 3 voltages 12V, 16V and some 40V used for backlight (40V supposed to be 60V).
Also uses IW7027...

I have in Hisense RG50 -> PSU board number: RSAG7.820.8364 where no close schamatic available. It uses IDP2303 IC for PFC I think and Dialog IW7027 for backlight driver.

This might be its schematic.
Investigating if I can install BGA DDR4 chips to get 16GB memory instead of 8GB currently on it....

Thank you for the very good suggestions. Did not know about the Panasonic design guide. This is the first VRM I repaired (I usually repair 230V SMPS) and was not sure about the small ringing on the waveform.
"Quite warm" is indeed not the best description to use will remeber this.I have not measured with a thermometer but I estimated 45 degrees.
You are correct about the efficiency of the older VRMs, nothing seems to be wrong anymore with that VRM. The heat generated by CPU seems to slowly move through the PCB copper layers into the VRM caps and coils that are nearby....

I used these Panasonic FK seriers caps for recapping the VRM Vcore line. Hope they are the right type for the VRM needs.
https://uk.farnell.com/panasonic/eeu...-20/dp/1744873

Plan to replace the remaining two phases high side Mosfets with the higher spec STD86N3LH5 and check if any improvement.

This board had the initial fault in VRM with high side Mosfet from PWM1 (phase 1) getting very hot. It also had the VRM caps quicly heating up in 10-15 seconds after power on.

This board uses mext ICs and Mosfets in VRM:
- ADP3180 PWM controller - in 3 phase mode
- ADP3418 as Modfet drivers
- High side Mosfets STD38NH02L (from ST)
- Low side Mosfets STD90NH02L

Some of the symptoms were very similar with the "Dead Asus P5P800-VM" in this forum.
I had the sawtooth voltage on Vcore too this was probably the cause of the Vcore caps...