Philips 42PFP5532D/12 power supply overvoltage

[kmx200]

Dear friends

I own a Philips 42PFP5532D/12 plasma tv which stopped working a few months ago.
When I try to power on the tv set, I hear a clicking sound inside and the front led starts blinking.
So, I opened the case and the first thing I checked is the power supply (the known to many of us, Samsung PS-507-PHN).
At first, I checked for blown fuses and shorted diodes with my DMM, and for shorted coils with the Blue Ring ping tester. All of them looked ok (I unsoldered them prior to testing).
Then, I found many blown output capacitors and replaced ALL of them with the exact same values.
After replacing the bad caps, I tried to turn on the PSU by bridging the D5V and VS_ON pins but after a few seconds, it shut off and the small fault board started blinking twice, which means VA error.
So after that, I found out that the VA voltage starts rising till ~200VDC (it should be 61-65VDC) and then it shuts off.
Then I checked the optocouplers, zener diodes and resistors but everything was ok.
I also replaced the PWM IC and the shunt regulator with new ones.
The problem persists, and the only thing I can guess is a bad smd cap which has to do with the PWM IC oscillator.
Any ideas dear friends?
I have spent many hours looking for the problem because I want to get better on troubleshooting SMPS's.
Thank you in advance for your time and I apologize if I tired you!

[ReeceyBurger123]

Re: Philips 42PFP5532D/12 power supply overvoltage

You got Va confused with Vs ? Va wont ever go that high its driven by a different fet than Vs which runs at 200v !

[kmx200]

Re: Philips 42PFP5532D/12 power supply overvoltage

Thank you very much for your quick reply. One of my thoughts was that the VA got confused with the VS because VA should be 65VDC max!
I believe that there is a problem with the RC circuit of the the PWM IC, so there is a higher frequency of oscillation! You can also see the proper voltages in one of the above photos. I forgot to mention that I use the cold ground to measure the output voltages.

[Andrew F. Ali]

Re: Philips 42PFP5532D/12 power supply overvoltage

Nothing wrong with the PSU. I think your problem is either the Y-sus or Z-sus Bd. Most time s it's the Y-sus Bd that faulters.

[rickou]

Re: Philips 42PFP5532D/12 power supply overvoltage

What color is the front led when it blinks?
Blinks fast or slow or both?

[rickou]

Re: Philips 42PFP5532D/12 power supply overvoltage

Have you check the cap DC8203 and DC830? Can you see if the IC U8003 (KIA7815A) work if is hot and don't work if is cold.