Westinghouse 46" Model VR-4625-Need Help

[pbones]

I have a westinghouse 46" TV model VR-4625. The power supply is giving me problems. I have replaced all the caps, tested the Mosfets, tested the diodes tested the recitifer tested the filter cap, ...etc. All is good. But the supply shuts the outputs down, not all only the 12v and 24v get shutdown after 15 mintues of use. I have tested the supply alone with dummy loads above the min. specs and still the supply shuts down.

I need some information about an IC. I have a Haider HDAD240W402 power supply. The IC marked M401 (near the outputs, low side) looks chared and I am unable to read or see any information on the chip. If you have this power supply can you please post the IC markings.

Thanks

[budm]

Re: Westinghouse 46" Model VR-4625-Need Help

How about giving us more info:
https://www.badcaps.net/forum/showthread.php?t=39740

[pbones]

Re: Westinghouse 46" Model VR-4625-Need Help

Here is a picture of the chip i need identified, and the top of the supply.

[pbones]

Re: Westinghouse 46" Model VR-4625-Need Help

Maybe these are clearer...

[budm]

Re: Westinghouse 46" Model VR-4625-Need Help

That looks to be a Power MOSFET for switched 5V, you can see 4 of the legs in one side all tied together, another 3 on the other side are tied together and connected to the + output of the pi fiter inductor, the single pin (pin4 ??) is the GATE pin.
http://www.shopjimmy.com/westinghous...version-1.htm#

[pbones]

Re: Westinghouse 46" Model VR-4625-Need Help

Thanks if that's the 5v MOSFETi assume that it won't be the reasonthe 12/24v puputs are shutting down. Do you know how I can test or trace the problem with the two outputs that are shutting down?

[budm]

Re: Westinghouse 46" Model VR-4625-Need Help

Pictures of the whole backs of the TV so we can see what we are dealing with?

[pbones]

Re: Westinghouse 46" Model VR-4625-Need Help

Pictures of the whole backs of the TV so we can see what we are dealing with?

Budm, I have the power supply operating indepent of the tv. Can you specify which external board your interested in viewing? Thanks

[pbones]

Re: Westinghouse 46" Model VR-4625-Need Help

Since I have been working on this problem for weeks. I will post a link to my thread in a seperate forum. This will provide details and some background of my problem.
http://forum.allaboutcircuits.com/sh...d.php?t=100594

[budm]

Re: Westinghouse 46" Model VR-4625-Need Help

So force on the power supply on the PS_ON pin using resistor between STBY Voltage and the PS_ON pin? When it goes off, is the PFC Voltage booster circuit still function? What dc Voltage do you have on the main filter cap when the 12/24V is working and when it stops working? That bad switched MOSFET is used for feeding what circuit I do not know, can't tell where that connection goes to, there may be shorted circuit that took out that MOSFET, you need to check and see what voltage you have on both side of the MOSFET pins.
So what resistor did you put in and where is this resistor at on the board?

I am also confused now about your problem:
"Prior to the last change I had 12V, 5v and 24 Volts now the 12 volts is 8v, 24v is 17, 5v is 5v 5V sense is zero."

And now the 12V and 24 will shutdow, but were they still putting out 12V and d24V or they were still putting out 8V and 17V?
I cannot download your pictures zip files since I need to register.

[pbones]

Re: Westinghouse 46" Model VR-4625-Need Help

So force on the power supply on the PS_ON pin using resistor between STBY Voltage and the PS_ON pin? When it goes off, is the PFC Voltage booster circuit still function? What dc Voltage do you have on the main filter cap when the 12/24V is working and when it stops working? That bad switched MOSFET is used for feeding what circuit I do not know, can't tell where that connection goes to, there may be shorted circuit that took out that MOSFET, you need to check and see what voltage you have on both side of the MOSFET pins.

I have the power supply forced on, when the outputs go down there is 166 vdc on the filter cap. The same as when the outputs are functioning. I assume your asking me to locate the pfc ic and test the V+ to GND pin on the ic?

[budm]

Re: Westinghouse 46" Model VR-4625-Need Help

BTW, those two resistor connected in parallel that you replaced with 15 something Ohms resistors, they are 0.15 Ohms resistors use for the Source pin of the power MOSFET used for the PFC Voltage booster circuit. 12V/24V SMPS section needs correct voltage from PFC to run properly, around 360~400VDC depends on the requirement of the 12V/24V SMPS.

[budm]

Re: Westinghouse 46" Model VR-4625-Need Help

When you force on, the voltage RIGHT at the two legs of the cap should be around 360~400VDC and stays there as long as the PS_ON is present.

[budm]

Re: Westinghouse 46" Model VR-4625-Need Help

IC301 is the PFC Controller. Did you put the 0.15 Ohms resistors back in place?

[pbones]

Re: Westinghouse 46" Model VR-4625-Need Help

BTW, those two resistor connected in parallel that you replaced with 15 something Ohms resistors, they are 0.15 Ohms resistors use for the Source pin of the power MOSFET used for the PFC Voltage booster circuit. 12V/24V SMPS section needs correct voltage from PFC to run properly, around 360~400VDC depends on the requirement of the 12V/24V SMPS.

Thank you. I realized the error in reading the six band resistor and placed the .15 ohm resistors back into the circuit. The 15.8's were removed. There should be 360-400 vdc on the source of the power mosfet feeding the pfc ckt? Is the value measured to chassis gnd or filter cap (-)?

[budm]

Re: Westinghouse 46" Model VR-4625-Need Help

The 360~400VDC is generated by the PFC Voltage booster circuit, you are working in the primary hot deadly side of the circuit so chassis ground is NOT the ground ref point for the primary circuit.
The negative leg of the main filter cap is the ground ref point for DC voltage measurement in the primary side.
So measure right at the two legs of the main filter cap.

[pbones]

Re: Westinghouse 46" Model VR-4625-Need Help

When you force on, the voltage RIGHT at the two legs of the cap should be around 360~400VDC and stays there as long as the PS_ON is present.

If that's the values the filter cap leads should measure then I am not getting the correct voltage to the filter cap. For that matter I am not getting that voltage on the dc side of the bridge rectifer either. The bridge is around 170 vbc. With 120 vac on the input.

[budm]

Re: Westinghouse 46" Model VR-4625-Need Help

When TV is plugged in but not turn on, the power supply will be in standby mode, the voltage on the main filter cap will be around 170VDC, when PS_ON is applied then the voltage on the filter cap should jump up to around 360~400VDC, if not, then the PFC Voltage booster is not working.

[pbones]

Re: Westinghouse 46" Model VR-4625-Need Help

The 360~400VDC is generated by the PFC Voltage booster circuit, you are working in the primary hot deadly side of the circuit so chassis ground is NOT the ground ref point for the primary circuit.
The negative leg of the main filter cap is the ground ref point for DC voltage measurement in the primary side.
So measure right at the two legs of the main filter cap.

Hmm... then I am focusing on the wrong side. Thanks for the help too. I deal and take measurements on un-grounded conductors most days.
Is the bridge upstream or down stream of the pfc ?

[budm]

Re: Westinghouse 46" Model VR-4625-Need Help

Upstream, just find out what you have on the main filter cap, you have to have PFC Voltage booster, no need to go further util you get the PFC working first.
SJ has the board for $45, so if it needs lots of parts, then you may be better off with new board.