Westinghouse 46" Model VR-4625-Need Help

[budm]

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

Learn about PFC:
https://cdn.badcaps-static.com/pdfs/...13d00f2a03.pdf
https://cdn.badcaps-static.com/pdfs/...e1aa50589e.pdf
https://cdn.badcaps-static.com/pdfs/...f33e6f6571.pdf

[pbones]

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

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?

This statement is incorrect. My testing was done with the power supply in standby mode both times that's why I was seeing the same voltage on the cap. I tested it with the load on and the filter cap is 360 VDC. Sorry for the confusion.

[pbones]

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

more information...when the outputs shut down, the filter cap then measures 166 vdc instead of the 360+ VDC when the outputs are working. I then think the power supply is putting itself into standby mode. The power supply works if I power cycle the supply. What circuit would cause the system to go into standby mode?

[budm]

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

If the PS_ON is present but the PFC Voltage booster drops out then the PFC may have gone into shut down but then it will try to resstart if the PS_ON is present so it will be stuck in the loop, the key is the PS_ON signal. The power supply will go into standby mode if PS_ON is not present, so did the PS_ON drop out?

[pbones]

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

If the PS_ON is present but the PFC Voltage booster drops out then the PFC may have gone into shut down but then it will try to resstart if the PS_ON is present so it will be stuck in the loop, the key is the PS_ON signal. The power supply will go into standby mode if PS_ON is not present, so did the PS_ON drop out?

The ps-on is still active (on) when it drops out.

[budm]

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

So right now then the TV power supply will work for about 10~15 minutes as indicated in post 1 and then the voltage on the main cap will just drop back down to 16~170VDC as if it was commanded to shutdown, right? and when it working, the backlights are also on, right?

[budm]

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

BTW, the part that you think is burnt out (the MOSFET), what voltage do you get on the pins when the PFC is working?
Also the 12V and 24V are present and have correct voltages? We need to find out if the 12V/24V power supply is overload the PFC or not.

[pbones]

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

So right now then the TV power supply will work for about 10~15 minutes as indicated in post 1 and then the voltage on the main cap will just drop back down to 16~170VDC as if it was commanded to shutdown, right? and when it working, the backlights are also on, right?

Correct, and the backlighting works when the outputs are working correctly.

[pbones]

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

BTW, the part that you think is burnt out (the MOSFET), what voltage do you get on the pins when the PFC is working?
Also the 12V and 24V are present and have correct voltages? We need to find out if the 12V/24V power supply is overload the PFC or not.

The one I think is burnt out measures 5volts on the pins. The 12/24v measure 12.07 and 24.1 when its working. The load on each is ~.6 and ~.8 respectively.

[budm]

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

OK, when it works all the voltages are corrected it just shutdown after it is on for awhile. I wonder if you heat up the board first with hair dryer and see if it shutdown faster.

[pbones]

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

OK, when it works all the voltages are corrected it just shutdown after it is on for awhile. I wonder if you heat up the board first with hair dryer and see if it shutdown faster.

Budm, I think your onto something. I used a hair dryer and warmed up the back side of the board (SMD side) plugged the power supply in with all the dummy loads connected and the board shutdown almost immediately, instead of it working for 15+ mintues.

[pbones]

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

Working without a schematic and limit knowledge of the power factor circuit ( PFC). I assume that I will be checking vss reading with the outputs working and then shutdown. I will also be checking the current drawn from pin 7 which is the MOSFET driver pin. I see that pin one can be used as the error array and used to shut the chip down. How would this pin be tested? The if is L6562a st brand.

[pbones]

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

PFC------>>>>>>>>

Outputs are On (working)
GND PIN 6 to PIN 7 (Mosfet driver) 2.5 to 3.0V

GND PIN 6 to PIN 8 (VSS) = 2.5 to 3.0V

PIN 7 amperage draw (measured in series) removed jumper wire to test. Draw is .06 to .08 amps. 60 to 80 mA.

Outputs are off (not working)
GND to Pin 7 =0v
GND to Pin 8 = 0V

[pbones]

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

PFC------>>>>>>>>

Outputs are On (working)
GND PIN 6 to PIN 7 (Mosfet driver) 2.5 to 3.0V

GND PIN 6 to PIN 8 (VSS) = 2.5 to 3.0V

PIN 7 amperage draw (measured in series) removed jumper wire to test. Draw is .06 to .08 amps. 60 to 80 mA.

Outputs are off (not working)
GND to Pin 7 =0v
GND to Pin 8 = 0V

GND Pin 6 to Pin 8 (Vss) = 12.5-13.05 VDC

[budm]

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

"Outputs are off (not working)
GND to Pin 7 =0v
GND to Pin 8 = 0V"

So it lost the VCC voltage to run it, need to trace out as to where it gets the VCC voltage form to run the IC, typical set up the VCC is generated by the AUX winding of the standby power supply that is also used to run the standby power supply SMPS IC, this voltage is fed into a switched transistor that is turned on by the PS_ON signal.

[pbones]

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

"Outputs are off (not working)
GND to Pin 7 =0v
GND to Pin 8 = 0V"

So it lost the VCC voltage to run it, need to trace out as to where it gets the VCC voltage form to run the IC, typical set up the VCC is generated by the AUX winding of the standby power supply that is also used to run the standby power supply SMPS IC, this voltage is fed into a switched transistor that is turned on by the PS_ON signal.

budm, I traced the L6562a back to L6599AD which operates at a self-adjusted voltage between 8-16 vdc. When the outputs drop out this IC vss also drops to zero volts. While the PS_ON is still measuring 5vdc.
Also, there is some browning of the area around ER806F (see pic). The brown area traces lead towards the Mosfet driven by the L6562a. The NTC 2.5d.11 is a thermistor connected which should have 2 ohms when measured and does. This is connected near the browned traces on the board.

[budm]

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

L6599 for the 12V/24V SMPS uses the same voltage generated by the standby power supply AUX winding fed by more likely the same switched transistor for the PFC IC VCC PIN.

[pbones]

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

One more pciture

[pbones]

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

L6599 for the 12V/24V SMPS uses the same voltage generated by the standby power supply AUX winding fed by more likely the same switched transistor for the PFC IC VCC PIN.

budm, I get what your saying but i for the life of me can not see which one it is...can it be seen in my pictures?

[budm]

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

Example of typical setup for the switched transistor for supplying the voltage to PFC and the 12v/24V SMPS.
QB802 is the switched transistor in this example.