7PW22-4 power supply schematic for TV

[sopik78]

Dear friends, anybody can help with schematic or repair guide for TV power supply 7PW22-4?

Thanks in advance

[R_J]

Re: 7PW22-4 power supply schematic for TV

This is all I have, I think it is the same (the 1 might be hidden).

[sopik78]

Re: 7PW22-4 power supply schematic for TV

thank you very much, lets see if I can fix it

[sopik78]

Re: 7PW22-4 power supply schematic for TV

Can somebody help me?

On primary side I measure about 300V instead of 400V as on schematic. On secondary dont have 12V but 7-8V. Where the problem could be?

[budm]

Re: 7PW22-4 power supply schematic for TV

So what exactly it is not doing? There are many Voltages on that board and since that schematic is for many version of PCBA so some of the Voltage reading may not match the print.
How about good clear pictures of the board and the TV MODEL it is used in? You did not provide much information.

[sopik78]

Re: 7PW22-4 power supply schematic for TV

TV Hyundai HLH 26783 DVBT, not working, no power led when turned on.
The power supply had D800 GBU4M damaged, so I changed it. I can read +3,3VSTBY and +5VSTBY, but no other voltages present, when I dont obtain +12 with VCC_12V just 7-8V.

[R_J]

Re: 7PW22-4 power supply schematic for TV

I also found this one, same but with explainations, If you have standby voltages +5VSTBY & +3.3VSTBY Check for power supply on voltage (ST_BY) from main board. This voltage is on PL807 pin #6 1.7 volts in standby and should be 0 volts to turn on the rest of the power supply.

[budm]

Re: 7PW22-4 power supply schematic for TV

Since you do hvae the +3.3STBY on pin10/11 and +5VSTBY on pin 12 for the main board to run then when TV is turned on it should then send out command ST_BY (PS-ON) signal to turn on the rested of the switched power supplies, SO does the ST_BY change state when TV is power on and off? Main board also send out BL_ON/OF and Dim control signals. So at this point we need to know the condition of the control signals and other Voltages on the connectors.
BTW, the schematic is the Master schematic for making the PCB, then the PCB is stuffed to make PCBA for many model of the power supply PCBA's so not all component will be on your board.
BTW, I also see errors in the schematic, I.E. Transformers TR803 has winding pin 9 and pin 10 shorted together, same for PIN 15 and 16, same for TR802 pin 7, 8, 10/11. Not sure what the person that draws the schematic is trying to show.

[sopik78]

Re: 7PW22-4 power supply schematic for TV

So, this is definitelly weird.
When I have PS unplugged from main board, I can read +5VSTBY and +3.3VSTBY and ST_BY about 1.5V. If plugged, +3.3VSTBY stays, +5VSTBY oscillating 3-5V very quick, no ST_BY with not switched on and about 2.3V if switch on.

[budm]

Re: 7PW22-4 power supply schematic for TV

So the ALWAYS ON VCC24V is 24V?
That Vcc_24V is used by buck converter circuits to produce the +5VSTBY and the +3.3VSTBY.
So if the 5VSTBY is not steady with load then you need to start checking the filter caps in that 5VSTBY buck converter section, it can also be that the main board may be loading it down too much.
RJ, thanks for the updated schematic.

[sopik78]

Re: 7PW22-4 power supply schematic for TV

VCC_24V and VCC_12V have 9-10V and 7-8V. This is what I cant understand.

[sopik78]

Re: 7PW22-4 power supply schematic for TV

If I understand right, when plugged in AC, I should find these outputs on DC side on power supply itself (with no mainboard connected): VCC_24V, VCC_12V, +3.3VSTBY, +5VSTBY, ST_BY?
Or what is the power sequence?
I still don't undestand why is VCC_24V and VCC_12V so low.

[R_J]

Re: 7PW22-4 power supply schematic for TV

When the power supply is in standby, IC827 is in Burst mode, (standby) It supplies a partial VCC_24v to PL801 which supplies the +3.3STBY and the +5STBY
the VCC_24v at this time can only supply enough current for the standby circuits.
When the ST_BY pin is taken low (0v) It places IC827 into full mode which can then supply enough current for the 24 volts etc.
You should have close to 12 volts VCC_12V if you do not, C837 and C836 could be bad.