sanyo no back ligth

[ealequi]

Re: sanyo no back ligth

do i need the board pug tocheck the diode?

[MisterD]

Re: sanyo no back ligth

Okay, Did you hook the negative probe of your volt meter to the negative lead of the Capacitor C821 on the power supply board? it must be hooked here for the ground connection otherwise it will not give you any voltages, and please leave it there for checking these voltages bud has asked for? these are DC Voltages not resistance. Then you will remove the negative probe from C821 and make sure the power is off then check resistance of the other components as you normally would.

[budm]

Re: sanyo no back ligth

"This is very strange. none of the one you ask me to test has power pin 16 on ic301, zd601,q303, r320,q602. i check the meter in other resistant and it is working." I do not understand this statement. I want resistance reading, especially the Zener diode and the transistors to make sure they are not shorted out first, if they are bad , then the voltage reading will be next. Step by step.
And the parts are on the bottom side of the board plus they are also on the hot (deadly side of the circuits, must be real careful) you will have to have the board power up with the lamps connected just in case the inverter circuits kick on, you do want high voltage arcing.
"it is working" what is working?

[ealequi]

Re: sanyo no back ligth

One more thing, I want to apology to every one that is helping me, but been cristmas time you get unexpected visitor and has to stop doing what i really want to be respecfull. Again my apology.

[ealequi]

Re: sanyo no back ligth

This is very strange. none of the one you ask me to test has power pin 16 on ic301, zd601,q303, r320,q602. i check the meter in other resistant and it is working.

[ealequi]

Re: sanyo no back ligth

hey i am here. i am testing it. for me it take forever, want to make sure i dont mess something else. i will give you the result withing minute.

[budm]

Re: sanyo no back ligth

Some time I felt like wasting so much time tracing out so many boards for the forum (not many people are willing to do) from bad pictures, and no follow-up.

[tom66]

Re: sanyo no back ligth

I do hate when people disappear mid-thread as we are getting ever closer...

[budm]

Re: sanyo no back ligth

So are you still working on this? Lots of time spending on tracing out the board.

[budm]

Re: sanyo no back ligth

OK, the last set of pictures, some are really good, some are kind of dark and yellowish/greenish pictures.
But I am able to trace out how the PWM IC for the backlights inverter gets its power from.
It is generated by the AUX winding of the 12v power supply. the output is fed through first voltage regulator circuits (Q602, Zener Diode ZD601), the output of the regulator then is fed to the switched transistor Q303 which is turn on by the OPTO IC 303 when the BL_ON (BL-SW) is applied.
So we need to find out if we are getting the VCC on pin 16 of the PWM IC301.
We still need the P/N of those IC's.
You will need to find the way to measure the voltages.
Make sure to use the negative leg of C821 as your GROUND REF.
Check ZD601, Q602, Q303, R320.

[ealequi]

Re: sanyo no back ligth

sorry i was not home

[ealequi]

Re: sanyo no back ligth

[budm]

Re: sanyo no back ligth

OK, what are the P/N for these two IC?
Per diagram and look at the bottom of your board, check C312.

[budm]

Re: sanyo no back ligth

I trace out the board, R322 is the main fusible resistor that feeds other fusible resistor for the 5V SMPS, and also the 12v SMPS circuits, so it must be OK.

[selldoor]

Re: sanyo no back ligth

I wasnt sure about the soldering on that resistor - How about a voltage reading at both ends ?

[tom66]

Re: sanyo no back ligth

R322 was tested at 3 ohms. Given the lead resistance from a typical DMM, that seems like a good fusible resistor.

[budm]

Re: sanyo no back ligth

see post 140

[budm]

Re: sanyo no back ligth

Please take more pictures.

[ealequi]

Re: sanyo no back ligth

can you give me the location pls.?

[budm]

Re: sanyo no back ligth

So is R322 good or bad? I did not see the reply.
By the way the BL_ON at 1.7V is OK, I look at the circuit, it is fed by the 3.3V power supply for the switched transistor Q1805 of the main board. So you can splice the BL_ON wire back together and make sure to remove the 1K resistor from CN6.
The power supply board uses PFC Voltage booster, so he needs to check the voltage on th capacitor C821, it should have 170VDC when TV is off and about 380~390VDC when V is ON.