when i turn on, Philliips TV is not on

[Nish]

Re: when i turn on, Philliips TV is not on

I put 1k resistor to connect P-ON-H1 to AL+5V.

Now reading

C912 = 13.40
C906 = 18.96
C951A = 5.56

Across ZD907 = 1.30

No voltage at output of IC902

[R_J]

Re: when i turn on, Philliips TV is not on

When you add the 1k to turn on the power supply, does the voltage on ic902, pin1 change? this is the ENable pin for the regulator, If it is changing (logic high) and you still have no output from ic902, either the ic is bad or there is a short on the output. If the ouput voltage is 0 volts I would suspect the ic, if there is 1~2 volts, It could be too high a load. as ic801 and ic601 have 10Ω resistors in there VCC lines.

[Nish]

Re: when i turn on, Philliips TV is not on

Before install 1k resistor
PC902
Pin4 = 16.22
Pin3 = 15.55
C906 = 16.20

After 1k resistor install
PC902
Pin4 = 19
Pin3 = 18.55
C906 = 19

Output voltage of IC902 = 0.053v and goes to 0v right away.

[R_J]

Re: when i turn on, Philliips TV is not on

Looks like the regulator is bad, It should output around 15~17v when ENable is high.

[Nish]

Re: when i turn on, Philliips TV is not on

I try to buy the regulator. I couldn't find this ic. I have attached the picture.

[R_J]

Re: when i turn on, Philliips TV is not on

You can order them from China. They seem to be a custom part number but are likely made by Texas Instruments, and might be a TPS7A4501DCQR or TL1963ADCQR I have not tried any of these substitutes.

[Nish]

Re: when i turn on, Philliips TV is not on

IC902

Pin4 = 16.42
Pin5 = 1.27


IC601 PIN12= 16.24

[R_J]

Re: when i turn on, Philliips TV is not on

IC601 provides about 17v internally. This is a low current voltage and needs to be suplemented by IC902 for the ic to work.
IC902 supplies the VCC voltage for IC801, pin12 and IC601, pin12 and also turns on Q802, which turns on Q800, which tells both IC801 and IC601 to start.

I suspect if you replace the regulator ic, the power supply could be close to being fixed.

[Nish]

Re: when i turn on, Philliips TV is not on

IC801 pin12 = 16.18v
IC601 pin12 = 16.24v
Q802 =0.659v
Q800 = 0v

I will replace R818 and see

[R_J]

Re: when i turn on, Philliips TV is not on

What is the point of replacing R818? Why do you think they have the regulator ic in this circuit?

[Nish]

Re: when i turn on, Philliips TV is not on

When I measure resistance, I did not get resistance. I thought bad resistor.

[Nish]

Re: when i turn on, Philliips TV is not on

What should I do?

[R_J]

Re: when i turn on, Philliips TV is not on

What should I do?

Replace the regulator ic! The chances of that 10K resistor being bad is next to imposible.

Again: Why do you think they have the regulator ic902 in this circuit?

[Nish]

Re: when i turn on, Philliips TV is not on

Replace the regulator ic! The chances of that 10K resistor being bad is next to imposible.

Again: Why do you think they have the regulator ic902 in this circuit?

To supply voltage to IC801 and IC601. That's what I think.

[R_J]

Re: when i turn on, Philliips TV is not on

To supply voltage to IC801 and IC601. That's what I think.

That is correct. So if the INPUT has (19v) and the enable pin is high (18.5v) and the OUTPUT is 0 volts, (and the output line is not shorted to ground) what could be wrong.

[Nish]

Re: when i turn on, Philliips TV is not on

That is correct. So if the INPUT has (19v) and the enable pin is high (18.5v) and the OUTPUT is 0 volts, (and the output line is not shorted to ground) what could be wrong.

Should be the regulator IC902 is not functioning.


But the IC902 pins are reading the below voltage.

IC902
Pin1 = 2.527v
Pin2 = 19.19v
Pin3 = 0v (gnd)
Pin4 = 16.24v (output)
Pin5 = 1.29v
Pin6 = 0v (gnd)

Is this IC not working? I am confuse.

[R_J]

Re: when i turn on, Philliips TV is not on

Should be the regulator IC902 is not functioning.


But the IC902 pins are reading the below voltage.

IC902
Pin1 = 2.527v
Pin2 = 19.19v
Pin3 = 0v (gnd)
Pin4 = 16.24v (output)
Pin5 = 1.29v
Pin6 = 0v (gnd)

Is this IC not working? I am confuse.

I was going by what you reported earlier in post# 143

Output voltage of IC902 = 0.053v and goes to 0v right away.

and post#141

No voltage at output of IC902

That is why I suspected the regulator, so it IS working ok.

So you should now have PANEL+24V and P-ON+12V

[Nish]

Re: when i turn on, Philliips TV is not on

I was going by what you reported earlier in post# 143 and post#141 That is why I suspected the regulator, so it IS working ok.

So you should now have PANEL+24V and P-ON+12V

Ok sorry about that. I mislead you.


No I do not have PANEL+24V and P-ON+12V at the connector.

I have attached the picture of voltage now.

[Nish]

Re: when i turn on, Philliips TV is not on

Is there anything I can check please?

[R_J]

Re: when i turn on, Philliips TV is not on

The only voltage that points to a line is the 350v, That tells be that the pfc circuit and IC801 is working. The 16.24 seems to be the vcc supply, so that is correct. Is the 1.1 volts for pin 4 or pin5 of IC601?
I have no idea where you measured the 87.2
Looks like the IC601 circuit is not working, check the resistance of R618(15Ω), R617(51Ω) and R620(51Ω) and [R52 1](15Ω) If they are ok. Check the voltage on pins 11,14 & 15, Also is there any voltage on D601 cathode?

I looked closer at the connections on T601, The connections on pins 1 & 2 don't look that good, Remove the old solder, clean up the trace and rivet and resolder them