when i turn on, Philliips TV is not on

[Nish]

Hi all, my TV is Phillips 55PFL5505D/F7. when i powered up nothing happened. standby light not on. I opened the cover and try to measure voltage. I do not have 5Vdc, 3.3v at the connector 2.

IC902 (I replaced new one still same voltage)
pin1 --> 0.025v
pin2 --> 0.485v
pin3 --> 0v
pin4 --> 0v
pin5 --> 0v

IC901 (I replaced new one still same voltage)
pin1 --> 0v to 1.2v (changing, not stable)
pin2 --> 4.96v
pin3 --> 0v
pin4 --> 169.7v
pin5 -->169.7v
pin6 -->0v
pin7 -->10v to 16v (changing, not stable,) {when i remove the C912, it become stable 13V, i replace new cap and still changing)
pin8 -->0v

T901
pin1 --> 0.009v
pin2 --> 0.010v
pin3 --> 0.015v
pin4 --> 0.006v
pin5 --> 0v
pin6 --> 0v
pin7 --> 0v
pin9 --> 169.4v
pin10 --> 169.7v


Can anyone help me please?

[neilc6]

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

I would check for shorted diodes and transistors on the power supply. Need the pin labels and voltages on the power supply connector. There should be troubleshooting flowchart in service manual.

[Nish]

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

CN5
pin1 --> 0V pin6 --> 0V
pin2 --> 0V pin7 --> 0V
pin3 --> 0V pin8 --> 0V
pin4 --> 0V pin9 --> 0V
pin5 --> 0V pin10 --> 0V

CN5
pin1 --> 0V pin8 --> 0V
pin2 --> 0V pin9 --> 0V
pin3 --> 0V pin10 --> 0V
pin4 --> 0V pin11 --> 0V
pin5 --> 0V pin12 --> 0V
pin6 --> 0V pin13 --> 0V
pin7 --> 0V pin14 --> 0V


CN2
pin1 --> 0V pin8 --> 0V
pin2 --> 0V pin9 --> 0V
pin3 --> 0V pin10 --> 0V
pin4 --> 0V pin11 --> -0.139V
pin5 --> 0V pin12 --> 0V
pin6 --> 0V pin13 --> 0V
pin7 --> 0V pin14 --> 0V

[R_J]

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

On ic901, pin 7 (vcc) is changing because the ic is trying to start but is being shut down. It will only rise to 17 volts due to the zener diode ZD904.
Do you get any voltage at all on C951a ? If it is 0 volts, check the diodes D950~952 and also ZD951, it could be shorted killing the 5 volts.
I see there is also 3.1 volts on D903/C906, this also indicates the secondary's are trying to produce some voltage.
so you should see some voltage on C951a
If the original ic was bad, check the two resistors R909,R910 off pin3,

[digitalpc]

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

do u check optocoupler?

in some motherboard i use dc power supply 30v 5amp in big caps and see if is taking any power(something getting hot) or not

[Nish]

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

C951a = 0.170v ( negative probe in negative of cap)
Those diode looks Ok, I will remove those diode.

[Nish]

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

I removed those 3 diode, measured in diode mode it reads 0.239v.

[Nish]

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

Opps I blow out the chip IC901. I need to order parts to replace. I think I short.

[Nish]

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

C951a = 0.170v ( negative probe in negative of cap)
Those diode looks Ok, I will remove those diode.

[Nish]

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

Thank you neilc6, R_J and digitalpc for helping me to solve my problem.

I have replaced D951, D950, ZD951 and the the IC901 since I blown up.

As per digitalpc I applied and I found C952 gets hot. I have replaced it.

Now the voltage at the IC901

Before solder all pin
Pin1--》0v
Pin2--》3.969
Pin3--》0.741
Pin4--》168.5
Pin5--》168 (soldered)
Pin6--》0
Pin7--》8.75
Pin8--》0 (soldered)

After soldered all pin
Pin1--》0v
Pin2--》2.86
Pin3--》0.741
Pin4--》166.5
Pin5--》166
Pin6--》0
Pin7--》14.94 (now stable)
Pin8--》0

C951a = 0.120v

I don't have 3.1v now

[R_J]

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

I don't have 3.1v now

Then the ic is not operating, When you blew up the ic you must have damaged more components.
Check R909/R910, D906, R916, ZD904 Check the transformer winding between pins 5,6 & 7, (should not be open)

Did you replace ic901 with a DNP005? where did you get it?

[Nish]

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

Do you think transformer could damaged?

[Nish]

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

R906 and R910 is OL, when I read with multimeter.
Transformer winding pin5,6,7 are connected

[Nish]

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

D906=0.4, r916 =5.1, zd904=0.4

[R_J]

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

Well if R909 and R910 are open, the ic will not function. (did you mean R909 instead of R906?)
The transformer is likely ok. If R916 is ok, its liely D906 is ok, zd904 is likely ok also.

[Nish]

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

Yes it's R909, I will replace and update the status.

[Nish]

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

I replace with new resistor R909 and R910 and still no 3v. Do you think it could be the caps c908 and C906. How can I test? If i remove, do you think the IC give the output?

[Nish]

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

R909 and R910 = 2ohm
I soldered R909 =5.11 , R910=3.1

[Nish]

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

I have 0.025 on D604 and D603. I measure both way ( red and black probes switched).I removed those diode and on the pad it shows that value. How come?

[R_J]

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

Why are you looking at that circuit? you need to fix the standby circuit first. Look at the schematic...there are two resistors across D604 and D603... R617 (51Ω) and R620 (51Ω)