Hitachi 43HK15W64I led tv does not light up

[poweron]

mounts electronic vestel, 17IPS72, I checked, there are 300v, but not 5v stb, is the power supply diagram?

[poweron]

Re: Hitachi 43HK15W64I led tv does not light up

Hi everyone,

[R_J]

Re: Hitachi 43HK15W64I led tv does not light up

This might be close

[poweron]

Re: Hitachi 43HK15W64I led tv does not light up

these are the voltages on U2:
pin 1 = 150v
pin 2 = 0.6v
pin 3 = 0.4v
pin 4 = 0v
pin 5 = 0v
pin 6 = 0v
pin 7 = 0.9v
pin 8 = 0.4v
pin 10 = 11v
pin 11 = 0v
pin 12 = 0v
pin 13 = 0.5v
pin 14 = 8.6v
pin 15 = 8.6v
pin 16 = 11v

the voltages measured are not stable but fluctuate by a few volts more and less

[R_J]

Re: Hitachi 43HK15W64I led tv does not light up

The voltages will fluctuate, the ic is trying to start and can not. It could be may reasons, Check all the diodes inthe secondary to make sure none are shorted, check that Q2 & Q3 are not shorted,
VCC (pin10) is too low indicating the circuit is not working correctly, the 11v is from the internal startup cell, the ic needs around 19v to operate, this voltage comes via D38 from pin 7 of the transformer. (when the circuit is working)

[poweron]

Re: Hitachi 43HK15W64I led tv does not light up

I checked all the diodes of the secondary and are good, even Q2 and Q3 are not shorted

[yokoono]

Re: Hitachi 43HK15W64I led tv does not light up

Replace C109 (47u / 100v) with a new one. Measure the tension you have on it.

[poweron]

Re: Hitachi 43HK15W64I led tv does not light up

on my C109 card is 100 / 35v, I measure on him 11v, I replaced it but nothing changed

[poweron]

Re: Hitachi 43HK15W64I led tv does not light up

there is one thing that I don't understand, how can there be vcc_main if Q2 and Q3 are not piloted, I would like to know in the initial instant just connected ac 220v what must be activated beyond + 400v?

[R_J]

Re: Hitachi 43HK15W64I led tv does not light up

I explaind it in post #5 (download the datasheet) B+ Voltage (150v) is supplied to pin1 of the ic, Inside the ic is a start-up cell and in this case a start-up Management (voltage regulator) that supplies 11.5 volts for the internal 5v and 3.3v circuits. This is used only to start the ic, after a couple pulses, C109 would be charged to about 20~25v. This voltage keeps the ic running.

In standby mode, the pfc circuit will not be active so the voltage supplied to Q2 will only be the regular B+ (325v). That is enough to supply the low current demand standby circuit.
I suspect that the voltage on pin3 is too low, (you have 0.4) I believe it should be a lot higher, so check each of the resistors, R29, R30, R31, R32. one of them might be open or high in value. They may be hard to check in circuit due to there high value (619kΩ)

You could also check the voltage on each resistor, it should start at 300v on R32 and decrease after each resistor going to the ic.

[poweron]

Re: Hitachi 43HK15W64I led tv does not light up

on my card on the line of pin 3 the components are not mounted, as perhaps it is a little different from the scheme

[R_J]

Re: Hitachi 43HK15W64I led tv does not light up

That is possible, these schematics are for many different models. If there are no components on pin3 I think the open circuit voltage should be around 4.4v (I could be wrong)
I see pin 11 is 0 volts, check the resistance to ground, IF D30 is installed it could be shorted.
Another thing to check is C172, If you have a capacitor checkor, check its value, if not, inspect it closely, if it is a square type capacitor and the sides seem to be bulged it is likley bad.
It provides a return to ground for the primary of the transformer, if it goes open you would have this result

[poweron]

Re: Hitachi 43HK15W64I led tv does not light up

yes you're right, as soon as I connect ac220v to pin 3 I have 4.4v but it goes down a little at a time until almost 0v

[R_J]

Re: Hitachi 43HK15W64I led tv does not light up

I believe that is how it should operate, check the other components I suggested. Also check the resistance of the (N2) winding of the transformer and also D3,R70 and any other parts on that line between the transformer and the vcc pin of the ic. If they are all ok, it could be a bad ic.
This circuit must work before any other parts of the power supply will turn on.

[poweron]

Re: Hitachi 43HK15W64I led tv does not light up

I checked the resistance of N2 about 1 / 1,5ohm C172 is good both in capacity and Q (over 700), at this suspicious point of U2 I tried to look for it but I can not find it online, maybe looking for the card I will be more lucky

[poweron]

Re: Hitachi 43HK15W64I led tv does not light up

I doubt, this power supply provides the voltages even if it is disconnected from the main?

[R_J]

Re: Hitachi 43HK15W64I led tv does not light up

I doubt, this power supply provides the voltages even if it is disconnected from the main?

I don't understand your question. Do you mean if you disconnect the MAIN BOARD from the POWER SUPPLY? Yes the power supply will produce the standby voltage.

[poweron]

Re: Hitachi 43HK15W64I led tv does not light up

yes you understand the question, I disconnected the power supply from the TV to take measurements, but think of it, the PSU produces the tensions but not in my case, I suspect I am on U2

[poweron]

Re: Hitachi 43HK15W64I led tv does not light up

I wanted to ask you if it was possible to find, if it existed, the equivalent of U2: FA6A30N