Sharp Aquos Quattron LC-52LE835X Totally Dead, no output voltages

[Joekhoe]

Hello all, I'm Joekhoe, a newbie here and ask your masters permissions and solutions for the problem i'm facing at the present.

I am in the middle of working on a SHARP Smart TV model LC-52LE835X from my customer, which totally dead and there's no output voltages at all at the output pins even though i have replace some of the components the output voltages remain the same with 0 volt.

The replacement as follows:
1. IC7905 : TNY264PN (first found exploded)
2. Q7915 : BT169D (exploded too)
3. IC7901 : 1608B (controller ic)
4. IC7601 : DDA014 (resonance controller)
5. R7918 : 2,2 ohm and has output for 2v
6. R7914 : 2,2 ohm

The power supply board is DPS-143BP-3A, RUNTKA 796WJQS (i attached in this thread)

The Power Factor Corrections block for main 3 bulk capacitors (C7800A, C7800B and C7800C and mosfet Q7801 has 223v output.

Resonance Converter block for Q7602 has no voltage out (0 v) however for Q7601 still has 223v.

Meanwhile for AC Det block at pin number 8 of TNY264N has 223v as well.
But at Q7915 has 5 v, C7915 has 2v, and R7918 also has 2v.

The output pins to the mainboard is as the following:
PD 1-2 = PNL 12v
PD 3-4 = SGND
PD 5-6 = S13,2v
PD 7-8 = UR13,2v
PD 9-10-11-12 = SGND
PD 13 = AC DET
PD 14 = PS ON
PD 15 = BU5v
PD 16 = PNL-POW
PD 17 = PWM1
PD 18-20-21 = NC
PD 19 = Dimmer
PD 22 = ERROR
PD 23 = PWM2
PD 24 = STB

Right now i'm still struggling to find out what the problems is and i got stuck!
That's why i'm trying to share in this forum, hope someone could give me advices and tell me what to do in order the tv could be fixed.

Thank you.

[budm]

Re: Sharp Aquos Quattron LC-52LE835X Totally Dead, no output voltages

Please provide good clear straight shots of the WHOLE top and bottom side of the power supply board, and also the pictures of the whole backside of the TV showing all the boards.

[Joekhoe]

Re: Sharp Aquos Quattron LC-52LE835X Totally Dead, no output voltages

Please provide good clear straight shots of the WHOLE top and bottom side of the power supply board, and also the pictures of the whole backside of the TV showing all the boards.

Okay, i will be back with the pictures...thanks

[Joekhoe]

Re: Sharp Aquos Quattron LC-52LE835X Totally Dead, no output voltages

Please provide good clear straight shots of the WHOLE top and bottom side of the power supply board, and also the pictures of the whole backside of the TV showing all the boards.

Okay then, i'll be back with the pictures. Thanks

[Joekhoe]

Re: Sharp Aquos Quattron LC-52LE835X Totally Dead, no output voltages

Please provide good clear straight shots of the WHOLE top and bottom side of the power supply board, and also the pictures of the whole backside of the TV showing all the boards.

Hi Budm, here are the pictures that you request. Hope they are clear to see.

I have measured the voltage when i put the power supply board together with mainboard, and there's no standby light nor the output voltages.

Thanks

[budm]

Re: Sharp Aquos Quattron LC-52LE835X Totally Dead, no output voltages

Your post #1:
"The Power Factor Corrections block for main 3 bulk capacitors (C7800A, C7800B and C7800C and mosfet Q7801 has 223v output."
What did you use for ground ref. for the meter?
Your country AC Voltage is 220VAC?

[Joekhoe]

Re: Sharp Aquos Quattron LC-52LE835X Totally Dead, no output voltages

Your post #1:
"The Power Factor Corrections block for main 3 bulk capacitors (C7800A, C7800B and C7800C and mosfet Q7801 has 223v output."
What did you use for ground ref. for the meter?
Your country AC Voltage is 220VAC?

Thanks for your reply.
Yes I did, i used 220VAC ground ref. And it's the same results when i use both legs - and + of capacitors, 223V.

[budm]

Re: Sharp Aquos Quattron LC-52LE835X Totally Dead, no output voltages

If your AC power line is 220VAC, the DCV measured between the two legs of the main filter caps should be around 320VDC, and then it should be around 380 ~ 400VDC when PFC Voltage booster circuit comes on.
When you make measurement in the hot side of the circuit, you use the negative leg of the main filter cap as the circuit ground ref. not the chassis or safety ground.
I still need to look at the schematic and pictures to give you the test points to test.

[Joekhoe]

Re: Sharp Aquos Quattron LC-52LE835X Totally Dead, no output voltages

Okay, thanks a lot for your help, i appreciate it. I'm still learning about this PFC thing. And it got me an headache . ��. I already replace the controller ic (IC 7801 = NCP 1608BD) two times, but nothing better result.

[budm]

Re: Sharp Aquos Quattron LC-52LE835X Totally Dead, no output voltages

Okay, thanks a lot for your help, i appreciate it. I'm still learning about this PFC thing. And it got me an headache . ��. I already replace the controller ic (IC 7801 = NCP 1608BD) two times, but nothing better result.

It is a waste of time to replace the PFC IC, The standby power supply section needs to be fixed first, nothing else will work until the standby power supply is working first.
BTW, PFC Voltage booster will not be running until standby power supply is working + the PS-ON is present to turn on the PFC circuit. I hope nothing gets damaged by replacing the IC too many tines.You need to understand how the circuit functions before start replacing parts.
At this point we need the correct Voltage reading on the main caps first, you report reading of 223v which is wrong.
What I need to know is what is the Voltage on the main filter caps when you measure right between 2 legs?
We cannot troubleshoot problem if the data is wrong or the measurement (using wrong circuit ground) is not done correctly.

[Joekhoe]

Re: Sharp Aquos Quattron LC-52LE835X Totally Dead, no output voltages

I will measure right between two legs of the bulk capacitors again and let you know the results as soon as i get back from my a couple days job trip.

Anyway, thanks again for your advices.

[cooltiger]

Re: Sharp Aquos Quattron LC-52LE835X Totally Dead, no output voltages

Hey there,

Just wondering if you manage to solve this issue. I trying to solve mine as well.