Sharp LC-46SB57UN no power

[NUTIN2LUZ]

Hey folks. I am trying to repair this TV and don't have any standby output (5V) on the power supply DPS-286AP to the main board. I have replaced IC7905, R7918, R7914, and D7908 as to Shopjimmy repair kit and I still don't have any standby output (5V). Any help would be greatly appreciated.

[budm]

Re: Sharp LC-46SB57UN no power

This one is tough to work on due to the heatsink.
What DCV do you have measure right at the two legs of the main filter cap in the primary side? You will have to do the measurement on the bottom side of the board.
I assume the fuse have been checked already.

[NUTIN2LUZ]

Re: Sharp LC-46SB57UN no power

This one is tough to work on due to the heatsink.
What DCV do you have measure right at the two legs of the main filter cap in the primary side? You will have to do the measurement on the bottom side of the board.
I assume the fuse have been checked already.

I've got 164VDC. Fuse is good.

[budm]

Re: Sharp LC-46SB57UN no power

Check the fusible resistor for feeding the B+ to the SMPS IC (P/N of the IC?).
Check the snubber diode, the secondary side diode for the STBY P.S.
Check the DCV on the startup caps in the primary side, measure right at the two legs of the cap, do not use chassis as the GND ref for the meter.

[NUTIN2LUZ]

Re: Sharp LC-46SB57UN no power

Fusible resistor original was 2.1 ohms and replaced with 5.6 ohm resistor (Shopjimmy repair kit)
Snubber diode .230 slightly going up
I've checked the ESR on C7918 and got 5.4 1uF 100V which I believe is high. Didn't check the voltage yet, but I'll be changing that cap And get you the voltages.

[budm]

Re: Sharp LC-46SB57UN no power

I would replace both of the startup caps at the same time.

[NUTIN2LUZ]

Re: Sharp LC-46SB57UN no power

ok I got on C7915 voltages goes from 5.5V to 5.66V. The voltages just keeps jumping between those voltages. C7918 voltages goes from 2.6V to OL.

[NUTIN2LUZ]

Re: Sharp LC-46SB57UN no power

Bump

[koolkevin1107]

Re: Sharp LC-46SB57UN no power

I'm having the same problem. I replaced my components with the shopjimmy repair kit. still nothing. Nutin2luz did you figure it out yet?

[koolkevin1107]

Re: Sharp LC-46SB57UN no power

I should add that prior to me repairing it with the kit, I would get the red standby light. Now, i don't get the light at all. I checked the obvious things such as the fuse and caps. Everything is in range.

[NUTIN2LUZ]

Re: Sharp LC-46SB57UN no power

I'm having the same problem. I replaced my components with the shopjimmy repair kit. still nothing. Nutin2luz did you figure it out yet?

No I have not repaired this power supply yet.

[fixertech]

Re: Sharp LC-46SB57UN no power

I have problems with R7914 resistor, I check and is open , I change it, but it burns twice , any idea or help finding the problem?

the new resistor is 2.2 Ohms 5 %

[budm]

Re: Sharp LC-46SB57UN no power

I have problems with R7914 resistor, I check and is open , I change it, but it burns twice , any idea or help finding the problem?

the new resistor is 2.2 Ohms 5 %

It blew open circuit because you have shorted component on the output side of the R7914, check the resistance of the STBY SMPS IC7905 PIN 8 and Primary circuit GND for very low resistance.

[budm]

Re: Sharp LC-46SB57UN no power

Correction, is your IC TNY264? If it is, then it will pin 6 and GND.
https://www.badcaps.net/forum/showth...656#post688656

[budm]

Re: Sharp LC-46SB57UN no power

Sorry, Typo, it is pin 5 the Drain pin.

[Shane711]

Re: Sharp LC-46SB57UN no power

No follow up NUTIN2LUZ? Well anyways I have a different problem. My fuse blew and I had to remove the heat shield. Under the heat shield I have a toasted capacitor. I have no idea what the value used to be and I can't find any diagrams online. C7816. At this point I have to guess what the value is. That capacitor and the fuse seem to be the only problems.

[Shane711]

Re: Sharp LC-46SB57UN no power

I put in a 681k by 2KV because that is what I had and replaced the fuse. TV is working but I still need to know the correct value if any one has any idea. Thank you.

[budm]

Re: Sharp LC-46SB57UN no power

That looks to be snubber cap, typical value will be 220 ~ 330 pf 2KV

[Shane711]

Re: Sharp LC-46SB57UN no power

I looked up online "snubber capacitor" and it says there is suppose to be a resistor in series with it, no resistor. It does have a diode in parallel with it and it has a diode and transistor in series with it. My first thought was a surge protector but why is it in parallel with a diode, that does not seem like a surge protector. Any ways I may have a board coming to me where I will be able to see what the part is. I have offered someone to fix there board for shipping cost just so I can see what the original part is. So I am doing someone a favor and getting what I need at the same time. I will know in 3 to 5 days.

[budm]

Re: Sharp LC-46SB57UN no power

Not all snubber circuit will have resistor in series, for example snubber caps C7822, 7824 for the MOSFET Q7805/7808 are connected in parallel with the Source and Darin pin of the MOSFET's.
Cannot tell more until I see the bottom side of the board. Is your board exactly the same model and revision as OP?
is that the MOSFET or Diode next to that burnt cap?
Looking at OP pictures: https://www.badcaps.net/forum/attach...8&d=1426262140
That C7816 is the snumber cap for the diode D7806, the cap is connected in parallel with Anode and Cathode of the Diode.