Sharp Aquos LC-60LE832U No Power or Standby Voltage

[Sfuchs]

Hello. My name is Sean and my neighbors home was recently struck by lighting. It came in via the phone line and pretty much took out everything on his LAN. The TV was connected to a u-verse box and so i suspect the lighting came in through a video connection. I have an electronics back ground so i offered to look at the unit. It is currently dead with zero signs of life. No power indicator at all. I removed the back cover and did the standard visual inspection for damage. To my surprise there appears to be not one bit of visual damage. I checked all the diodes, caps, ICs, transistors, etc visually on the power supply. I also looked over the main board too. I electronically checked some of the componets using a ohm meter. Including checking the fuse. Looking for obvious shorts on transistors, etc. I took some voltage reading on the primary side and everything appears normal all the way to the mosfets, etc however the low voltage side is completely dead. There is no 5, 12, 13.2, etc vdc at all. The unit was off when the strike hit. I suspect the strike did its damage to at least the 5vdc standby curcuit preventing any chance of the PSU from turning on.

I downloaded the Sharp service manual but of course they omitted the PSU schematic as its made by delta. So i could use some guidence on where to look for the components that supply the 5vdc. I also have posted images of the board here. Thanks in advance for any assistance.

[budm]

Re: Sharp Aquos LC-60LE832U No Power or Standby Voltage

Is it DELTA DPS-183BP-A?
http://www.shopjimmy.com/sharp-runtk...t-inverter.htm

So the main fuse on the power supply board is good for sure? If it is, then what DCV do you get between the two outer legs of the bridge rectifier?
You may also have some damages on the main board too, especially the HDMI chips which more likely that the surges come through the HDMI ports.

[Sfuchs]

Re: Sharp Aquos LC-60LE832U No Power or Standby Voltage

The power LED drive unit part number is RUNTKA798WJQZ. There is 169vdc coming out of the rectifier bridge. I agree on your comments about the main board. I thought i would try to get the powerr board operational and go from there. Thanks

[budm]

Re: Sharp Aquos LC-60LE832U No Power or Standby Voltage

OK, so at least you are getting the 170V for running the standby power supply section, we now need to look at the standby section next.
Details circuit tracing will be required next.
Pictures provided by SHOPJIMMY.

[ammarben]

Re: Sharp Aquos LC-60LE832U No Power or Standby Voltage

IC7905 the 5vdc standby curcuit
str-a6059h

[budm]

Re: Sharp Aquos LC-60LE832U No Power or Standby Voltage

STR-A6059h SPEC and PINOUT

[Sfuchs]

Re: Sharp Aquos LC-60LE832U No Power or Standby Voltage

Thanks all, I will check out that circuit tonight!

[budm]

Re: Sharp Aquos LC-60LE832U No Power or Standby Voltage

Fusible resistor 2.2 Ohms R7914 is for feeding the B+ from the main caps to run the IC, so check that out.
R7601 (0.1 Ohm) is also another fusible resistor for the other circuit section.

[Sfuchs]

Re: Sharp Aquos LC-60LE832U No Power or Standby Voltage

Ok so both zero ohm resistors check out. I also read 5v across pin 1 and 3 of IC7905. So it appears that circuit is working but their is no 5v at pin 15 of the J7099 connector. I assume the IC7905 feeds over to the connector......going to keep testing, any next steps appriciated

[Sfuchs]

Re: Sharp Aquos LC-60LE832U No Power or Standby Voltage

Traced 5vdc to a 2n5064 Thyristor but that is where it stops. The gate and cathode show 0v. In the attached image i hsve identifed where i am seeing 5v. Stumped on next steps....

[budm]

Re: Sharp Aquos LC-60LE832U No Power or Standby Voltage

Ok so both zero ohm resistors check out. I also read 5v across pin 1 and 3 of IC7905. So it appears that circuit is working but their is no 5v at pin 15 of the J7099 connector. I assume the IC7905 feeds over to the connector......going to keep testing, any next steps appriciated

Pin 1 is the OCP pin, 0.9V is the trip point for over current condition, so to have 5V on that pin you need to check the low Ohm resistor (Source resistor) connected to that pin 1 and GND.
Do you actually mean the VCC pin 5 and GND pin 3? if you look at the page 5 of the IC spec sheet:
VCC pin 5: Once the IC start up the running Voltage can be between 13.8~16.8VDC
If the VCC drop down between 8.9~7.3V the IC will stop running.
The minimum startup Voltage to start the IC running is 38V.
OVP once the IC is running is 26~32V.
Pin 2 is the brown-in/brown-out detection.
So when power is first applied the cap on the VCC pin is charged up through charge pump until it reaches the start up Voltage, then the IC starts running (Charge pump circuit will stop) then the Voltage of AUX winding of the transformer will be rectified and used for running the IC.

[Sfuchs]

Re: Sharp Aquos LC-60LE832U No Power or Standby Voltage

Good call, so here are the readings each pin to ground.

PIN 1 = 5Vdc
PIN 2 = 0Vdc
PIN 4 = 0.28vdc
PIN 5 = 152vdc
PIN 6 & 7 = 0Vdc

Something is a miss here

[Sfuchs]

Re: Sharp Aquos LC-60LE832U No Power or Standby Voltage

Looking for what might be pulling down the voltage. I traced PIN 4 of the IC7905 and found it connecting to a 6 pin part, pictured below. I did some resistance checks to ground and found it to be very low (700 ohms). When i tried to lift the pin, the part crumbed. Once the PIN was lifted, i checked the voltage across PIN 4 to Ground of the IC7905 and it now shows 1.5vdc instead of 0.28vdc.....and the resistance is now in the meg ohm range. I suspect the part below is toast but i have no clue what it is. I cant find it online. Furthermore should i assume the IC7905 is damaged too?

[budm]

Re: Sharp Aquos LC-60LE832U No Power or Standby Voltage

Good call, so here are the readings each pin to ground.

PIN 1 = 5Vdc
PIN 2 = 0Vdc
PIN 4 = 0.28vdc
PIN 5 = 152vdc
PIN 6 & 7 = 0Vdc

Something is a miss here

Are you sure you count the pin correctly? You cannot have 152VD at the VCC pin 5, that would have blown up the IC big time, or may be you are using the GND ref point for your meter. The cap that is connected to the pin 5 would have blown also. Pin 7 & 8 Drain pin can have >150VDC but not pin 5 VCC pin.

[Sfuchs]

Re: Sharp Aquos LC-60LE832U No Power or Standby Voltage

See image, i think its clear on how the pins are numbered and i double checked the readings....i am using pin 3 ground as my reference. Should i be using something else?

[budm]

Re: Sharp Aquos LC-60LE832U No Power or Standby Voltage

I think we need to verify the P/N of that IC.
Based on your picture, pin 5 is the Drain pin.

[Sfuchs]

Re: Sharp Aquos LC-60LE832U No Power or Standby Voltage

Image attached, looks like a TNY264PN

[budm]

Re: Sharp Aquos LC-60LE832U No Power or Standby Voltage

IC7905 the 5vdc standby curcuit
str-a6059h

I should have verify that!
So I need to look at the spec sheet next, we just wasted time due to not fact checking.

[budm]

Re: Sharp Aquos LC-60LE832U No Power or Standby Voltage

Looking for what might be pulling down the voltage. I traced PIN 4 of the IC7905 and found it connecting to a 6 pin part, pictured below. I did some resistance checks to ground and found it to be very low (700 ohms). When i tried to lift the pin, the part crumbed. Once the PIN was lifted, i checked the voltage across PIN 4 to Ground of the IC7905 and it now shows 1.5vdc instead of 0.28vdc.....and the resistance is now in the meg ohm range. I suspect the part below is toast but i have no clue what it is. I cant find it online. Furthermore should i assume the IC7905 is damaged too?

So now we know that the SMPS IC is TNY not STR, so what you fond connected to pin 4 is probably causing the problem, we now need to find out what this IC is.

[Sfuchs]

Re: Sharp Aquos LC-60LE832U No Power or Standby Voltage

Agreed....