sharp lc46sb54u Troubleshoot.

[kkswim2616]

Hello!

I recently acquired this sharp lc46sb54u for little to nothing so I figured I would take it in and attempt to fix it. I am attempting to trouble shoot it and find myself lost. I replaced the power board as I originally thought it was that. I am left with the same issue as first started.

Upon pressing power there is an audible click, no picture or audio. The power and opc light blink twice together, then the opc blinks once by itself. I can force the tv on by using channel down volume up and power but i am left with no picture or audio again, just a steady green light. I have taken some voltages from the power board with the tv forced on and all the voltages seem to be cut in half of what they are supposed to be. PSON is 0, but when power is pressed it jumps to 1.5 and goes back to 0.

I will include in the post the service manual and if any pictures are needed i will upload them ASAP.

If someone could give me some direction in what voltages to test it would be greatly appreciated.

Thanks!

Ken

EDIT: Tried to upload service manual but kept freezing. Here is link

[kkswim2616]

Re: sharp lc46sb54u Troubleshoot.

https://drive.google.com/file/d/0B1L...ew?usp=sharing

https://drive.google.com/file/d/0B1L...ew?usp=sharing

Heres pictures of the boards. sorry the attachment things would still not work.

[newtothis]

Re: sharp lc46sb54u Troubleshoot.

Could do with clearer pics please, Need to be able to see and read what is on the boards

[kkswim2616]

Re: sharp lc46sb54u Troubleshoot.

it'll be nearly impossible to the get whole board with legible writing. so ill start with the power board and upload those pics.

[newtothis]

Re: sharp lc46sb54u Troubleshoot.

Yes each of the boards is preferable

[kkswim2616]

Re: sharp lc46sb54u Troubleshoot.

Power Board
https://drive.google.com/file/d/0B1L...ew?usp=sharing

https://drive.google.com/file/d/0B1L...ew?usp=sharing

https://drive.google.com/file/d/0B1L...ew?usp=sharing

https://drive.google.com/file/d/0B1L...ew?usp=sharing

https://drive.google.com/file/d/0B1L...ew?usp=sharing
Main Board

https://drive.google.com/file/d/0B1L...ew?usp=sharing

https://drive.google.com/file/d/0B1L...ew?usp=sharing

[kkswim2616]

Re: sharp lc46sb54u Troubleshoot.

with the tv forced on.

Power Board to Main Board Voltages

PSON- 1.3v
acDET-1.5v
PNL- 0v
bus5v- 3.0V
UR15v- 9.8v
UR15v- 8.9V

[kkswim2616]

Re: sharp lc46sb54u Troubleshoot.

the small cylinder fuse on the small power board is only reading 195 V it should be 240V. would that have anything to do with it?

[budm]

Re: sharp lc46sb54u Troubleshoot.

"PNL- 0v
bus5v- 3.0V
UR15v- 9.8v
UR15v- 8.9V"

The 5V is not right, same for the PNL power, UR15V.

"the small cylinder fuse on the small power board is only reading 195 V it should be 240V. would that have anything to do with it?" You use the chassis for your meter black lead, right? The incoming AC should be 120VAC between HOT (BLACK) and Neutral (WHITE). That small board is just an AC line filter board.
Are you sure your meter battery is good or it is to the correct mode since ALL you readings are way off. There is no way you can get 195V at the main AC fuse when the incoming is only 120VAC.

[kkswim2616]

Re: sharp lc46sb54u Troubleshoot.

The only way i was able to get any reading besides zero was setting it to DC, 200m Volts for the power board to main board plug.

for the ac supply I had it set to AC 200m Volts as well as thats the only setting I could get actual numbers. Maybe the batteries in it are bad. ill pick up some new ones and try again.

Thanks

[kkswim2616]

Re: sharp lc46sb54u Troubleshoot.

SO my multimeter was definitely shot. readings are quite different on a different multimeter.

PSON- 3v
ac_det- 3 v
pnl_pwr- 0v
sgnd- 0v
bus5v- 4.9v
sgnd- 0v
sgnd-0v
ur15v- 15v
ur15v- 15v

[budm]

Re: sharp lc46sb54u Troubleshoot.

So you do have problem with pnl_pwr problem. Need to find out why next.

[kkswim2616]

Re: sharp lc46sb54u Troubleshoot.

How would I go about finding out why i have nothing at pnl_pwr. There is a noise coming from the main board under the main cpu in the middle. is there anything I can jump to pnl_pwr.

Also the inverter board is receiving the necessary voltages from plug coming from the power supply, but the plug coming from the mainboard shows no voltages whatsoever.

[kkswim2616]

Re: sharp lc46sb54u Troubleshoot.

bump

[budm]

Re: sharp lc46sb54u Troubleshoot.

Per service manual page 49 5-4 block diagram, the power supply board gets the PNL_ON (>2.5VDC = ON) from CPU of the main board, then the power supply will put out 12VDC for the PNL-12V.
So if the command signal is there but no 12v PNL, then you need to do more troubleshoot of the power supply board, the service manual does not provide the diagram for the power supply because it is made by other OEM.

[kkswim2616]

Re: sharp lc46sb54u Troubleshoot.

took a shot and replaced main board and it was successful. thanks!

[budm]

Re: sharp lc46sb54u Troubleshoot.

Great and thanks for the follow-up. Was the replacement board expensive.

[kkswim2616]

Re: sharp lc46sb54u Troubleshoot.

80 dollars on ebay! luckily it worked. wasn't too bad. i only paid 50 for the tv.

[rootboy]

Re: sharp lc46sb54u Troubleshoot.

Same thing for me, and it fixed it up as well.

Thanks!!