Pulled an LG 47lk520-ua LCD from the dump and plugged it in. Red STBY LED is lit, but dims when power button is pressed. No picture or sound. Suggestions on where to start?
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Re: LG 47lk520-ua No picture, STBY LED dims
Post good clear pictures so we can see what we are dealing with it.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809 -
Re: LG 47lk520-ua No picture, STBY LED dims
Took me a few days to get back to this. The last picture is the backside of the power supply.Attached FilesLast edited by ahickman; 11-12-2012, 09:54 AM.Comment
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Re: LG 47lk520-ua No picture, STBY LED dims
anyone?Comment
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Re: LG 47lk520-ua No picture, STBY LED dims
Test standby voltage. If you're not sure which pin is standby voltage, post a picture of the legend near the connector running to the main board from the PSU.Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.Comment
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Re: LG 47lk520-ua No picture, STBY LED dims
3.49 vdcComment
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Re: LG 47lk520-ua No picture, STBY LED dims
Is it indicated as 5V?Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.Comment
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Re: LG 47lk520-ua No picture, STBY LED dims
No. It is marked as 3.5 VDC. Tested the 12 VDC (12.40 VDC) and the 20 VDC (21.8 VDC) supplies. Noticed that the red STBY LED cycles through bright/dim at about a 3 second interval. No changes in the voltage readings. Also noticed that when PWR is hit again, the PS voltages return to 0 VDC, excepting STBY which remains at 3.5 VDC. I then looked for voltage at F1 on the T-con board. No voltage present on either side of the fuse. Checked the one voltage regulator that I see on the main board and saw 2.5 and 3.2 on the pins.Comment
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Re: LG 47lk520-ua No picture, STBY LED dims
What is the marking on that regulator? I am thinking main board issue now. PSU seems fine.Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.Comment
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Re: LG 47lk520-ua No picture, STBY LED dims
On the reverse side of the main board, I found a regulator that reads:
Pin 1 = 0.00 VDC
Pin 2 = 1.81 VDC
Pin 3 = 3.30 VDC
Shouldn't pin 2 be 1.25 VDC if this is a 1117 regulator?Comment
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Re: LG 47lk520-ua No picture, STBY LED dims
What is the part code on it, as well as the other one?Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.Comment
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Re: LG 47lk520-ua No picture, STBY LED dims
OK, here are the details:
IC410
PN = 111KG 1117
Pin 1 = 3.68 VDC
Pin 2 = 4.94 VDC
Pin 3 = 6.85 VDC
IC411
PN = 111KG 1117
Pin 1 = 3.71 VDC
Pin 2 = 0.00 VDC
Pin 3 = 6.85 VDC
IC3703
PN = EH17K 110n10
Pin 1 = 0.00 VDC
Pin 2 = 1.27 VDC
Pin 3 = 3.30 VDC
IC404
PN = 111KG 17 18
Pin 1 = 0.00 VDC
Pin 2 = 1.81 VDC
Pin 3 = 3.30 VDC
IC402
PN = AZ2940025E1 112J72
Pin 1 = 3.32 VDC
Pin 2 = 0.00 VDC
Pin 3 = 2.51 VDCComment
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Re: LG 47lk520-ua No picture, STBY LED dims
IC411 looks a little odd. Is pin #2 definitely 0V?Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.Comment
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Re: LG 47lk520-ua No picture, STBY LED dims
Re-tested:
IC411
PN = 111KG 1117
Pin 1 = 3.71 VDC
Pin 2 = 4.95 VDC
Pin 3 = 6.85 VDCComment
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Re: LG 47lk520-ua No picture, STBY LED dims
That seems more realistic, it is creating 5VDC from 6.85V; 3.71V + 1.25V = 4.96V (you have 4.95V.)Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.Comment
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Re: LG 47lk520-ua No picture, STBY LED dims
Finally found a service manual and started with the troubleshooting steps (page 54). Measure 2.8 VDC on Pin 8 of IC405 which should be 3.3 VDC. Also looked at voltage on Q409 and found 0.0VDC on the output. When I shorted the input to the output pins of Q409, the blue LED on the top of the set turned on. Measured 9.5 VDC on the F1 of the T-con. Progress, but not there yet. Need to find the replacement for IC405. The part number on the chip is AOZ1073AIL-3. Anyone suggest a replacement?
http://elektrotanya.com/lg_47lk520-u.../download.htmlComment
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Re: LG 47lk520-ua No picture, STBY LED dims
Anyone?Comment
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Re: LG 47lk520-ua No picture, STBY LED dims
Went ahead and bought a replacement motherboard owing to ShopJimmy's 15% discount code offered. Fired right up. Would have preferred to fix it, but too many others to troubleshoot in the garage! Thanks for all that helped.Comment
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Original T-con:
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First replacement T-con:
I thought it might be t-con and ordered new t-con from china(supposedly tested)... -
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Problem
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