Re: Sharp LC-19SB280UT no Power
Ok, I went and traced that line back to Regulator portion of the Main PCB. Attached is the schematic with my readings. I got no output from the IC but had one good input. Q3001 doens't have any voltage going to the Base when it should be ~3.3V. I traced that back and found it comes from the scaler IC. And that's where I am now. I've removed the shield from top of the IC and it's a BGA IC so I think I'm done. Attached is the scat for the regulator incase I missed something and the scaler portion of the main PCB.
Edit: Added full service...
ropiemasta
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Last Activity: 01-05-2019, 09:56 PM
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Last edited by ropiemasta; 04-26-2013, 01:46 AM. -
Sharp LC-19SB280UT no Power
So I found this TV sitting out waiting to be trashed and scooped it up. Took it to my work, plugged it in and waited... No power. The standby power LED doesn't even light up. So I grapped a copy of the service manual and got to work...
Step 1: Check fuse. Fuses are good.
Step 2: Check Caps. All good. They are even rubycons.
Step 3: Use troubleshooting matrix in manual. Completed it but it only has 3 steps and ends with "Replace Power PCB" What fun is that? I wanna fix this bad boy!!!
I've got power on the board in some places and some none.... -
Re: Coby LEDTV 2326
Still got the TV? I just acquired one with a broken screen. Powers up perfectly. Let me knowLeave a comment:
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Re: rca model l37wd12yx1
Thanks. So correct me if I'm wrong in my thinking... (I've only had bout an hour and a half of sleep) When the tv is turned on, Power goes from the SMPS 1W board to the scaler board. From there it sends the on/off "signal" to the SMPS board to get the 24/12V going. Is my thinking correct? I'm looking at the Interconnect pdf that was previously attached. Thanks for the help.Leave a comment:
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Re: rca model l37wd12yx1
Just thought of something... Should I always have the standby 5V?Leave a comment:
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Re: rca model l37wd12yx1
Made any progress on this??Leave a comment:
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Re: rca model l37wd12yx1
Do you have the service manual for this TV? If so where did you get it.Leave a comment:
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Re: rca model l37wd12yx1
Yes my standby light is on. When I try to turn on the TV I get a click from the relay on the smaller power supply and the red light turns off.Leave a comment:
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Re: rca model l37wd12yx1
Hey pelota, how did you get that white gunk covering IC2 and IC3 off? Any type of cleaner or just plain scraping it off?Leave a comment:
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Re: rca model l37wd12yx1
So I found schematics for the PS. Here they are. Hope they make a lil more sense to you.
So far I have measure CON3 and got this
Pin.....Actual...."Good"
1.......~.6........11.9
2-4.....0..........0
5-6.....0..........23.39
7........3.11......3.1
I've started measuring back trying to find either 24 or 12VDC but have yet to find anything. Of course I could be using the wrong ground. If you look at the schematics Ref B37 is where I'm assuming where 24VDC "starts."...Last edited by ropiemasta; 01-11-2011, 07:44 PM.Leave a comment:
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Re: rca model l37wd12yx1
Thanks for making realize I was using the wrong ground. Using Pin 7 I got a perfect 7.5VDC. From what I can see, AC enters the connector at the bottom middle of the unit. From there follows the red and black line to the small card in the upper right hand side of the unit. From there it is picked off and sent to the main PS via the black and red lines and enters the card where the red circle is. Then makes its way to the 7 pin connector (CON3). I think I might have found a copy of the service manual for the TV so hopefully that will clear things up.Leave a comment:
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Re: rca model l37wd12yx1
Okay, I measured everything and here are my results:
Con3:
Pin 1 ~.4VDC off
~.7VDC on
Pin 2/3 - 0VDC on and off
Pin 7 - 3.11VDC on
- 0VDC off
As for Con2 there was nothing ever connected to that. However there is 5VDC at Pin 1 and 2.
IC1 is an Infineon TDA 16888. Based on the Datasheet, it says pin 2 is a 7.5V reference but I'm getting in the range of 70-80V.Leave a comment:
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Re: rca model l37wd12yx1
Hopefully these are better. Thanks...Leave a comment:
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Re: rca model l37wd12yx1
This is the back:
Front:
And overall view:
In the overall view the colors:
Red - I measured 120V coming in.
Cyan - Measured 5V
Purple - Nothing.
So that being said, the problem should be between the red and purple. Just can't figure out the flow. Thanks for the help. If you need bigger pics, let me know and I'll put bigger ones up....Leave a comment:
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Re: rca model l37wd12yx1
So was this ever taken farther. I've got the same TV with the same exact issues. I can take the pics of the TV with all cards in place and close ups of individual cards as well. I'm at a lose as to what I should be reading...Leave a comment:
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