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jmdigges
Joined: 31 Jan 2012
Posts: 43
Location: tulsa, Ok
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| Posted: Tue Feb 07, 2012 7:20 pm Post subject: |
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Diode scale - I get .46v on the left what I think is leg 1 and I am getting 0v on leg 3 to the right, according to last datasheet I found.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Feb 07, 2012 7:24 pm Post subject: |
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Lift the 0v leg. Both if your not sure. Then test for your +5v with everything plugged in.
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jmdigges
Joined: 31 Jan 2012
Posts: 43
Location: tulsa, Ok
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| Posted: Tue Feb 07, 2012 8:07 pm Post subject: |
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Still 0v.
There is a problem in the 5v feed somewhere, with leg 3 lifted I probed the board under the leg and got 0v to BN31 pin 3. So I test all the other IC's and found some were 0v and some were ok. I am making a list. I think the good ones were fronted by diodes. Yes, when I test the input to the diodes leading to IC95 it is shorted also. It appears the 5v is shorted somewhere else on this board, of course you probably already suspected that.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Feb 07, 2012 8:14 pm Post subject: |
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| jmdigges wrote: | Still 0v.
There is a problem in the 5v feed somewhere, with leg 3 lifted I probed the board under the leg and got 0v to BN31 pin 3. So I test all the other IC's and found some were 0v and some were ok. I am making a list. I think the good ones were fronted by diodes. Yes, when I test the input to the diodes leading to IC95 it is shorted also. It appears the 5v is shorted somewhere else on this board, of course you probably already suspected that. |
We have to change your wording on some stuff because you confuse me whether your testing voltage or diode resistance.
So, if your testing voltage use the v. If your on diode test, don't use the v.
Now, what do you mean when you said "still ov"?
And yes I know the problem is in the +5v line and thats what we are trying to find.
So what legs are lifted on ic98?
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jmdigges
Joined: 31 Jan 2012
Posts: 43
Location: tulsa, Ok
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| Posted: Tue Feb 07, 2012 8:27 pm Post subject: |
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The 0v referred to the input voltage at BN31 pin2 and 3
Both legs 1 and 3 are lifted. I am using the diode test on the board. I use voltage test to check for voltage input at bn31. Both tests (dc voltage and diode) show voltage that's why I used it. I will drop it off of future diode tests. I get 0 when I test leg 3 of the all IC's to pin 3 on BN31.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Feb 07, 2012 8:35 pm Post subject: |
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Why 0v at pins 2 and 3 on BN31? You had +1.90v at ic91 output on the regulator board which is directly connected to BN31.
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jmdigges
Joined: 31 Jan 2012
Posts: 43
Location: tulsa, Ok
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| Posted: Tue Feb 07, 2012 8:56 pm Post subject: |
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The power is dropping almost immediately when BN31 is plugged in. I am trying to get the peak during power on. I just retested BN31 pins 2 and 3 and I see about 2.5v, better than 1.90v. Ic98 may have affected that reading. I also retested IC 91 and got 2.5v there. I may have not have had BN94 lead to Video seated at the time. It is adjacent to CN31 and I may have move it a little when I pulled BN31.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Feb 07, 2012 9:36 pm Post subject: |
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Ok. So we are going to have to start disconnecting components until that voltage comes up to the +4.95v. There are a lot of things connected to it so it may take a while or you may get it quick.
I would start with locating L905 and remove it. Then test your voltage again. If still not up to normal then I would start lifting leg 3 (input) on those regulators you have been testing. Do a voltage test every time you lift a leg on one.
You dont need to lift a leg on ic93 because when you lift ic89 leg 3 it also disconnects ic93.
Let me know what you find.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Feb 07, 2012 9:47 pm Post subject: |
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I just looked something up and I want you to disconnect ic97 leg 3. It's one of those regulators. Then test your voltage.
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jmdigges
Joined: 31 Jan 2012
Posts: 43
Location: tulsa, Ok
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| Posted: Tue Feb 07, 2012 11:02 pm Post subject: |
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Somewhat better BN31 Pin 2 and 3, 3.35v; receiver stayed on but no screen display. Those little guys are a bear to unsolder. they act like they're welded.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Feb 07, 2012 11:08 pm Post subject: |
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And what do you have disconnected so far?
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jmdigges
Joined: 31 Jan 2012
Posts: 43
Location: tulsa, Ok
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| Posted: Tue Feb 07, 2012 11:10 pm Post subject: |
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Just the two ic's we unsoldered ic98 leg 1 and 3, and ic97 leg 3
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Feb 07, 2012 11:14 pm Post subject: |
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Alright, keep going. Try that inductor next, L905.
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jmdigges
Joined: 31 Jan 2012
Posts: 43
Location: tulsa, Ok
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| Posted: Wed Feb 08, 2012 12:00 am Post subject: |
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Im dragging my feet, that guy is really small. Are there any other Ic's in the path that could be done first? I'm not sure as how successful I can be removing and resoldering that inductor. I think I have a smaller iron and I have a real nice lighted magnifier.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Wed Feb 08, 2012 12:10 am Post subject: |
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Well you can go back to the regulators and remove the input leg of each one but I have a feeling we are going to have to remove some of these inductors also. Some of these ic's receive 3 voltages each and more then likely all 3 voltages will have to be removed to see the 5v supply voltage come up to normal.
I'm fearing though that 1 or more of those multi leg ic's are blown out and I'm guessing you won't be able to change them.
Maybe you just want to price an HDMI board now just to see where your at.
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jmdigges
Joined: 31 Jan 2012
Posts: 43
Location: tulsa, Ok
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| Posted: Wed Feb 08, 2012 12:21 am Post subject: |
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The IC's are not a problem, I can easily do those. The inductor is quite a bit smaller and I can do it, but I would prefer to do the IC's first. I've soldered many whole boards before, I don't have a problem with that. I also, can see that both IC's brought the voltage up, and I was already thinking it may take several to get back to 5v. I can measure them like we did on IC98 and go with the lowest ones first. What do you think?
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Wed Feb 08, 2012 12:27 am Post subject: |
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When I say ic's I mean the 100 or 144 pin ics. Are you able to change those?
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jmdigges
Joined: 31 Jan 2012
Posts: 43
Location: tulsa, Ok
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| Posted: Wed Feb 08, 2012 12:47 am Post subject: |
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No, not those!!!
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Wed Feb 08, 2012 12:53 am Post subject: |
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Well the only way to know for sure is to disconnect those regulators and probably remove a few inductors. So if you want to keep going you can start with the regulators.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Wed Feb 08, 2012 12:58 am Post subject: |
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If you do decide to keep going I need you to start making a list of which regulators or inductors you disconnect and the voltage change on that 5v line.
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