Re: Dell 1901fp
Sorry for keeping this thread rolling, I'm sure some of you trying to help are frustrated. I've been waiting for parts and replaced them to see if that helped.. all caps are replaced, and all my voltages are unchanged.
I'm kind of looking for a theory opinion here. Looking back at all that has come out of this so far, we have figured out that my output connector (when not connected to the logic board) has the correct output voltages. Once connected, the logic board from both screens is drawing a load (one that it doesn't like), which to me seems to...
littlski717
Member
Last Activity: 12-12-2011, 10:10 AM
Joined: 11-15-2011
Location: Illinois
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Re: Dell 1901fp
Ok cool. I will look into pricing to replace all of the caps, and see if it's worth just buying a replacement board or replacing the caps.
I would also guess that these caps are the most common problems in this case, correct? what else could there be that may cause the same problem? -- just from all of your experiences.Leave a comment:
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Re: Dell 1901fp
I have actually replaced all of the bigger caps (excluding the giant one) on both boards. I am currently working on both boards simultaneously, but I am only talking to you guys about one, because I can survive if I just get one running. Now in regards to those startup caps, is there any way possible someone could willingly point out on my pics in this thread which caps those would be? That would be awesome if you could.
BTW, do I have to use the same logic board to test both PS boards? Or can I work with each PS board and logic board together as they...Leave a comment:
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Re: Dell 1901fp
***I don't know what the deal is, but when I plug it in after about 30 seconds, I start to hear a high pitch whining noise.***Leave a comment:
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Re: Dell 1901fp
Yeah, when I did this previously, I used the pins on the bottom of the board with the board connected and it never got close to 5V. That is when I was getting 2.86V...Leave a comment:
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Re: Dell 1901fp
Alright, I did this. I showed a constant 5.16V on the output connector on both blue and purple, while is was disconnected from the logic board....Leave a comment:
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Re: Dell 1901fp
I don't mean any disrespect by this, I know you guys are trying to help, but I am not a total newb when it comes to electronics. I am actually a EET major in my junior year, but I haven't messed with this type of board. And yes, I know that makes me nowhere near a professional, as a matter of fact, i'm far off from most of you i'm sure. Please forgive me if I ask questions, but this is all actually very interesting to me, so I ask questions to learn for the future.
And yes, I know how to use a DMM to make a measurement. lolLeave a comment:
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Re: Dell 1901fp
No need to apologize, I read that waaaay wrong. lol...
so here's the new readings.
Pin 1: 867mV
Pin 2: 0.3mV
Pin 3: 0.8mV
Pin 4: 0.3mV
Pin 5: 0.3mV
.... something seems really strange.Leave a comment:
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Re: Dell 1901fp
So I re-measured, and pin 5 which is furthest to the right with the tab on top, is giving me a reading of 0.09mVLeave a comment:
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Re: Dell 1901fp
***UPDATE***
Both the blue and purple wires still have 5.18V at the harness that plugs into the logic board.Leave a comment:
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Re: Dell 1901fp
That is correct. When I didnt have the adapter connected, that's what I got.
With the adapter connected and pulling measurements directly off of the bottom of the logic board at the connector pins, I got roughly half of that. I will re-measure now and report back....Leave a comment:
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Re: Dell 1901fp
Okay, here's what I got.
on the 5.15v pins, they are both 2.85V.. the bri-out pin, is 2.15V.
I replaced the four larger caps on the board and none of them were bad. Someone earlier had mentioned the smaller caps by the big cap. but they don't seem to be bad either.Leave a comment:
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Re: Dell 1901fp
Just to double check, you want me to measure the voltages on the logic board pins from the bottom of the board, where the adapter connects from the the power supply board, right?
ps. I hope that made any sense. lolLeave a comment:
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Re: Dell 1901fp
Okay, here are the measurements -- hopefully I explain this good enough......
1st regulator w/ metal flap (pins from left to right with flap on top)
part# FAN1537PAC
pin 1: 2.93v
pin 2: 0v (slowly climbs by a hundredth of a mV)
pin 3: 0.2mV
pin 4: 2.22V
pin 5: 1.79V
2nd regulator (from left to right with single pin on top)
part# AH3324985
pin 1: 0.3mV
pin 2: 0.3mV
pin 3: 10mV
top pin(4): 0.3mV
----HOPE THIS HELPS SOMEONE!! ---...Leave a comment:
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Re: Dell 1901fp
Yeah, I need someone that has played with more boards to give me an idea where to start attacking this. I can't find any schematics online, and I think there may be something not going right on the output connector. Should I for sure be getting 5.17 on 2 of the pins and 0's on the others? I know the ground pins should be 0, but the other ones are the ones I am not sure about.
Even if someone could point me in the direction of those caps you talk about, would help me. What is the voltage they should be at as the board is plugged in?Leave a comment:
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Re: Dell 1901fp
alright, that helps out some.
So is that cap basically for a soft turn-on? And by the way, Thank you!Leave a comment:
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Re: Dell 1901fp
What do you mean start-up caps? I'm assuming they are on the power board -- but which ones are they?Leave a comment:
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Re: Dell 1901fp
Here ya go!...Leave a comment:
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Re: Dell 1901fp
I did crop it. Unfortunately this is where mac sucks compared to windows. It cuts parts of the pics off. I will try again right now.Leave a comment:
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Re: Dell 1901fp
Here are the pics of the logic board....Leave a comment:
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