lp2407 aka fpd2485W No Power
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Re: lp2407 aka fpd2485W No Power
PlainBillFor a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.
Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.Comment
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Re: lp2407 aka fpd2485W No Power
Replaced that voltage regulator and now the monitor is powering up and displaying video. Just waiting for the replacement caps for the video board. There is still a low pitched buzzing sound on the power board, is this something i should be concerned about?Comment
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Re: lp2407 aka fpd2485W No Power
After recapping my power supply, I thought my feeble attempt at repairing my monitor was lost. The power supply wasn't the problem. But by successfully recapping the power supply and not losing a limb in the process, I found the confidence to push ahead. This thread saved me as Plainbill's diagnostic steps to test the 5 regulators on the signal board lead me to find that I had two bad regulators. I'll report back after installing the 3.3v regulators. Thanks to knoxrebel and PlainBill for helping diagnose.Last edited by justincase102; 11-07-2011, 12:06 PM.Comment
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Re: lp2407 aka fpd2485W No Power
I have the same issue- no signs of life at all from the monitor. I noticed a few bulging caps on the power supply, inverter and signal board and replaced them all. I also replaced ALL the caps on the power supply just to be sure. I did make a small error in ordering caps so for the 2x 450uf 35v 125C i got the same but rated for operating temp 105C, installed them anyway.
When I plug in the power supply, I've measured 164v across the big 450v cap and I checked the fuse and its ok obviously.
However, when I check the voltage coming off the power supply (blue area in http://i.imgur.com/X9yaF.jpg)
I'm getting nothing, 0v, from all leads.
I'm not sure what my next step should be, any advice would be greatly appreciated. I'm close to sending it in somewhere or try and order new power supply if possible.Last edited by drdenner; 11-09-2011, 06:03 PM.Comment
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Re: lp2407 aka fpd2485W No Power
I have the same issue- no signs of life at all from the monitor. I noticed a few bulging caps on the power supply, inverter and signal board and replaced them all. I also replaced ALL the caps on the power supply just to be sure. I did make a small error in ordering caps so for the 2x 450uf 35v 125C i got the same but rated for operating temp 105C, installed them anyway.
When I plug in the power supply, I've measured 164v across the big 450v cap and I checked the fuse and its ok obviously.
However, when I check the voltage coming off the power supply (blue area in http://i.imgur.com/X9yaF.jpg)
I'm getting nothing, 0v, from all leads.
I'm not sure what my next step should be, any advice would be greatly appreciated. I'm close to sending it in somewhere or try and order new power supply if possible.
1. A cap was put in backwards - don't laugh, it happens.
2. You formed a solder bridge between the leads of a capacitor.
3. The SMPS controller has died.
I'd suggest you investigate the first two yourself. If you don't find anything, take good, sharp, well lit pictures, one of the top and one of the bottom of the power supply and attach them to your next post using 'Manage Attachments'. From that we can suggest the next troubleshooting steps.
PlainBillFor a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.
Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.Comment
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Comment
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Re: lp2407 aka fpd2485W No Power
3) SMPS = switch mode power supply.
PlainBill is interested in the SMPS controller (IC). It looks like it is mounted on the small pcb board that is mounted vertically next to the biggest cap.
On that board should be a 8 pin IC. A picture of that board will help.
4) Did you change the little cap next to the big 150uF, 450V cap as well? I know you wrote "ALL", but some people may missed that one.
What is the DC voltage across that little cap?
5) I see one Panasonic replacement and I think the others are Nichicon? Is that correct?--- begin sig file ---
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We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.
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Re: lp2407 aka fpd2485W No Power
Datasheet is at
http://pdf1.alldatasheet.com/datashe.../SG6902SZ.html
It looks like 16V DC is the typical startup threshold (min = 15, max = 17V DC). So it looks like the voltage across the small cap is okay.
You can try to carefully measure the voltage on Vdd. Try not to short out the pins as the chip as a lot of pins.Last edited by retiredcaps; 11-09-2011, 08:57 PM.--- begin sig file ---
If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.
We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.
Please do not post inline and offsite as they slow down the loading of pages.
--- end sig file ---Comment
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Re: lp2407 aka fpd2485W No Power
Ok so I measured the voltage on the IC and its 15.87v also.
But something weird happened the first time I tried- I think I may have shorted it accidentally, but then the power supply started humming and I measured voltage coming off of it, 5v and 23v. I turned it off and then on, but again no voltage.Comment
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Last edited by retiredcaps; 11-09-2011, 10:12 PM.--- begin sig file ---
If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.
We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.
Please do not post inline and offsite as they slow down the loading of pages.
--- end sig file ---Comment
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Re: lp2407 aka fpd2485W No Power
Ya but those were intentional since in those spots the trace came off the board so I just tested to make sure the trace was joined to a neighbouring pin and bridged the pins for a better connection. They were already joined electrically. I know the basics of electronics.Comment
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For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.
Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.Comment
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Re: lp2407 aka fpd2485W No Power
Good Morning,
This is my first time posting on this forum, so I apologize if I'm not following protocol. I am kind of a novice when it comes to component level repair, but I used to do a lot of power jack repairs on laptops a few years back, so I am very comfortable with a soldering iron.
I am having the same issue that knoxrebel was. My unit was turning on until recently and now it does nothing when I plug it in except make some noise. I would describe the sound as being similar to turning on an old CRT monitor, but quieter. I's coming from the power board near the big capacitor. It may be normal and may have happened ever since I bought it and just never noticed it, but I thought I would at least mention it.
I do not notice any bulging from the capacitors, and I don't see anything that looks unusual.
I ran through the diagnostics that PlainBill had knoxrebel go through and these are the results that I got back:
voltage across big cap(yellow circles) (C854) - 160v
voltages to inverter board (blue circle):
0
0
0
5.1
0
0
26.3
26.3
voltages across regulators (3 - 4)
chip 1: 5.1 - 3.3
chip 2: 1.25 - .42
chip 3: 5.1 - 1.3
chip 4: 5.1 - 4.1
chip 5: 3.3 - 1.8
Based on PlainBill's response to knoxrebel's voltages, I know that the voltage regulator labeled at chip 3 is bad, but chip 4's voltage is also a little off and the voltages to the inverter board is slightly off too.
Is chip 4 within tolerance or does it need to be replaced too?
Are the voltages coming from the power board within tolerance, or do I have a problem there too?
Thanks for the help!
- TComment
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