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Is my circuitboard fried?


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I was connecting my Lilliput touch screen today, thought I would use it as UFC. But it wouldn't power on. I have moved recently, so that's why it's been disconnected from my PC. But it worked just fine last time I used it.

 

Anyway, I opened it up to see if there was something obvious wrong, since I am not an electronic expert. And it seem like there's been some sort of meltdown at the two copper coiled things, which I don't know the name for :music_whistling:

 

So any wizards out there who can draw a conclusion from the image?pcb.thumb.jpg.ef589a437cddc65c3e4019b04884c726.jpg


Edited by -odin-

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Those are just choke coils and their coated with a non-conductive conformal coating. Looks like they were coated (very sloppily) after installation.

 

Cleaning the board with a small brush and 91% isopropyl alcohol could possible yield some results, but it would be hard for me to say just by looking at a photo of the board.

 

Overall, it whoever populated the board for Lilliput performed a really crappy solder job on everything. If the electronics lab I run put out something that looked like that, they'd fire me and every employee too.

 

Is that the only circuit board in the monitor?


Edited by Total
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If the electronics lab I run put out something that looked like that, they'd fire me and every employee too.

 

Hey everybody! You're all fired because Total messed up :megalol:

 

Yes, there are one more circuitboard, but that's just for the input panel.

 

Well, I tried to clean it, but it's like some sort of harpiks or something which is solid, so I guess it has to be sanded away. But if you say it's non-conductive it shouldn't be a problem. But, maybe it is the power supply? I will see if I can get someone to check it tomorrow, because I don't have whatever-that-device meter is called. But I did check it in some sort of primitive way, that made me suspicious about it, but I can't tell you, because you'll probably laugh so much you'll wet your pants.

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Hehe, considering I perform component level troubleshooting and repair on circuit boards for medical equipment, it's kind of required I do quality work. Lives depend on it :)

 

Before you go doing anything rash -

 

Does the power light come on but the display just does not display a picture?

 

If so, then the backlight inverter is most likely bad. Most of the time, the FET's on the inverter are bad and maybe an tantulum or electrolytic cap. In unlucky cases, the transformer is bad as well.

 

If you lived in the US, I'd just tell ya to send me the monitor and I'd take a look at it for you. Could just be a bad solder joint. No way to tell without being able to look at it under my microscope.

 

Generally, in LCD monitors, you will have +5VDC, +12VDC, and -12VDC. I've seen some LCD's have the +/-12VDC set to +/- 15VDC. Just depends on the design.

 

If it uses an apater style power supply, it's probably going to be an unregulated power supply judging from the components in the lower right hand corner of the circuit board pic you posted. So, if it's 12VDC unregulated, you could see up to 18VDC if there's not a load connected.

 

Multimeter's aren't that hard to come by. Most auto parts stores carry them as do many hardware stores. You can get a pocket sized one pretty inexpensively these days :)

 

Thanks for posting the pic though. If I ever get a Lilliput monitor, then I know I'll need to go in and clean up that mess of a solder job first LOL!


Edited by Total
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Well, I got myself a multimeter, a cheap one, but it did confirm my suspicion. My DC adapter was faulty. It only delivers 1,4 instead of 12V now. But the LED light did come on so that's why I thought something was wrong with the screen itself, not the powersupply. Anyway, my screen is probably okay then, even though that goo has melted?

 

I wonder if I can use my computers powersupply instead of buying a new for the screen. Is it possble to just take the wire and connect it to a molex connector and power it from my computer? I've got a 1000w powersupply and I am only utilizing about half of that so in my head it should be theoretically possible?

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Theoretically possible, yes. However, there are more things to consider with the PSU than just the wattage - rail layout and such things need to be taken into account.

 

http://techreport.com/discussions.x/20774

 

It doesn't go into detail, but might give a few hints about what to look at for that particular application (the monitor example is about half-way through).

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looks like the chip (positioned as a diamond) @ the top centre is fried (or gunked over really bad) and something cooked between the diamond and the rectangle to its lower left


Edited by Wolf Rider

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looks like the chip (positioned as a diamond) @ the top centre is fried (or gunked over really bad) and something cooked between the diamond and the rectangle to its lower left

 

I Think that's uncleaned flux, probably rosin left over by workers. Honestly I wouldn't consider purchasing this product since I've seen this picture.

 

 

to -odin-:

You need to make sure the probes are properly connected to the power supply output, and that it's not connected to the board when taking voltage measurement.

 

If that's all done right and you still conclude the power supply is faulty, I think you can use your computer PSU as power supply. BTW, what LED are you talking about? Is there an LED on your power supply?

 

IC13 looks like an LM2576, a DC-DC step down power supply capable of generating 3A output. The black stuff near the power connector marked "FUNC****" is a fuse, "160" looks like 1.6A to me. Please check the rated output voltage and current on your power supply. The board must consum less than that much current in order not to blow the fuse. I guess you may easily find a rail with 1.6A+ margin on your 1000W PSU. Just check the spec of your hardware and do the math.

 

With the fuse as a protection and the National Semiconductor chip lying there, it doesn't look very risky to me for you to mess with your PSU. But I still want to remind you to be extra cautious with your hardware. A 1000W PSU is an expensive piece of investment, at least compared with a separate power supply.

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DSC07494.thumb.JPG.193da3785fe08ca057fffd49d7be9388.JPG

 

I hereby declare myself as a genious :smartass:

 

It worked just perfectly. Nothing wrong with my little Lilliput, just a faulty DC adapter. And yes, the LED I was talking about was on the DC adapter.

 

Now, I did get a really scary moment, because about half a second after I pushed the powerbutton on the touchscreen my computer shut down. I thoght: F**K NOOOOO! What have I done. But it had just been idle for so long it just went into hibernation - what are the odds for that???

 

Well, thanks for everyone giving me input and those of you who convinced me that the circuitboard was allright, despite the looks of it. As I mentioned, since the ledlight on the DC-adapter was on, I suspected it had to be something wrong with the screen.

 

PS! On the picture, the screen is on, it just doesn't have any input and therefor is blue.

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It's always a good feeling to do something you've never done before and it works. Now, I think I will do this with the next two screens I will get too. I'm planning to use this as a UFC and as soon as I can afford it, I will get two more as MFD screens behind the Thrustmaster MFD frames. If I can power all from my PC's power supply, it will be less cableclutter.

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Pretty slick odin. I actually had to run a short extension cord for my Lilliput since the adapter cable was too short to reach anything. I don't know if I'm brave enough to do what you did but if my adapter dies, I sure will give it a shot!

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