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Old 06-13-2009, 06:54 PM   #1
maverick530
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Default Dell UltraSharp 2000FP Bad Inverter Board - Bad DT Transistors?

I have a Dell UltraSharp 2000FP 20" LCD Monitor that doesn't show anything on the screen (though I do get green lights on the front controls). I've tested both the logic board and screen in another unit and know that this inverter (part # T051023.00) is bad. Upon visual inspection, I noticed that there are 2 transistors (DT) that appear to be chipped!

I've ordered some new DT transistors form eBay, hoping this will solve the problem (replace what's visually bad first, right?), but does anybody know how to replace such a tiny part? What techniques are out there? I'm worried since the part seems soldered to the PCB and since the part itself is so tiny. Any help would be appreciated. Enjoy the pics,
Attached Images
File Type: jpg Dell 2000FP Off.jpg (153.2 KB, 86 views)
File Type: jpg Back of 2000FP (IMG_2368).jpg (155.1 KB, 125 views)
File Type: jpg Close up.jpg (152.2 KB, 203 views)
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Old 06-13-2009, 07:29 PM   #2
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Default Re: Dell UltraSharp 2000FP Bad Inverter Board - Bad DT Transistors?

Blown out, not chipped off.

Either bad lamps or transformer failed.

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Old 06-13-2009, 07:51 PM   #3
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Default Re: Dell UltraSharp 2000FP Bad Inverter Board - Bad DT Transistors?

Quote:
Originally Posted by maverick530
...that there are 2 transistors (DT) that appear to be chipped!
Chipped?!?!?! They are blown.

And good luck trying to change that small guys. You should check all that side of the inverter (especially the transformer).
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Old 06-13-2009, 10:37 PM   #4
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Default Re: Dell UltraSharp 2000FP Bad Inverter Board - Bad DT Transistors?

Quote:
Originally Posted by maverick530
I have a Dell UltraSharp 2000FP 20" LCD Monitor that doesn't show anything on the screen (though I do get green lights on the front controls). I've tested both the logic board and screen in another unit and know that this inverter (part # T051023.00) is bad. Upon visual inspection, I noticed that there are 2 transistors (DT) that appear to be chipped!

I've ordered some new DT transistors form eBay, hoping this will solve the problem (replace what's visually bad first, right?), but does anybody know how to replace such a tiny part? What techniques are out there? I'm worried since the part seems soldered to the PCB and since the part itself is so tiny. Any help would be appreciated. Enjoy the pics,
I would also suggest replacing both caps on the inverter and resoldering the transformer associated with these transistors. Wizard is right (he usually is), SOMETHING caused these to blow.

Replacement is fairly easy. I would suggest getting a kit of Chip-Quik. It's a low melting point alloy (Woods metal) that will blend with the solder and reduce the melting point. I'd load up the legs well, then use a heavy (60 Watt) soldering iron to melt the tab free. Clean the pads thoroughly, apply a little flux, hold the replacement transistor in place and solder it in using a 15 -25 watt soldering iron. This usually takes three hands, so get some help. Do make sure the tab (collector) is well soldered to the metal pad; that is the heat sink.

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Old 06-15-2009, 07:54 PM   #5
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Default Re: Dell UltraSharp 2000FP Bad Inverter Board - Bad DT Transistors?

Thanks guys. I've resoldered the transformer leads and all other leads on the Caps. I may replace the caps as well, but they look good.

I'm looking into that Chip-Quik and it's going to be about $25.00+ easy for the kit. It's a little steep for fixing only one board (I know I will be able to use it on others, but I only have one of these inverter boards to fix in this way). Is there any other more cost-effective method for removing this type of chip?
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Old 06-15-2009, 09:32 PM   #6
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Default Re: Dell UltraSharp 2000FP Bad Inverter Board - Bad DT Transistors?

Quote:
Originally Posted by maverick530
Thanks guys. I've resoldered the transformer leads and all other leads on the Caps. I may replace the caps as well, but they look good.

I'm looking into that Chip-Quik and it's going to be about $25.00+ easy for the kit. It's a little steep for fixing only one board (I know I will be able to use it on others, but I only have one of these inverter boards to fix in this way). Is there any other more cost-effective method for removing this type of chip?
Before Chip-Quik one trick was to get a piece of very fine steel wire (piano wire) and slide it under the legs while heating them. This would bend the legs up as the solder melted. Another approach would be to cut each leg after melting the solder (don't try to cut the legs without melting the solder, you'll lift the pads).

Still another way is to use a heat gun (the type used for removing paint) to heat the chip to the point the solder melts. Mask the board with aluminum foil with a small cutout around the transistor.

Or Buy Chip Quik here


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Old 06-16-2009, 09:42 PM   #7
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Default Re: Dell UltraSharp 2000FP Bad Inverter Board - Bad DT Transistors?

Before I found out about Chip Quik.

Thanks for telling me about it guys it made removing that 40 pin IC on the Panasonic effortless.

I used a cutoff wheel on my Dremel I cut the legs right where they entered the package. Once the body was gone you can simply flick the legs off the pads with a soldering iron.

Suck up any remaining solder on the pad with braid.

A steady hand is required but I replaced 15+ PS2 BA (DVD driver) chips with this method. Never cut the PCB once.

Now that I have Chip Quik though this method is stupid by comparision.

Be sure to flux the pads after removal. A common thing to do with SMT due to the small pins is to put the solder on the tip of the iron then touch it to the pin and pad.

This burns off the flux in the center of the solder. So flux must be applied to the traces.

You can pick up rosin flux cheap.
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Last edited by Krankshaft; 06-16-2009 at 09:51 PM..
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Old 06-19-2009, 07:12 PM   #8
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Default Re: Dell UltraSharp 2000FP Bad Inverter Board - Bad DT Transistors?

Ok so at that price, I had to go for the Chip Quik. Thanks for the link.

I finally had an hour and desoldered the chips with Chip Quik in a snap! It was so easy! I am a huge fan now! It was a pain in the butt getting the new tiny part soldered without soldering the leg leads together, but I finally did it by seating the collector base first, then worrying about the leads with the least amount of solder possible. That did the trick.

I didn't have time to replace the 2 caps even though I purchased them. I plugged the inverter board in, and success! My Dell UltraSharp 2000FP 20" LCD is up and running again! Thanks all for the wonderful support, yet again!
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Old 06-19-2009, 09:13 PM   #9
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Default Re: Dell UltraSharp 2000FP Bad Inverter Board - Bad DT Transistors?

Quote:
Originally Posted by maverick530
Ok so at that price, I had to go for the Chip Quik. Thanks for the link.

I finally had an hour and desoldered the chips with Chip Quik in a snap! It was so easy! I am a huge fan now! It was a pain in the butt getting the new tiny part soldered without soldering the leg leads together, but I finally did it by seating the collector base first, then worrying about the leads with the least amount of solder possible. That did the trick.

I didn't have time to replace the 2 caps even though I purchased them. I plugged the inverter board in, and success! My Dell UltraSharp 2000FP 20" LCD is up and running again! Thanks all for the wonderful support, yet again!
Replace the caps now. What if those two blew because of them?
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Old 06-23-2010, 10:53 AM   #10
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Default Re: Dell UltraSharp 2000FP Bad Inverter Board - Bad DT Transistors?

Same Issure here

did the caps and tranformers hold up after replacing the transistors?
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Old 06-24-2010, 06:46 AM   #11
maverick530
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Default Re: Dell UltraSharp 2000FP Bad Inverter Board - Bad DT Transistors?

Sorry, I don't know. I sold it. That's the problem with this business. Once it works, it leaves my shop. I hadn't heard of any complaints though, so no news is good news!
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Old 06-30-2010, 12:00 PM   #12
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Default Re: Dell UltraSharp 2000FP Bad Inverter Board - Bad DT Transistors?

i cant find those DT transistors anywhere

could you post a link to where i can find some?
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Old 10-14-2010, 04:45 AM   #13
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Default Re: Dell UltraSharp 2000FP Bad Inverter Board - Bad DT Transistors?

I'm having the exact same issue as the op, with the same monitor, and same chip on the inverter board.

http://i663.photobucket.com/albums/u...0fp_Invert.jpg

Does anyone know where I can get the transistors to see if I can get the monitor working again?
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Old 10-14-2010, 11:25 AM   #14
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Default Re: Dell UltraSharp 2000FP Bad Inverter Board - Bad DT Transistors?

Quote:
Originally Posted by tmcw View Post
I'm having the exact same issue as the op, with the same monitor, and same chip on the inverter board.

http://i663.photobucket.com/albums/u...0fp_Invert.jpg

Does anyone know where I can get the transistors to see if I can get the monitor working again?
Please do not use photobucket for images. On the 'Reply to Thread' screen scroll down to 'Manage Attachments' and use that.

Excuse the long winded lecture that follows. This is to provide a step-by-step path for others to follow.

1. Go to http://www.s-manuals.com/ It's a site with a number of good sources for information.

2. In the left column click on Marking SMD

3. On that page click on the first two characters of the marking code. In this case, DT.

4. If there are multiple lines on the target page, select the one with the correct third character AND / OR the correct package type. In this case, there is only one choice.

5. Copy the Device Name (in this case, 2SD2391) to the clipboard, go to your favorite component vendor and search for it. In this case, I went to Digikey and found they have 1686 in stock at $.77 each. Mouser has 153 in stock at $.72. If you order from Digikey, specify USPS First Class Mail shipping, which will run under $3.00. The cheapest shipping from Mouser is Priority Mail, which is several dollars more.

Of course, this applies only to the US. If you live in one of the 289 other countries you should try a local vendor.

PlainBill

Last edited by PlainBill; 10-14-2010 at 11:37 AM..
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