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Old 11-11-2005, 07:54 PM   #1
Zeke
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Thumbs down Dell W1700 LCD Rev00

Same failure on two identical models of wide 17" LCD from Dell. Dell W1700 LCD Rev00.

Failure isolated to separate PCB assembly for CCFL switching power.

The CCFL switching supply assembly is marked Ambit Rev:2 T501045.00.

Blown fuses on CCFL supply assembly. Cause seems to have come from two caps on the PCB - marked: Teapo 220uF 25V.

2 caps per unit affected, total of 4 for two LCD units. Bulging on 2 caps, minor electrolyte leakage on one.



poo

I'll follow up with final repair info.
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Old 11-12-2005, 05:55 AM   #2
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Default Re: Dell W1700 LCD Rev00

what were they doing before the failure?
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Old 11-12-2005, 01:09 PM   #3
PeteS in CA
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Default Re: Dell W1700 LCD Rev00

Good Lord, when will these people figure out that a switching P/S, by whatever name you call it, demands high performance, high quality O/P caps?
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Old 11-12-2005, 01:39 PM   #4
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Default Re: Dell W1700 LCD Rev00

2 caps on a $500 lcd tv. like >$1 for good ones.

any pics?
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Old 11-12-2005, 05:29 PM   #5
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Default Re: Dell W1700 LCD Rev00

Quote:
Originally Posted by PeteS in CA
Good Lord, when will these people figure out that a switching P/S, by whatever name you call it, demands high performance, high quality O/P caps?
shhhh!
i love getting free lcd tv/monitors.
just got a gateway 19" lcd today.
and i already know whats wrong.
go ahead and use crap caps.
i love freebies!
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Old 11-12-2005, 05:43 PM   #6
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Default Re: Dell W1700 LCD Rev00

it is a good idea to start a computer equipment recycling facility. make them pay for the recycling and fix the products and use or sell them, burn the rest. according to european law products have to be recycled properly i dont know what laws you guys have in the states.
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Old 07-20-2006, 06:34 PM   #7
jduawa
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Default Re: Dell W1700 LCD Rev00

I have this tv and the tv powers on and has sound but the display is blank...would this be the result of bad caps on the backlight inverter board?? How hard would it be to replace these...i would rather spen 2 bucks on new caps than 90 on a new board
thanks
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Old 08-26-2006, 09:21 AM   #8
cnaegeli
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Default Re: Dell W1700 LCD Rev00

does anyone know if replacing these caps fixes the power on, sound on, no pic problem?
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Old 11-12-2006, 08:47 AM   #9
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Default Dell W1700 Sound, but no picture issue

I have a Dell W1700 which had the classic backlight inverted problem. Sound, power light on, but no picture. I read the forum and discovered that this is a common issue. Like most owners of the W1700, I felt that this TV/Monitor was excellent, except for the sub standard inverter board. So I had two choices. Buy a new TV monitor, or attempt to repair mine. I opted for the latter. I went to www.LCDpart.com and found that they sell the original inverted board and a remake that is supposed to be superior, both for $79 plus $10 shipping. Believing that the original board would only last 2 years or so, I decided to order the remake. The part was back ordered, but arrived within 10 days. I followed the instructions on www.lcdpart.com. They were about 95% accurate. For instance, they didn't mention you needed to remove the speakers in order to remove some screws. Not a big issue. Overall they were quite with nice pictures. It took about 45 minutes to take apart, insert the new board, and put back together. I plugged it in and my beautiful monitor was working again. Well worth the $89 and much cheaper than the $500 plus I would have need to buy a new one. Good luck to all that have the same issue.
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Old 12-04-2006, 09:53 AM   #10
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Default Re: Dell W1700 LCD Rev00

Bad experience with www.lcdparts.com Have buy a replacement for my Dell W1700 and after 15 days is dead again. I have resend a new and failure inverter to lcdparts for exchange (warranty is ok) and at today i have write 20 mail, but they not reply me and the new inverter....Where is? So my monitor is dead, amd my pocket is more light.....
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Old 12-28-2006, 03:34 PM   #11
ebrentnelson
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Default Re: Dell W1700 LCD Rev00

Was anyone ever able to fix their backlight inverter by replacing the caps and not having to replace the whole board?
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Old 12-29-2006, 10:09 AM   #12
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Default Re: Dell W1700 LCD Rev00

Well, try it. Those caps are cheap, if your in the us i think Topcat will send you them, or Bigpoe will do that for the rest of the world. It isn`t that hard, to desolder two caps on sutch a board (if the circuit is discharged safely!). It easy and straightforward. And it`s only a few bucks your can loose.
There is the changse, that nothing else is fried yet. I always try that, if i see some visible bulged or othwerwise known badcap in a bad device.
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Old 01-14-2007, 10:23 PM   #13
PedroDaGr8
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Default Re: Dell W1700 LCD Rev00

Note he said also there where several blown fuses. I am gonna look close and take care of them both. If TopCat will pm me back on the Samaxon caps.
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Old 02-26-2007, 02:16 PM   #14
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Default Re: Dell W1700 LCD Rev00

Ugh, I did the replacement on the parts. Now the backlight comes on for a few seconds (long enough to see whats on the screen etc.) then shhuts off. I can't figure out what is going on here. Any help anyone. I did notice the 16V brick is outputting 15.4ish. Could this be a problem. I dunno.
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Old 02-26-2007, 04:51 PM   #15
gonzo0815
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Default Re: Dell W1700 LCD Rev00

Test the fuses, ther are probably a few smd fuses soldered on the board, theyr silkscreened as Fxx (replace the xx with any suitable number).
Chek those for continuity and feplace them if blown (you can replace them with some wire for a short test...).
I have read about some converters, wich do have this kind of failure, if one or more of several fuses are blown.

Apart from this, may be the transistors a shorted, you can test them too for short.
There aren`t thatmutch parts on a usuall converter, thus it shoulc not that hard to it.
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Old 02-27-2007, 08:26 AM   #16
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Default Re: Dell W1700 LCD Rev00

Hmm, I'll check the two fuses directly in front of the capacitors. THose are the only two that I could find. I may post some close up pictures to get some more help. How would I go about testing a transistor?
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Old 02-28-2007, 12:10 PM   #17
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Default Re: Dell W1700 LCD Rev00

Ugh, I bridged the fuses with a piece of wire and it still does it. So it wasn't the fuses.
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Old 03-01-2007, 11:33 AM   #18
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Default Re: Dell W1700 LCD Rev00

How do I diagnose a bad transistor??
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Old 03-02-2007, 06:53 AM   #19
gonzo0815
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Default Re: Dell W1700 LCD Rev00

try to find a datasheet of the transistor in question.
Then look at the pinout.
If it is a MOSFET chek for short between gate - source , gate - drain and source drain.
But keep in kind, there are some MOSFET with integrated protection diode, thus this coul couase erounouse readings.

Bipolar transistors are similar.
For detailed instruction goolge abvouth sci faq, read the SMPS repair faq.
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Old 03-10-2007, 06:52 AM   #20
ucacmxu
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Default Re: Dell W1700 LCD Rev00

PedroDaGr8 - I have 3 W1700 with the classic backlight problem. I tested them with an LCD converter from www.lcdparts.com and they all worked fine. I then recapped the two suspect caps on the broken PCBs. The first one didn't work (probably poor soldering on my part). The second one, like yours, works for about 2 seconds then goes off. I noticed that it actually fades considerably and you can see it faintly in the dark. The third one broke so I couldn't recap it. I'll try to identify any suspect fuses and see if I have any joy changing them
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