Power light comes on dell logo appears, test icon appears screen goes blank. When screen is showing logo ccfl's light, when screen goes black they go off. Any thoughts?
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Re: dell 1740fpt
Yes you can see either logo or wall paper, with bright light. Checked all caps, good. Transistors appear good, no shorts, or burned resistors.Comment
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Re: dell 1740fpt
You have 2 seconds to black. Possible causes in no particular order are
a) bad caps
b) bad inverter transformer
c) bad ccfl
d) bad ccfl wiring
See (starting with post #13) for all the details ...
https://www.badcaps.net/forum/showthread.php?t=10419
edit: How are you checking the caps and concluding they are good? ESR meter?--- begin sig file ---
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Re: dell 1740fpt
Replaced all caps as I have no esr. And I guess I have not got permission to post attachments, as the faq says I should have a tab to select and I do not see one?Comment
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Re: dell 1740fpt
My mistake looked in wrong place. I am new to this forum structure, will try to be more observant. here are pics I have used, to show my boards.Attached FilesComment
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Re: dell 1740fpt
You sure that's not a Dell 1704FPT not 1740FPT? I couldn't find any manuals or drivers for a "1740" at Dell
If it is a 1704FPT then the solution is the same as the one found in this recent thread https://www.badcaps.net/forum/showthread.php?t=11807
The inverter comes with a 22uF 50v cap, when it should be a 2.2uF 50v. The caps are mismatched. In my case it took out the inverter transformer too.Comment
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Re: dell 1740fpt
Thought it was just me that couldn't open them
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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: dell 1740fpt
Ok let me try this agin it is a dell 1704fpt not a 1740fpt. duh! Thats why I check my replacement parts more than once before I change them. I replaced all the caps with new capxon, tit, for tat, whatever value and style the board had is what I replaced it with, regardless as to if it checked good with my vom. Yes I know thats not a certain way to check but at this point all I can afford, caps are cheap compared to the uncertain check of a vom when I try to problem solve a odd board problem. As for the pic I will check resolution and re attach. Right now I am away from my main storage drive. Thanks for your patience while I try to learn.Comment
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Re: dell 1740fpt
Capxon doesn't have a very stellar reputation here. A list of good quality low ESR capacitors is here
https://www.badcaps.net/forum/showthread.php?t=2280--- begin sig file ---
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Re: dell 1740fpt
Ok, good. I just repaired a Dell 1704FPT 2 days ago. In my case the inverter section of the board had a 22uf 50v capacitor, when it should have been a 2.2uf 50v. (located at C112) Those 2 small caps need to be matched. (2.2uf 50v)
Here's what fixed it for me......
1. Replaced capacitor at C112 (the 22uf 50v) with a 2.2uf 50v
2. Replaced the transformer at T102. (ring tester showed primary had shorted)
3. Replaced resistor at R125 (even though it tested good, it had really gotten hot and the whole area was brown) This is probably optional
Good luckComment
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Re: dell 1740fpt
Why did it have the wrong caps had someone been there before ye. I will look at mine and see thanks for the info.Comment
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Re: dell 1740fpt
I just got a dead one of these as well. Won't power up at all.
I see three leaky caps in the upper left. I figure I'll replace those.
The two caps at the bottom are also different, 2.2 left 22 right, should I replace the right one?
And since it won't power at all, should I check anything else or would those caps be the most likely culprit?
Thanks!Attached FilesComment
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Re: dell 1740fpt
Capxon makes some of the worst quality caps around. My standard answer below (regulars may skip).
https://www.badcaps.net/forum/showpo...84&postcount=3
Check the fuse. A good fuse should measure less than 1.0 ohms.And since it won't power at all, should I check anything else or would those caps be the most likely culprit?--- begin sig file ---
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Re: dell 1740fpt
Fuse tests good. I'll order up some caps. Would it be wise to replace all the larger 470uf 35v ones as well?Comment
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Re: dell 1740fpt
Yes if they are capxon, There are other tests you might want to do first - this is only a 17inch screen if the ccfls or transformers have gone how much would you spend to repair it? Please can you update your profile with Country and mains voltage.
Next test would be voltage on the BIG cap CARE required as HIGH voltage. All connected up and switched on set meter on 600vDC put red probe on positive leg and black probe on negative leg and post results.
Another easy test is on the inverter transformers secondary windings.
Power off ( for 5 minutes at least) Set Meter on 2000 ohms and measure secondary windings cant see the pin numbers but is the two on the outer ends -Post resultsPlease upload pictures using attachment function when ask for help on the repair
http://www.badcaps.net/forum/showthread.php?t=39740Comment
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