Re: Dell 2407 wfpb no backlight
PlumBum- Did you get your 2407 Inverter board working?
bicycle6228
Member
Last Activity: 02-07-2015, 09:20 AM
Joined: 12-22-2012
Location: Salt Lake City, UT
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Re: Dell 2407WFPb Monitor - Bad Cap
I can see in your 3rd photo that R670 is burnt, and it's just out of view, but it looks like C605 has the usual chemical leakage at it's negative lead. In all, there will be about 8 to 10 components needing replacement to get this board working, some of them involving rather tricky soldering of tiny surface mount components. [url]http://home.comcast.net/~tomdempster/Dell%202405FPW%20and%202407WFPb%20Monitor%20Power%20Supply%20Board%20Repair%20Service.htm[/url]Re: Dell 2407WFPb Monitor - Bad Cap<...hoto that R670Leave a comment:
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Re: Dell 2405FPW power supply fault.
300VDC, measured across C605's terminals, with the monitor actively in display, not in standby.Leave a comment:
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Re: Dell 2405FPW power supply fault.
Forgot the schematic. Attached, but it's for the very similar 2407WFPb. There are some differences, such as R674, which is 8.25K in a 2407, but 11.3K in a 2405....Leave a comment:
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Re: Dell 2405FPW power supply fault.
C702, C711, C712, C713, C714, C715: All 6 of these capacitors are 470uf, 35V, 105°C.
D701, D702, D703: YG865C15
D704: YG802C10
These capacitors fail frequently, and also C605 (120uf, 450v, 105°C)
I have never seen any of those Schottky Barrier Diodes fail....Leave a comment:
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Re: Samsung 2433BW: 2 seconds til black
Victory. Like Ken256, I've never experienced a bad HV transformer on an inverter board, until now. I got a replacement on eBay and was encouraged right away: both secondary windings measured 1050 ohms on the new xformer, while one winding on the original xformer was 1050 ohms, and the other measured 980 ohms, both measured out-of-circuit. I put the new transformer in, and voila: up & running great. Thanks to Rtech for the suggestion.Leave a comment:
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Samsung 2433BW: 2 seconds til black
I have exhausted the resources here and elsewhere to the best of my ability.
Observations, then what I've tried:
Observations:
1) There are 4 CCFL's attached via two connectors: CN301 & CN304. It doesn't matter which CCFL cable is plugged into CN304: That cable's lamps illuminate and stay lit indefinitely just fine, provided there's no video input. It doesn't matter which CCFL cable is plugged into CN301: That cable's lamps never illuminate, with or without video input.
2) Without video input, the lamps on whichever CCFL connector is attached to CN304 are lit fine,... -
Re: Dell 2408WFPb / 2408WFP - 7 seconds to black
On a known-good, working 2408WFPb Inverter board I have, I'm measuring about 55KOhms across R015, in circuit, both polarities. I also have wondered about the purpose of the mystery 2-pin connector (CN002) on the Inverter PCB that goes to the T-Con PCB. I have no other ideas about your issue, other than this: I had a 6-CFL lamp 2407WFPb that would similarly cycle off the inverter in a few seconds, and even though all 6 lamps DID illuminate before cycling off, there was one of the 6 that when disconnected allowed the inverter to run...Leave a comment:
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Re: Dell 2408WFPb / 2408WFP - No Power
>Did you check every component to get to that one or ...
There was nothing obviously wrong via visual or resistance checks, and I could hear the ticking in T601, so I guessed the SMPS was trying to start, and I knew it wasn't an excessive load issue. I bought another 2408WFPb with a working power supply, put the two power supply boards side-by-side, focused some resistance checks on the feedback/isolator area and found differences associated w/ IC701. Out of circuit, the KA431 shunt regulator did not behave right per simple VOM checks....Leave a comment:
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Re: Dell 2408WFPb / 2408WFP - No Power
Replacing the shunt regulator, IC701 in the attached schematic, fixed my Dell 2408WFPb power supply....Leave a comment:
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Re: Dell 2408WFPb / 2408WFP - No Power
Ritalin:
I have a 2408WFP with the same no power issue, no bulged caps, shorted semi-conductors, burned components and nothing out of the ordinary.
What did you do to resolve your issue?
retiredcaps:
Answers to your questions posed to Ritalin, as pertains to the unit I have:
1) What is the DC voltage across that small cap (right of IC652)? Is it stable or fluctuating?
= 1.2 volts; very slightly fluctuating. (C716 this is)
2) IC601 is likely your SMPS chip.
a) What is the part...Leave a comment:
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