Dell 2407WFPb Monitor - Bad Cap

[retiredcaps]

Re: Dell 2407WFPb Monitor - Bad Cap

Checked, but not sure of the result I got:

• R669 - 15k ohm, but post #77 says this should be 1k.
• IC601 - Doesn't seem shorted. Varying resistances between pin pairs. I'm guessing this is OK as I suspect a failure would mean no resistance between pairs/visible damage like IC651, or no continuity at all.

1) What is the color code for R669? Use

http://www.hobby-hour.com/electronic...calculator.php

to verify.

2) Manufacturers can and have made revisions to their boards while keeping the same lcd model number.

3) The readings indicate that IC601 doesn't appear to be shorted.

4) One correction. Shorted means having continuity. Not shorted means having no continuity.

[selldoor]

Re: Dell 2407WFPb Monitor - Bad Cap

I'm sure selldoor will have comments once the UK timezone comes around.

Yes - great pics - totally missed this thread till now and its too late -eyes are bleary/weary I'll look again tomorrow, though with pics that size I'm sure any probs will have been spotted.

[sabretooth]

Re: Dell 2407WFPb Monitor - Bad Cap

Ahh, my bad. My definition of shorted was 0 resistance.

R669 is surface mount! and a correction, I'm actually getting 41.5k across it.

[retiredcaps]

Re: Dell 2407WFPb Monitor - Bad Cap

R669 is surface mount! and a correction, I'm actually getting 41.5k across it.

Is there a code on the SMD R669?

[retiredcaps]

Re: Dell 2407WFPb Monitor - Bad Cap

My definition of shorted was 0 resistance.

I would say you are correct with the above statement. Components can also be shorted if they read say 5 ohms. Let's agree it is a "grey" area.

[sabretooth]

Re: Dell 2407WFPb Monitor - Bad Cap

I can't discern what's on R669. Most of the other SM resistors have legible writing on them but this doesn't appear to. I also notice that post #77 talks about a slightly different model of board, so perhaps it's just a difference between the two. Unless someone else can read their R669 or stick a multimeter on their good working L2K02, I suppose it's fair to assume that it's OK? It's not a guarantee, though.

[retiredcaps]

Re: Dell 2407WFPb Monitor - Bad Cap

I can't discern what's on R669.

Use a q-tip with some isopropyl alcohol to clean off the top and see if the writing under becomes legible?

[sabretooth]

Re: Dell 2407WFPb Monitor - Bad Cap

No luck, I'm afraid. A quick wipe with alcohol didn't improve it any. R669 is NE of the blown IC on the underside of the board, if you want to see what I see.

Hopefully someone else can measure theirs.

[selldoor]

Re: Dell 2407WFPb Monitor - Bad Cap

My best guess (Based on super pixel pic) would be that R669 is a 103 (upside down on the board)

[sabretooth]

Re: Dell 2407WFPb Monitor - Bad Cap

Higher-res picture attached. I think you're right! Looking at the attached picture, I guess physical damage is what's obscuring the reading, not dirt. Probably fair to conclude that this power supply is going be almost identical to that of post #77 and selldoor's guess.

I think I might as well go ahead and make the same replacements that #77 mentions regardless of test result, as well as our already-identified parts list.

Any guesses on what sort of wattage R670 would be?


By the way, thanks to everyone for their time regarding this.

[budm]

Re: Dell 2407WFPb Monitor - Bad Cap

If it is really 103 (10k) and it is burnt up as shown in the post 210 picture, I would think it is more likely to be either 1k or even 100 Ohms, the reason is that to burn up 10k resistor you will need very high voltage to force a lot of current to burnt up 10k resistor. If the max DC voltage in the power supply is 24vdc, with 10k resistor across 24v, the maximum power dissipation will be about 0.0576 Watt. If it is 1k, then it will be 0.576 Watt, then that will burn up this resistor. So how is this resistor connected in the circuits?

[selldoor]

Re: Dell 2407WFPb Monitor - Bad Cap

"Any guesses on what sort of wattage R670 would be?"

Depends on physical size Id guess 0.5w. however if you measure it
you can look it up on digikey 0.5w = (2.30mm x 6.50mm) approx

[budm]

Re: Dell 2407WFPb Monitor - Bad Cap

Yes, you can likely goes by the measured size to get close, 1/2w should be fine if it fits.
I would use the through hole resistor for testing. Do you know how this resistor is connected? is in the Inverter high voltage secondary side section?

[selldoor]

Re: Dell 2407WFPb Monitor - Bad Cap

I have just read post #77 and that R669 according to that is 1K so that would make the marking 102.
I believe the marking we are looking at could just as easily be 102 as against
103 - Also if you use a 1k and it blows it will cause less damage than a 1Ok
blowing.
I am unsure where the wattage query on R670 came from - it looks ok on the board - has it gone as well? or are you just replacing all as per #77.
I am further confused with budm's "Yes, you can likely goes by the measured size to get close, 1/2w should be fine if it fits.
I would use the through hole resistor for testing. Do you know how this resistor is connected? is in the Inverter high voltage secondary side section?"

@budm are you still thinking about the replacement for smd R669 as the O.5watt I suggested was in relation to R670 which IS a through the hole 2.2ohm redredgoldsilver

[budm]

Re: Dell 2407WFPb Monitor - Bad Cap

I am referring to that burnt resistor in post 210, R669 (1k). I also thought the Wattage question is also for this R669 resistor. Notes; I see now, the wattage is for R670, sorry for the confusion.

[sabretooth]

Re: Dell 2407WFPb Monitor - Bad Cap

Sorry, yes, two different resistors.

I've desoldered R670 from the board as it was hiding a scorch mark on its underside (it's in my casualty list). It was one of the larger pink resistors, identical to R615 (red red silver, 0.22ohm) and soldered about 10mm off of the board as opposed to the smaller resistors mounted flush. So with those differences I wasn't sure what sort of wattage it might be.

Newbie, feeling motivated to pull that monitor of yours apart yet?

[selldoor]

Re: Dell 2407WFPb Monitor - Bad Cap

Whoops - yes were all at it now - mixed silver and gold up, it is 0.22uf are you ok finding the wattage by size? Having looked at the picture again is there something odd
where the big cap is - I can see that a short lead cap has been used and soldered to old pins or connected in some way which is fine. What I cant see is that under that there is
a silver line of solder? what is that. Also by coincidence as I dont recall seeing one like this before but one cropped up yesterday, there is an orange 5a fuse at f701 , near the end of the big cap - have you checked that? ( I havent read all the thread)

[sabretooth]

Re: Dell 2407WFPb Monitor - Bad Cap

I checked F701. It seems OK! It's also not like any fuse I've ever seen before. But it checked out.

Unfortunately I've got no idea how to determine resistor wattage based on size. It's approx 4mm x 10mm, though. Googling "4x10mm resistor" has come up with a bunch of hits suggesting 1 watt.

The silver line of solder I think you're referring to - the goop that used to hold down the original capacitor? I'm not seeing any lines of solder. Also I'll be replacing that cap with one of an appropriate size when I get final confirmation of the parts list I don't think that the cap I have there is going to fit under the cover.

[newbie1]

Re: Dell 2407WFPb Monitor - Bad Cap

Newbie, feeling motivatet monitor of yours apart yet?

Sorry sabretooth. not feeling too good now. am typing this while lying on my bed now. in any case, if i am pulling it apart in a couple of days, what info or measurement do you need from my board?. sorry i did not fully read the latest replies from you guys.

[sabretooth]

Re: Dell 2407WFPb Monitor - Bad Cap

No worries newbie, rest up! I was just after a reading for R669 but I suspect that like the 2405's board in post #77 that it's a 1k.

Also, with R670, reading seems to indicate that you can substitute resistors of different power so long as the substitute is of higher power. Sound correct?