Dell 2407WFPb Monitor - Bad Cap

[elvena]

Re: Dell 2407WFPb Monitor - Bad Cap

Good work! First really successful repair of this model monitor that I have seen. Also, to save members from looking, can you please supply the values of the resistors you replaced? Thanks!

Thanks!

R669 is 102 (1000 ohm)
R670 is 0.22 ohm

[Fhajad]

Re: Dell 2407WFPb Monitor - Bad Cap

So I'm trying to fix up a power board from a monitor at work.

http://i.imgur.com/QIQWh.jpg
http://i.imgur.com/J4RdP.jpg

Replaced the large cap, seems the R670 is bad as well. Anyone else notice anything? I can probably grab the R670 at radioshack on my lunch. Gonna find my multimeter as well to check anything else if people have recommendations.

[selldoor]

Re: Dell 2407WFPb Monitor - Bad Cap

I recommend you post the pictures as follows
Welcome to the forum-
We can help a lot more if you please post good clear pictures of the whole chassis, and then pictures of each board, front and back and close up of connectors, (max resolution 2000x2000 and 2MB) using the manage attachments button, which is found by clicking "go advanced" under quick reply.

Please do not post inline and offsite as they slow down the loading of pages.

Examples of what is needed
https://www.badcaps.net/forum/attach...1&d=1290283049

https://www.badcaps.net/forum/attach...7&d=1280167246

It will be useful if you can say what the supposed fault was and a bit about yourself - skills tools etc.

Tell me what you see here:

[Fhajad]

Re: Dell 2407WFPb Monitor - Bad Cap

Hopefully these are a lot better.

And my skills are amateur really. I have a radioshack iron and a few things here and there (multimeter and such). Will eventually will invest on a better set of tools. Hoping this is one of the easier boards to repair but doesn't seem like good odds.

[Fhajad]

Re: Dell 2407WFPb Monitor - Bad Cap

Also sorry for glares from overhead lights, it's overcast/raining outside and this is the best lighting I have.

[jetadm123]

Re: Dell 2407WFPb Monitor - Bad Cap

Hopefully these are a lot better.

And my skills are amateur really. I have a radioshack iron and a few things here and there (multimeter and such). Will eventually will invest on a better set of tools. Hoping this is one of the easier boards to repair but doesn't seem like good odds.

Actually, from what I've seen the success rate for repairing this board has been poor. One of the successful repairs was back on post #258. You can check your parts against what elvena replaced.

Also, it wouldn't hurt if you gave a description of the symptoms your monitor is having.

[selldoor]

Re: Dell 2407WFPb Monitor - Bad Cap

Pictures are not a lot better - too grainy - more natural light is the key.
Anyway - you still need to tell us the problem. What happens when you plug it in. What happens when you switch it on. What does the panel (Screen) do
what does the power led do. Any noises ( Hiss squeeks etc)

As you will have read we only know of one of these being fixed by conventional methods - others have modded with an external power supply.

[Fhajad]

Re: Dell 2407WFPb Monitor - Bad Cap

Natural light is unfortunately impossible today.

And no noises, I just connect AC and it does nothing. No lights, logo, pops, nothing. The power button makes a nice normal click.

[budm]

Re: Dell 2407WFPb Monitor - Bad Cap

When the Source resistor is damaged, it means that the MOSFET has shorted out and it will take out the IC that drives the MOSFET also, you should replace them at the same time.
2407 tear down:
http://s807.photobucket.com/albums/y...ll%202407WFPB/

[selldoor]

Re: Dell 2407WFPb Monitor - Bad Cap

Ok plugged in but not switched on what voltage across the Big Cap?
Meter on 600VDC red prob on positive leg of cap and black probe on negative leg.
Then do it again after you press the power switch. CARE High voltages do not touch any heatsinks or other parts.

If its been switched on switch off & leave 5 mins then
I cant see that you have checked the main fuse? or the Black round component next to it.
For both meter on ohms 200 and check resistance - post results

[Fhajad]

Re: Dell 2407WFPb Monitor - Bad Cap

00.6 on the fuse, 07.1 on round component.

My multimeter only goes up to 500VDC and it reads 158.

I am also reading through for the components required for the IC, MOSFET, and resistor. I see the resistor is a .22ohm as mentioned above.

[Fhajad]

Re: Dell 2407WFPb Monitor - Bad Cap

So would it be a safe bet to replace most of the items listed on the previous page from the guy that did everything successful, or just replace the 3 mentioned and call it good? Is there a chance of the 3 I replace getting shorted out again if something else down the line is bad?

I'm thinking of stopping by Fry's in the next two days to pick up pieces. Surface mounted stuff does give me the willies since I don't have a reflow station, but I do have a regular ol' huge heat gun I can use.

[budm]

Re: Dell 2407WFPb Monitor - Bad Cap

So what do you get when you check the MOSFET, is it shorted? Does the 0.22 Ohms resistor check open?

[Fhajad]

Re: Dell 2407WFPb Monitor - Bad Cap

I haven't checked the MOSFET but the .22ohm resistor has two cracks down the sides on the top so I'm pretty sure it's blown.

https://www.badcaps.net/forum/attach...3&d=1344971275

You can see the crack in this picture.

[budm]

Re: Dell 2407WFPb Monitor - Bad Cap

OK, it would be safe to replace the IC's, MOSFET's, resistors, main filter cap components in the post 258. The surface mounted may not be damaged but look at them real close with magnifying glass.

[Fhajad]

Re: Dell 2407WFPb Monitor - Bad Cap

When looking at the surface mount, am I just checking for discoloration on the solder joints primarily?

So list I have to replace is at least Q651, F601, and R670. I'll try to grab the others when I get in tomorrow and take an extra look at everything. Hopefully I can traditional repair this board no problem. I'm just feeling sketchy about using the bypass method in a work environment.

[budm]

Re: Dell 2407WFPb Monitor - Bad Cap

The surface mounted resistor, when it burns up you will see the middle section has a small black hole, pit, bulging, the printed number on the body will be damaged also.

[Fhajad]

Re: Dell 2407WFPb Monitor - Bad Cap

Thanks for the quick answers, I greatly appreciate it and everything you guys do to help people like myself out. I'll report back tomorrow with anything else if needed.

Thanks again everyone.

[budm]

Re: Dell 2407WFPb Monitor - Bad Cap

One place that you may be able to get broken electronics is the Electronics recycle in your area, I myself do volunteer works every Saturday, you get to work on all kind of stuff and get great deals on boards and parts. My local place is WWW.CRC.ORG, I have been at the place since 1995.

[jetadm123]

Re: Dell 2407WFPb Monitor - Bad Cap

One place that you may be able to get broken electronics is the Electronics recycle in your area, I myself do volunteer works every Saturday, you get to work on all kind of stuff and get great deals on boards and parts. My local place is WWW.CRC.ORG, I have been at the place since 1995.

I remember going to CRC.ORG on Saturdays. Got some good deals. They get some good stuff from local companies in the Silicon Valley. Unfortunately, because of the cost of gas, it's no longer economical for me to drive out there.