Dell 2007WFP Won't Power On

[retiredcaps]

Re: Dell 2007WFP Won't Power On

Well every electrolytic cap on the main board except two are shorted to ground. Some of the ceramic caps in the NW quadrant of the board nearby the two regulators are also measuring shorted.

So either the main board is internally shorted at the board level or the big Genesis IC chip is shorted out.

Time to file this in the junk pile for now and move onto the next project.

[retiredcaps]

Re: Dell 2007WFP Won't Power On

FYI: Diagram.

I saw that when you initially posted it on the other thread, but no light bulb went off alerting me to the fact that the pinouts were different.

Sometimes the tongue has to get stuck to the lamp post before it sinks in!

[budm]

Re: Dell 2007WFP Won't Power On

FYI: Diagram.

[retiredcaps]

Re: Dell 2007WFP Won't Power On

5) For U5, this should work

http://search.digikey.com/us/en/prod...9-1-ND/1883984

It is a 2.5V 1A SOT-223 package.

@LAS I made a mistake on the digikey part number above. It was not obvious to me until I started measuring the voltage regulator out of circuit and I got weird results and then noticed the I G O markings. That is, pin 1 = VIN, pin 2 = GND, and pin 3 = VOUT.

The above digikey one that I referenced is one I'm used to recommending (1117), but the pinout is G O I (pin 1 = GND, pin 2 = VOUT, pin 3 = VIN). This is what I'm used to seeing 99% of the time.

As for the correct one, I will have to do some searching. Digikey's website doesn't search where I can input the pinouts.

[retiredcaps]

Re: Dell 2007WFP Won't Power On

IThe existing solder was the closest thing I've found to cement, and the parts just would not budge.

Before I went to sleep last night and before your update/post above, I took out the heat gun to desolder both voltage regulators. I have tried in the past to desolder these 252 and 223 packages without success so I switched to the heat gun (aka poor man's hot air rework station with no temperature control).

To protect everything around, I ordered 100 feet of Kapton tape ($4) and use it as a heat shield as you can see in the pictures. Both regulators came out with no problems after about 90 seconds of heat.

Now remember, my in circuit readings suggested both U13 and U5 were shorted. Well U13 and U5 are fine. There are no shorts and I tested it with a 9V battery and both output the correct voltage.

With both regulators removed, unfortunately, the pads still show a short. So there must be something else shorted on the logic board.

Anyway, I wanted to share a tip about using Kapton tape in the future whether you use a soldering iron or heat gun.

Note to self: Avoid this Dell model, even free, at all costs.

[Jasgriff]

Re: Dell 2007WFP Won't Power On

Cool!

I would never go back to working with one! keep us updated on the progress of your new project

[LAS]

Re: Dell 2007WFP Won't Power On

Hoping to acquire a flickering Samsung 22 inch.

A few months back, I was in possession of a flickering one, changed the caps, and took it to London with me as a present for a buddy of mine. I introduced him to the world of working with dual monitors and now he doesn't know he functioned all this time with just one.

[Jasgriff]

Re: Dell 2007WFP Won't Power On

Hey Las,

Your right there are some that might get the better of you but if you have only lifted a pad it wouldn't be the end of the world you can normally repair them.

If its gone already then i'm sure you can make up for it with your next project! as a matter of interest what do you have your eye on?

[LAS]

Re: Dell 2007WFP Won't Power On

Update on my project...I'm sorry to report that my logic card fix did not go well. The existing solder was the closest thing I've found to cement, and the parts just would not budge. I tried all the usual tricks - adding a little solder, adding a little flux, pressing the turbo button on my iron - and the board was damaged, and I screwed it up.

I started by removing the cap C155 next to the voltage regulators to make some more room. I ultimately got it out but it took one of the pads with it. And I've probably done fifty caps in the past year, and never had a problem.

Voltage regulator U5 went in cleanly, but the U13 was more difficult. And in the process, I damaged the microscopic C156 next to it. It just popped off, and it was so small I barely noticed it. And now either it's bad or put in badly - probably both but I could barely tell which side is up.

Anyway, they can't all be winners in this game and I already have my eye on another project for this weekend. But no doubt this one was a learning experience and the next one should go better. LAS.

[budm]

Re: Dell 2007WFP Won't Power On

I hope the MOSFET did not get damaged when the Diodes shorted out.

[retiredcaps]

Re: Dell 2007WFP Won't Power On

I would replace them with ONE Shottky Diode with 3 or 4A rating instead, I do not believe in using two Diode in parallel. Since there is a lot of space, you can try through hole Diode.

I found a SF34G through hole diode on a junk board and will try a single diode hopefully in the next few days (forecast is rain for next 3 days). I have backlog of stuff including the Toshiba 46 inch TV to work on.

[budm]

Re: Dell 2007WFP Won't Power On

I would replace them with ONE Shottky Diode with 3 or 4A rating instead, I do not believe in using two Diode in parallel. Since there is a lot of space, you can try through hole Diode. We already know that the original setup did not work.

[LAS]

Re: Dell 2007WFP Won't Power On

I have been thinking about how the discussion regarding these monitors is how the two Schottky diodes short out over time, possibly due to their relatively low 1a rating. Would anyone recommend replacement with 2a 40v diodes instead as shown in the link below?

http://search.digikey.com/scripts/Dk...3%2F61TGICT-ND

[retiredcaps]

Re: Dell 2007WFP Won't Power On

Budm's teardown ...

https://www.badcaps.net/forum/showthread.php?t=20531

[LAS]

Re: Dell 2007WFP Won't Power On

Looking forward!

[budm]

Re: Dell 2007WFP Won't Power On

OK, will do.

[retiredcaps]

Re: Dell 2007WFP Won't Power On

Anyone of you think I should start a new thread or not.

I think you should start a new thread with your pictures, analysis, diagram, etc and put a link back here.

That way, it is more of a budm case study.

[budm]

Re: Dell 2007WFP Won't Power On

I am not sure I should start a new thread for the Dell 2007 or not, I found 2 of them today at the recycle place and took it apart to check the voltages and draw up some diagram.
I have about 52 pictures.
Anyone of you think I should start a new thread or not.
Thanks.

[LAS]

Re: Dell 2007WFP Won't Power On

A good plan!! Thank you Retiredcaps for the parts lists!!

[retiredcaps]

Re: Dell 2007WFP Won't Power On

I currently have a Dell 2408WFP monitor that works - except it has a crack in the LCD panel. The circuit cards have all the replacement voltage regulators and Schottky diodes I need for this 2007WFP. Is it worth cannibalizing that, or should I concentrate on finding a replacement lcd for the 2408WFP?

1) I would leave the boards for the Dell 2408WFP alone.

2) The key is to interpret the voltage regulators as per my post #68

https://www.badcaps.net/forum/showpo...5&postcount=68

3) Both the 1.8V and 2.5V 1A regulator are widely available at digikey.

4) For U13, this looks suitable assuming the input voltage is less than 18V DC. As you know the power supply puts out 19V DC and I don't know if it is dropped down by the USB board before being fed into the logic board or not since I don't have a working system.

http://search.digikey.com/us/en/prod...ICT-ND/2095617

It is a 1.8V 1A TO-252-3 package.

5) For U5, this should work

http://search.digikey.com/us/en/prod...9-1-ND/1883984

It is a 2.5V 1A SOT-223 package.

6) For the diodes, I was looking at

http://search.digikey.com/us/en/prod...RCT-ND/2486749

A 40V 1A Schottky fast recovery diode in 0603 format.

7) Fuse.

http://search.digikey.com/us/en/prod...96-1-ND/615056

8) All the above are 50 to 65 cents each and I would highly recommend you get extras because if two people in different countries have the exact same components going bad, you can bet in the future that it will fail again for whatever reason.

9) So for about $3.00 in parts, this will hopefully fix the 2007WFP which is why I recommend not stealing parts from the 2408 as per #1.

10) Please doublecheck sizing for all parts.