Dell Inspiron M5030 intermittent short

[kschaffner]

Greetings, I should state that I have been a technician for 6 years now and have a good knowledge base for repair. Onto the issue! I have a Dell Inspiron M5030 laptop that has an odd intermittent short. Some history, last week the computer would not draw power from the ac adapter (ac adapter tests fine and tried others) but would power on and run just fine from battery. I disassembled the computer and busted out the multimeter. I traced the power from the dc jack all the way through the battery circuit and pretty much the entire board and everything checked out. I unplugged the ac adapter and hooked up the battery and traced it as well nothing seemed wrong. Upon plugging the AC adapter back into the unit it began to start charging and working as it should. I assumed (bad idea, I know ) that there was just a residual charge in a chip that I cleared with the multimeter. Now 1 week later it is doing the same thing. Traced the power and voila started charging again. There is a grey chip near the DC jack that I was getting the 19.58v on one side and not the other and the chips on the other side were getting the ~12v from the battery. Upon moving my multimeter to the other side of the chip I got a small spark and then the unit started to charge again. Do you think that this is my culprit? I have posted an image to show you where the chip in question is.

http://imgur.com/GHu0d

Thanks for your time!

 

[bryanl]

The device next to "PL4301" is not an IC but a discrete device, most likely an RF filter inductor and should have almost 0 ohms resistance. The fact you saw a spark and charging resumed when you measured the voltage indicates a solder joint was open. Applying rosin flux and a 20-30 watt iron may provide a permanent repair.

 

[sm625]

I dont think its an inductor since the other part labeled B14A is a diode. Which means the +supply is running through the other foil (thru B14A), and the unlabeled part is going from + to common. It must be a cap or more likely a TVS. Placing the meter on it should have no effect on the circuit what so ever. Assuming your meter is set to volts. It must be board flex that actually caused the effect you describe.

 

[kschaffner]

It wasn't board flex due to me not touching the board anywhere other than with the voltmeter and I didn't put enough pressure on it to cause flex, I touched the side of the part not the top or the point at which it solders to the board.

 

[sm625]

ok if you touched the side and it made it work then it could be cracked and shorting. In which case touching it may cause it to open and behave normally. I am about 90% sure that if you carefully break off that part, your charging circuit will function normally. To be clear, I am talking about breaking off this guy:

I am not 100% sure though. However, I am 100% sure that if you break the part off, you wont damage it any worse than it already is lol.

 

[bryanl]

I dont think its an inductor since the other part labeled B14A is a diode. Which means the +supply is running through the other foil (thru B14A), and the unlabeled part is going from + to common. It must be a cap or more likely a TVS. Placing the meter on it should have no effect on the circuit what so ever. Assuming your meter is set to volts. It must be board flex that actually caused the effect you describe.

I agree B14A is a diode, but the +supply doesn't normally run through it since its anode is grounded to the foil with the large hole in the corner, the same foil where the 19V power connector's ground pins are soldered, while the cathode connects to one end of PL4301, whose other end goes to the foil where the power connector's +supply pins are soldered. I believe the connections are similar to those for FL1 (for PL4301) and RV2 (B14A):

I also agree about the board flex, which likely cracked a solder connection, but I would not "break off" component PL4301, as opposed to carefully unsolder it (I assume that's what you meant), but I would rather first try reflowing the solder joints of PL4301 since I believe that will restore the power connection, unless PL4301 itself is cracked.

kschaffner: What was wrong with the computer to require a previous repair evidenced by leftover flux on some pins of the 4407A MOSFETs and the power connector? Also that connector has cracked solder on 2 of its +supply pins, perhaps from mechanical stress that occurred after that repair.

 

[kschaffner]

This board has never been repaired, but this model is know to run hot and is probably the cause of the yellowing on the solder points. The jack is also original and has never been removed. I have 2 of these laptops and they both run very hot like 50c idle even after I replaced the TIM with AS5. I'm also guessing that since I was able to get 10v from the BA022G component and was only getting the 19.58 on one side of PL4301 that PL4301 has to be the issue with this laptop.

It's weird that after volt testing that part and it begins to work it will work for days and then crap out.

edit: I will let you guys know my results when I replace that part.

 

[sm625]

If ground is the foil around the edge of the board, then that gray unlabeled part has to be an inductor. So it cant be opened, it has to be shorted. You have to place a short across it. Maybe it is cracked open, and touching it caused it to close.

 

[bryanl]

This board has never been repaired, but this model is know to run hot and is probably the cause of the yellowing on the solder points. The jack is also original and has never been removed. I have 2 of these laptops and they both run very hot like 50c idle even after I replaced the TIM with AS5. I'm also guessing that since I was able to get 10v from the BA022G component and was only getting the 19.58 on one side of PL4301 that PL4301 has to be the issue with this laptop.

Which pins of the BA022G (actually 4407A; BA022G is likely the date code)? Pins 1-3, for the source terminal, all connect directly to one end of PL4301, and both ends of the latter should measure identically, or about 19.58V., unless it's cracked or has a cracked solder joint. Resolder both ends, but if that doesn't help, then temporarily solder a jumper across it.

4407A BA022G (D=drain, S=source, G=gate):

That board had been repaired, perhaps at the factory during rework, since flux is never left on small, machine soldered components otherwise.

The power jack didn't have to be removed to have been resoldered, as the flux proves it had been, and I suggest resoldering at least those 2 pins with the cracked solder around them, as a preventative measure.

 

[iKonTechDevelop]

PL4301 is your problem you get it to come on by adjacently hitting PL4301 and jumping it to the little guy to the left of it that makes it work as a bridge. However the main problem my board has is i can actually move PL4301 with a little pressure bad joint flux and rework and bingo 30 dollar laptop i bought is fixed! Re-flow/Rework DC Jack to.

Thought i would let ya know in case you have not gotten it just apply pressure to PL4301 and it will light up! Does for me any how.

Have a good one this helped me a bit in my search for an answer so i thought i would leave my fix for you!

 

[BarneyBear69]

Hi, I have the same model laptop to be repaired. The brief outline of the problem is that my son sat himself down on the laptop resulting in a broken screen. I was informed by my son that the power adaptor was plugged in at the time. It was subsequently discovered that the power adaptor had developed a fault (low output voltage 14v).With a replacement power adaptor, the laptop still shows no sign of life(no LED's lighting up etc).A number of voltage checks were performed around the DC input jack, but without a circuit diagram it is difficult to trace. Fusible devices on mobo appear ok, but I suspect some safety / protection device has gone O/C. Flexing the mobo has no effect, nosigns of cracks. There appears to be no continuity to earth from the -ve terminal. (Is Centre pin +ve?). Any advice or tips are appreciated!

 

[iamalanwelch]

I am having a problem with the bigger brownish colored one. It is the second if you go left from the one sm625 has circled in black on his/her post from 05-21-2012 01:54 PM. It has a crack in it.
My questions:

1. What is it?
2. Can I go purchase one from radioshack?
or
3. Can I purchase what I need from radioshack and build a work around for it?

I know that I can do the work. I just need to know, what I'm dealing with to get a replacement/equivilant.

Thanks,
Alan

 

[iamalanwelch]

Is there anyone still there to help me out with this problem?

 

[William Gaatjes]

I am having a problem with the bigger brownish colored one. It is the second if you go left from the one sm625 has circled in black on his/her post from 05-21-2012 01:54 PM. It has a crack in it.
My questions:

1. What is it?
2. Can I go purchase one from radioshack?
or
3. Can I purchase what I need from radioshack and build a work around for it?

I know that I can do the work. I just need to know, what I'm dealing with to get a replacement/equivilant.

Thanks,
Alan

It seems very much to be a ceramic capacitor.
Value is difficult to determine when it is cracked. However, when cracked, you will be able to solder it loose from th pcb. When it has ohmic resistance (use your multimeter in the Ohm range (resistance measurement.)), you will know it is defect for capacitor do not have a resistance (A current only flows when the capacitor is charged or discharged).

To give you some idea, see this website but also search highly technical for ceramic capacitors with the search option of the forum :

http://www.johansondielectrics.com/...aining/basics-of-ceramic-chip-capacitors.html

Cracked ceramic capacitors :

http://www.ami.ac.uk/courses/topics/0179_fmcc/index.html

EDIT :

I should note that the ferrite bead (PL4301) from the previous post can easily burn and break apart because of a cracked ceramic capacitor behind it when looking from the power source.

 

[William Gaatjes]

When the corner of the pcb can bend easily even when inside the housing, any large ceramic capacitor on that part of the pcb will crack over time and cause intermittent failure.
It will work for a few days and then stop working or cause system crashes and start working again depending on humidity or temperature or mechanical vibration.

 

[superpig]

Hi everyone i just recently came across a laptop with the same problem after taking out the mother board i discovered that the pl4301 diode had black all around it and it was slightly melted. I managed to get a resistance out of it still however i broke the solder from the other side now.

Is the diode still usable if i just solder both ends back onto the board? also does anyone have any tips im still new at soldering and find it hard to get the solder to actually go where i want it to.

 

[William Gaatjes]

Hi everyone i just recently came across a laptop with the same problem after taking out the mother board i discovered that the pl4301 diode had black all around it and it was slightly melted. I managed to get a resistance out of it still however i broke the solder from the other side now.

Is the diode still usable if i just solder both ends back onto the board? also does anyone have any tips im still new at soldering and find it hard to get the solder to actually go where i want it to.

It is not a diode.
It is a ferrite bead.

Similar as can be found here :

http://katalog.we-online.de/en/pbs/WE-MPSB?sid=91b95db853

You can just short it. But with what you described, there is probably more defective. Thus i would not advise you to short it until you measured the board if any short circuits exist or that faulty components are present.

 

[superpig]

Ops it seems like i miss read something thank you! now next question if its not to much trouble could you try and explain what you mean when you say "short it" and how exactly would i test the board for short so far i was able to get a reading of 19.5V from the dc jack which means thats fully functional right? If you look at this picture youll see what i tested and got for voltages. Thank you in advance! also the ferrite bead is complete removed now.

 

[William Gaatjes]

It is difficult. Just as i mentioned that it is common that on pcb that can bend ceramic capacitors can crack, the same fault mechanism applies for ferrite emi suppressor beads. Ferrite beads are brittle, just as ceramic capacitors. When you write that the solderjoints of the dc plug have come loose, i can certainly imagine that a considerable amount of mechanical stress must have been applied to the pcb every time the dc power plug has been connected, possibly bending and warping the pcb and therefore PL4301 could have cracked because of this. Best thing is to take your multi meter and do some resistance measurements over the cpu powersupply and all other smps that you can find. What is also handy, is to measure the resistance of the smps mosfets and to look if these are burned or damaged.

Easiest way is to take the multimeter in resistance measurement and measure the resistance over all ceramic capacitors on the pcb that seem to be used as power supply decoupling. If none read as 0 Ω, you can connect a small 1 Ohm resistor instead of PL4301 and hope nothing will burn out.
Another options is this: suppose the external SMPS PSU from the laptop can deliver for example 3 amps. Take a glass fuse of 3.15AT(slow) with a fuse holder and some leads, connect it at the place of PL4301.

and

or

If the fuse blows immediately , you have a short. If the fuse goes after 30 seconds or so, the laptop will probably function and you can replace PL4301 for a fuse with a higher value. Then measure all power supply rails if within specification.

See the library thread for general information :

http://forums.anandtech.com/showthread.php?t=2250963&highlight=library

 

[superpig]

thanks for putting so much effort in your responses just a couple more questions i swear ^^ ok so first when you say replace with a 1 ohm and hope nothing burns does that mean i could cause anything to blow(would hate to give this laptop back to the person and it blows up in there face ) and for the fuse lets say it doesn't burn out do i actually place and solder the fuse to the board?

 

[William Gaatjes]

thanks for putting so much effort in your responses just a couple more questions i swear ^^ ok so first when you say replace with a 1 ohm and hope nothing burns does that mean i could cause anything to blow(would hate to give this laptop back to the person and it blows up in there face ) and for the fuse lets say it doesn't burn out do i actually place and solder the fuse to the board?

No, the fuse and the 1 Ohm is part of your test equipment. It ensures that while you do preliminary testing, nothing burns out beyond repair. After preliminary testing and having measured voltages and checked that no components get hot anymore(temperature checking), solder in a new emi bead and do thorough testing again. Also do some 24 hour burn in test after complete assembling the laptop together. Let the cpu calculate some pi test and after that, do some ram memory tests and gfx tests to test the durability while connected on the external SMPS power supply. This will tax the laptop and all the circuits. If the laptop keeps working during that burn in test, you can assume it will continue to work. Then you can start testing the peripherals and give it an

.

 

[superpig]

GOOD NEWS! I tested the motherboard with a fuse and it turned on with only the PS. Other then testing to make sure it actually charges the battery now i should be good to solder the beads. I will update and let you know how this all turns out thanks for your replys.

 

[mindless1]

nm

 

[superpig]

Hi everyone just letting you know that it worked i just soldered it last night and it started right up it even charges the battery now. Took me forever to find the exact beads and ended up having to call a company that works with this Germany company so took 3 weeks to ship but all in all cost 30$ for 25 beads (yay replacements) much better then buying a brand new laptop thanks for the help couldn't of done it with out you.

 

[mnemonic76]

Hey guys, just wanted to thank you for saving me a lot of heartache and troubleshooting. Turns out on my m5030 motherboard the PL4301 had bad solder joints.. came right up with very little force. Resoldered and voila! all is well.

Thanks for contributing your time, effort and expertise to an online community of total strangers. This is truly the best of the Internet.

mnemonic76