pc dell latitude d600 no powers

[djad62]

hi everyone
when I plug the charger on the motherboard connector of my pc dell latitude d600 the blue led of the charger goes off I guess it's a short circuit but I can't find the short circuited component I ask for help please thanks
I disassembled the laptop I tried to go everywhere to test some components, the problem is that I'm just a beginner and I'm still learning I can't target the wrong component, I found a lot of capacitors that beep on both sides and to remove them and test them it's a lot,
I have pictures of the beast and the schematics too (the computer is old and I'm trying to fix it just for my learning and experience).
thank you for your help

 

[73's de Edd]

Sir djad62 . . . . .


With your / that provided info, looks like you might need to check out the left half of the schema in order to see if your power supply is getting 3-3.3VDC to the VIOLET flagged test points and then the mid schemas RED flagged 5VDC test points.
Then there is yet the last supply as the 2 GREEN Flagged power test point SouRCe 's and its incoming E-caps tell us that the voltage is going to be somewhat below their ratings of 25VDC.
Now, since the batt pack for one of those systems is being three series arranged sets of two paralleled Li Ion cells . . . . yielding ~ 11-12VDC . . . seems like that would be, the voltage that is to be expected.
That full supply level is then being utilized by the two . . . . PQ4-PQ5 /PQ6-PQ7 and PQ8-PQ9 /PQ10-PQ11 FET sets, with their associated PL1-PL-2 ringing inductors to DC downconvert, for creating the, somewhere between the digitally adjustable 1.34 through 0.940 Vcore supply, which you would monitor at the BLUE flagged VHCORE test points.
Report your voltage level findings.

Your, now color coded / and / marked up SCHEMA . . . . .







73's de Edd . . . . .


A lot of people have heard opportunity knocking at the door, but by the time they finally unlatched the chain, pushed back the dead bolt, turned two locks, and shut off the burglar alarm, it was gone.



.

 

[djad62]

Thank you sir 73's of Edd for the return.
to measure these voltages I need to be able to connect the laptop's charger to the motherboard but the problem is that when I plug it in nothing happens, there is no current coming in from the connector.

 

[73's de Edd]

Is the batt pack installed in the unit and being up to enough of a charged state so as to give some LED indication, on attemting to run off battery power alone.
As most of the heavy demand run power is from the battery and the charger just maintains a "keep up " /charging.
And is the charger the original unit that worked in the past ?

Check the number of pins / connections related to your power units end plug and see if the info below is possibly being relevant to your unit.

FIO . . . .
http://www.laptop-junction.com/toast/content/dell-battery-charging-system-d5xx-and-d6xx-laptops
http://www.laptop-junction.com/toas...10-battery-connector-pinout-and-signal-timing

 

[djad62]

I try to charge the battery with a laboratory power supply but it doesn't charge the current is 0.003 A with a voltage of 11.7 v, and when I inject 15v at the terminals of the motherboard connector everything is off I guess there is a short circuit on the motherboard but I don't know how to target the wrong component(s), I'm a beginner and I'm trying to learn and moreover I don't speak much english fortunately there is the translator, and thanks for your help

 

[kenny256]

i have a similar situation and found that the 3.3V buss was shorted to the ground plane thru several big FETs, 8-pin devices such as the PQ2 PQ3 on your schematic. Very difficult to remove and replace just for troubleshooting to determine what else may be damaged. Not a good first project for learning about repairs so don't feel bad about walking away from this one.

 

[djad62]

hi kenny256
I have a hot air station for desoldering PQ2 and PQ3, and I would like to know if I desolder them I can test the motherboard without the FETs ?

 

[kenny256]

Well you are better equipped than the average person. The only test i know would be to determine if the power and ground planes were no longer shorted, e.g. where the capacitors were measuring shorted due to fail-shorted FETs.

 

[djad62]

Could you please explain to me how do I proceed?

 

[djad62]

I don't have to find the FETs PQ1 and PQ2 on the motherboard

 

[kenny256]

Where were you measuring a short between power and ground--was it on the 3.3V buss? Find which buss is shorted on the board and then compare it to the schematic to find which section is affected.

In my case it was the 3.3V buss. If true for you, then you would want to check for the resistance/continuity of the FETs now on the board, between the Drain and the Source. If you measure a short circuit condition (very low to no resistance), then remove the FETs and check them on the bench, or on a curve tracer if you have access to one. Also check whether the previously measured shorted capacitor readings still occur or now read normal. If your issue is in another section of the board/schematic, then you must analyze the schematic to look for potential culprits, then remove them from the board to test and replace. You can't apply power to the board until you find the culprit of the shorted circuit.

 

[kenny256]

Are the Reference Designators marked on the board? i can't see anything in your pictures--you need to take closer view high res picture in order to read the RDs and part numbers, etc.

 

[djad62]

hi kenny256
What is the number of the PQ1? PQ2 and PQ3 is :
"RHU002N06"
but they don't have 8 pins, only 3 pins.
I attach a photo of these parties, I do not know if it is of good quality.

https://drive.google.com/file/d/1LxLhrvMAHO0oS2zLHeFWEawVdEKB6_nb/view?usp=sharing

 

[kenny256]

That's a better picture, we can see that the board is marked with the Reference Designators.

Which capacitor(s) did you measure that showed as "short circuit"?

Find PQ4-PQ11 and see if those are shorted between the Source and Drain.

Can you get a picture with good resolution and clear detail of the board that includes most of the parts in the schematic?

 

[djad62]

Hello,
I made some measurements on the motherboard without extracting the components with the multimeter in diode position and here are the results:
PQ4 : there is no mosfet
PQ5: black tip on drain and red tip on source
(038)
black tip on drain and red tip on grid
( no value )
red tip on drain and black tip on source
(043)
red tip on drain and black tip on grid
(530)
PQ6: black tip on drain and red tip on source
(beep)
black tip on drain and red tip on grid
( 1057 )
red tip on drain and black tip on source
(beep)
red tip on drain and black tip on grid
(450)
PQ7: black tip on drain and red tip on source
(beep)
black tip on drain and red tip on grid
( 1057 )
red tip on drain and black tip on source
(beep)
red tip on drain and black tip on grid
(450)
PQ8: black tip on drain and red tip on source
(038)
black tip on drain and red tip on grid
( no value )
red tip on drain and black tip on source
(043)
red tip on drain and black tip on grid
(530)
PQ9: no mosfet
PQ10: black tip on drain and red tip on source
(beep)
black tip on drain and red tip on grid
( 1055 )
red tip on drain and black tip on source
(beep)
red tip on drain and black tip on grid
(450)
PQ11: black tip on drain and red tip on source
(beep)
black tip on drain and red tip on grid
( 1055 )
red tip on drain and black tip on source
(beep)
red tip on drain and black tip on grid
(450)
PL1: (beep) on both sides
PL2: (beep) on both sides
PC11 : (beep) on both sides
PC31: (beep) on both sides
PD2: (beep) on both sides
PD4: (beep) on both sides
in the other side all the components that I have circled in red on the motherboard there is a (beep) on both sides, I guess there is a short circuit somewhere
attached pictures
if you want more informatione please do not hesitate to contact me

https://drive.google.com/file/d/1hS-Y2zoUKPg1Y8R9uboVvXfi5nTWHjjk/view?usp=sharing

https://drive.google.com/file/d/1HZ7NTNTtrBxrzN6IJmbvRzH65i3tdom3/view?usp=sharing

 

[kenny256]

Do you have another page of the schematic showing which devices connect to the VHCORE voltage buss? It may be one of the load elements that is shorting it.

The measurements are showing that indeed the buss is shorted but it's hard to believe ALL the FETs in two different branches blew, plus all the capacitors.

Maybe you could remove the big sense resistors to isolate the supply from the load and check on which side the shorting is still present, i.e. remove PR7 and PR25, the 2mΩ resistors, then diode check across PD2,3,4, and continuity check across capacitor PC12,27

 

[djad62]

I attach other diagram

https://drive.google.com/file/d/1S5OYp0sx7E1Mge3WCZy0bvFJ2SwzTyHB/view?usp=sharing
https://drive.google.com/file/d/1j0Lf4yNlOmZP4FsH_QVwNrL83l_Sxzu2/view?usp=sharing
https://drive.google.com/file/d/1GzvcUScP5vox1x9KN5Wp4z_wPdR-DKEb/view?usp=sharing
https://drive.google.com/file/d/1lMqjUaOS27zYky2AgFav_TYVZ6kFA3Ox/view?usp=sharing

 

[djad62]

I removed the two resistors PR7 and PR25 and I see that there is no short circuit on L1, L2, PD2, PD4, PC11 and PC31 but on the other side there is still a short circuit on PC12, PC27, PD3 and the other small capacitors.
when I measure the resistors I removed it gives me a null value

 

[kenny256]

So the problem is on the Load side. The removed resistors have a value of 0.002 , which i doubt your meter could measure accurately (would show as zero like a dead short).

 

[kenny256]

On the schematic that Ed shows in post #2 there is a blue box around "VHCORE", which likely opens to another page of schematics related to that voltage. That is what is needed, i could not find any reference to that designation on any of the pages for which you gave links in post 17.