Dell N5010 inspiron short caps when plugged in

[kamel]

Platform: (wistron_berry_dg15_intel_discrete_uma)

Got dead Dell N5010 UMA for repair.

Replaced failing ISL62883HRT and shorted VCC_CORE and VGA_CORE outputting fets.

Now: When plugged in, light adapter immediately shuts off and PTC4702-PTC4703-PTC4706- PTC4707 (VCC_CORE outputting electrolytic caps ) short at once. Fixed 4 new caps, they short again.

What is likely to make the 4 electrolytic caps short and short again, knowing that ISL62883HRT was already replaced ??? Where To dig further?

[dj_ricoh]

Re: Dell N5010 inspiron short caps when plugged in

what diagram you're looking at?

[lorins_core]

Re: Dell N5010 inspiron short caps when plugged in

can you Upload the picture of mobo... i have some similar problem of my repair before.

[kamel]

Re: Dell N5010 inspiron short caps when plugged in

[QUOTE=dj_ricoh;591631]what diagram you're looking at?[/Q

As mentioned in my previous post, Dell under repair is UMA
Platform: (wistron_berry_dg15_intel_discrete_uma)

[kamel]

Re: Dell N5010 inspiron short caps when plugged in

can you Upload the picture of mobo... i have some similar problem of my repair before.

Will do either this evening or tomorrow morning.

[Levi]

Re: Dell N5010 inspiron short caps when plugged in

Check also the fets around the isl chip.They are very liked to have a short to ground.
Think about this, if power spike could kill the isl chip, its damn likely the fets around it could also be dead. But with a power supply, i think it is very easy to locate the short. So if u got a power supply inject 19v into the 19v rail and if any component heats up, then dat could be the culprit.

[kamel]

Re: Dell N5010 inspiron short caps when plugged in

can you Upload the picture of mobo... i have some similar problem of my repair before.

https://photos.google.com/photo/AF1Q...ZIcyIxb7DJR_e1

[kamel]

Re: Dell N5010 inspiron short caps when plugged in

Check also the fets around the isl chip.They are very liked to have a short to ground.
Think about this, if power spike could kill the isl chip, its damn likely the fets around it could also be dead. But with a power supply, i think it is very easy to locate the short. So if u got a power supply inject 19v into the 19v rail and if any component heats up, then dat could be the culprit.

Ok, checked PU4702, found it short again, though PU4702-4703-4704-4705-4707-4708 were already replaced. Removed PU4702 and measured Resistance to GND on PL4701, found 87 Ohms with CPU installed, very low!

Removed one leg of each coil i.e PL4701 PL4702 PL4703, found with GREAT SURPRISE over 0.180 kohms resistance to gnd before and after the coils;

Re-soldered coils, and measured again coils'resistance to GND found 0.220 kohms that's ok!

But couldn't understand why coils'resistance to gnd became normal, just after removal of one leg and resoldering it back ? I guess some discharge took place when legs were removed!

[khaahk]

Re: Dell N5010 inspiron short caps when plugged in

Why you think that 87 ohms is very low resistance on vcc_core with cpu installed. Seems normal or even a little bit high to me. If cpu removed then how much is resistance then?
What do you measure to define PU4702 short?

[gcomputers]

Re: Dell N5010 inspiron short caps when plugged in

Hi i just repaired one with this problem i find one caps shorted pc4507 on page 31.
removed it no short replaced ok , this caps you can find near battery connector.

[kamel]

Re: Dell N5010 inspiron short caps when plugged in

Why you think that 87 ohms is very low resistance on vcc_core with cpu installed. Seems normal or even a little bit high to me. If cpu removed then how much is resistance then?

Y're right I made a mistake please read "Removed PU4702 and measured Resistance to GND on PL4701, found 87 Ohms with CPU removed", very low!

What do you measure to define PU4702 short?

Try to explain : I measured Drain to Source (+PWR_SRC to PHASE1) and found 6 ohms, removed PU4702 and measured again, short is gone.Then checked PU4702 out of circuit it's confirmed shorted(5 ohms).

[kamel]

Re: Dell N5010 inspiron short caps when plugged in

Hi i just repaired one with this problem i find one caps shorted pc4507 on page 31.
removed it no short replaced ok , this caps you can find near battery connector.

PLease note that Platform is " wistron_berry_dg15_intel_discrete_uma" and not Wistron DJ2 Montevina UMA, 10240-SA (X00) though charging section and some other are same.

Do you confirm, that you got the same problem i.e :
When lap plugged in, light adapter immediately shuts off and VCC_CORE outputting electrolytic caps i.e PTC 4702, PTC4703.... short at once , and that issue was solved by changing shorted pc4507 ??? It's a little strange because pc4507 is in the charging section and PTC 4702... are in the VCC_CORE section. P.S confirm !

[khaahk]

Re: Dell N5010 inspiron short caps when plugged in

If VCCCORE was over limit, then cpu might also be dead. Install cpu and measure what resistance it shows. Try another cpu and check its resistance.

Try to power without cpu, does the fet go short again without cpu?
Maybe the cpu is shorted and the overcurrent kills fet, but the ISL62883 should prevent that from happening - so it is a strange situation...

[kamel]

Re: Dell N5010 inspiron short caps when plugged in

If VCCCORE was over limit, then cpu might also be dead. Install cpu and measure what resistance it shows. Try another cpu and check its resistance.

87 Ohms Resistance to GND on PL4701 with CPU removed, already confirms an existing problem, to solve.

Try to power without cpu, does the fet go short again without cpu?

Changed failing fet and shorted caps and powered without cpu, fan spinned for 30 seconds then stops and lap switched off !!! The 6 caps and fet PU4702 just replaced were found short again with PU4703!!!

Have to trace and figure out what is causing repetitive short to caps and fets before powering again. Off course, it's not CPU as it was removed.