Dell Inspiron 6000 works via battery but not charger

[fcda]

Hello, hoping someone can give me a few pointers to help troubleshoot this.

I was having issues with the original DC adapter and tried a universal one instead - unfortunately I got the polarity wrong. As a result the laptop works fine from a charged battery, but when using a genuine adapter (borrowed from friend with identical laptop) the adapter is not detected at all - no lights, no unknown adapter, no power, nothing.

So I removed the motherboard and had a poke around with a multi-meter. The socket seemed ok, but I resoldered it anyway. I found one capacitor near the socket which seemed to be shorted (probably C37, next to C36). I removed it and confirmed it was shorted. I had read of a fix for a Dell Latitude D505 which suggested just removing a shorted cap, so I thought I'd try it - nothing.

After a bit more poking I've realised that despite the labelling it's not a capacitor at all, but a 0 ohm "resistor". All others on the board marked with the 0 check out the same, plus it's black and the other caps are brown

So I'm back to square one. Any thoughts?

[Images attached of board front, back, front near socket and back near socket]

[b700029]

Re: Dell Inspiron 6000 works via battery but not charger

You will find the Schematic useful:
http://www.4shared.com/file/MPeB-dv3...mpal_LA-2.html

Power section starts on page 40.

[fcda]

Re: Dell Inspiron 6000 works via battery but not charger

Thanks!

Thought I'd found something. A diode, and 2 caps in parallel showing a short (PC52, PC51, PD18). For reasons I don't understand the schematic shows there is a link shorting these in the circuit.

Found a mosfet apparently shorted (PQ29), circuit shows a diode (PD29) in parallel and on the PCB... no diode both pads deliberately shorted. On closer inspection pin 4 isn't shorted to the others.

So, can't find any shorts in the "P" sections - caps seem okay and all mosfets and inductors.

I'll have to try it with the power supply connected. Not sure what to expect. Hopefully the schematic will be my guide.

[b700029]

Re: Dell Inspiron 6000 works via battery but not charger

You have to remove components from the circuit to test them properly.

I don't see what link you're talking about shorting them (page 43).

PQ29 is intended to control whether the DC_IN (from AC adapter) can be used to power the system, so that it's possible to run the laptop from battery even with the adapter plugged in. Maybe the designers thought that feature wasn't needed so they omitted it (pin 4 is the gate, that's why it isn't connected). This means the battery voltage should appear across the DC input while running on battery - you may want to check that.

[fcda]

Re: Dell Inspiron 6000 works via battery but not charger

You have to remove components from the circuit to test them properly.

I don't see what link you're talking about shorting them (page 43).

I removed all 3 and they were ok, but the short remained. Only then did I notice the link on page 43 - if you look left of the three components and PR59 there's a link going down to ground and on to pin 1 of the max1845 (if I'm reading it correctly). PC52, PC51 and PD18 also connect to ground.

PQ29 is intended to control whether the DC_IN (from AC adapter) can be used to power the system, so that it's possible to run the laptop from battery even with the adapter plugged in. Maybe the designers thought that feature wasn't needed so they omitted it (pin 4 is the gate, that's why it isn't connected). This means the battery voltage should appear across the DC input while running on battery - you may want to check that.

Ok, thanks.

[b700029]

Re: Dell Inspiron 6000 works via battery but not charger

You're right that PC52, PC51, and PD18 connect to ground, but not pin 1 of the max1845. That only connects to the first intersection after the inductor PL12.

Where are you measuring across that is shorted?

[fcda]

Re: Dell Inspiron 6000 works via battery but not charger

You're right that PC52, PC51, and PD18 connect to ground, but not pin 1 of the max1845. That only connects to the first intersection after the inductor PL12.

I thought pin 1 (OUT1) went to ground at the bottom of PQ9 before the intersection after PL12?

Where are you measuring across that is shorted?

I removed each component in turn and checked the component for a short and then the two pads from where it came. Each time the component was ok but the pads still shorting.

[b700029]

Re: Dell Inspiron 6000 works via battery but not charger

Should look like this.

That is a 1.05V rail that connects to the CPU and chipset, so it may look shorted. In fact, it is fine since you said the laptop works on battery. The max1845 regulates the PWR_SRC (either battery or AC input) down to 1.05V. The important thing is for there to be no short at the AC adapter input.

[fcda]

Re: Dell Inspiron 6000 works via battery but not charger

Almost 12 months to the day, and I'm back looking at this laptop. I now have a couple of other Inspiron 6000 boards to compare with (can't just substitute because the LCD isn't compatible).

I decided to measure some voltages around the power jack. Here's the an image from the schematic.



On the working board, the power supply supplies 19v to pins 2 & 3 of the connector. DCIN+ measures 19v. After PL2 I also get 19v - top of PC2, PR11 and pins 1, 2, and 3 of PQ3. PQ3 puts out 19v on pins 5, 6, 7 and 8. Pin 4 shows 7.7v. (PL3 is not populated on the board)

This is how it looks on the working PCB with the colours showing the different voltage lines:



On the faulty board the 19v drops to 7v right at pins 2 & 3 of the connector. So, I removed PQ3, PC2 and PL2 in turn, and only when I removed PL2 did the supply return to 19v (at this point the supply is effectively disconnected from the rest of the circuit). The two resistors PR11 and PR13 measure the correct values in circuit - they're tiny so can't easily be removed.

There was a little black mark under PL2 which might be a burn mark, but substituting with one from another board made no difference.

So, I thought I was in the right area with this but I'm stumped again. Any thoughts?

[carlo0014]

Re: Dell Inspiron 6000 works via battery but not charger

First of all are you than to check your dc adapter all most of laptop dc adapter 19v is the proper voltage so get your multimeter set to dc then insert the red probe at the center of the adapter that is + terminal then the black probe at the outside - terminal.. check if is it 19v then try to wiggle it and if still 19 v your dc adapter is in good condition.. if non then go to motherboard repairing .. good luck! tips when your laptop are non working any more do not suspect the critical damage the best is the basic check the laptop needs power to on right . check always the power supply!

[ben7]

Re: Dell Inspiron 6000 works via battery but not charger

What is the 'DOCK_DC_IN'? Does it go to the battery?

Remove parts PC2, PR11, and PQ3. Whats the resistance of the 'DOCK_DC_IN' to ground?

[fcda]

Re: Dell Inspiron 6000 works via battery but not charger

carlo0014, thanks but checking the power supply was the first thing I did, after my initial polarity mistake.

ben7, thanks. DOCK_DC_IN only appears on this part of the diagram. I assume it's for a docking connector, but there no sign of one on the board, not even pads.

I'm very reluctant to try to remove PR11 - it's tiny. It measures 150K in circuit which is correct. PR13 also appears okay, measuring 100K in circuit.

With PC2 and PQ3 removed (but PR11 still present) DOCK_DC_IN to ground is 250K which makes sense as it passes through PR11 and PR13 in series.

[siddiq]

Re: Dell Inspiron 6000 works via battery but not charger

Also check PC99 and PC102 .compare the resistance across the capacitors with the working motherboard and also check components around the charge IC [PU8] and also all capacitors around PQ3 [PC3 ,PC4,PC5,PC6].

[fcda]

Re: Dell Inspiron 6000 works via battery but not charger

Thanks siddiq. All the caps you mention measure 4.7K on both boards, but on the bad board it takes a few seconds to reach that value.

I checked around PU8 and found suspect resistances on a few components (bad vs good):
PC109 - 9 vs 18.58K
PC111 - 42 vs 18.5K
PR141 - 5.7K vs 9K
PR192 - 5.8K vs 12.12K

What sort of component is more likely to be affected by reverse polarity? I'm guessing resistors and capacitors (like these) will probably be okay? Most of them are really tiny and I'd rather not remove them unless absolutely necessary.

I'm wondering if it's more likely that PU8 itself has been damaged? It's a MAXIM 1535CE and the spec sheet says the input voltage is rated as 8 to 28v. I'd guess that it might not be too happy with -19v??

[siddiq]

Re: Dell Inspiron 6000 works via battery but not charger

Yes I think it is very possible PU8 is shorted since PIN1 is directly connected to +DC_IN.Remove PU8 from the motherboard and lets see if 19v 'flows' around.

[ravi_1617]

Re: Dell Inspiron 6000 works via battery but not charger

Hi
same problem no activity from adapter. works fine in charged battery. without battery no activity even adapter led is stable after plugging board

[ravi_1617]

Re: Dell Inspiron 6000 works via battery but not charger

what if I remove u23 (R5531V002-E2-FA_SSOP16 ) and start board

[ravi_1617]

Re: Dell Inspiron 6000 works via battery but not charger

Any match for MAX1535BE

[ravi_1617]

Re: Dell Inspiron 6000 works via battery but not charger

no one to reply

[razor_amd]

Re: Dell Inspiron 6000 works via battery but not charger

Check the mosfets on page 46. There is definitely a problem with charging circuit, because everything else works from battery.

Check PQ29 and PD29 first, than see PQ25 and PQ27.
Use analog multimeter, put the red onto ground and black onto PL19, let me know how much ohm did it measure.

When you connect power adapter to motherboard, check if there is heat coming from some component in charging circuit on page 46.