Solved! Why would dell computer not work with ac power

[Guest]

I was working on my dell inspiron when it suddenly went to battery power.It's plugged in and I have checked power to the outlet and to the ac adapter with a volt meter and everything seems fine there. I don't think the computer is recognizing the AC power coming in. Has anyone else experienced this problem ???

 

[RetiredChief]

NOTE: the Power pac output is normally DC, not AC.
I'm guessing you also measured the DC output, should be around 19VDC, with no load my be higher. The only way to rule out the adaptor is to:
(1) Best way - try a 2nd adaptor
(2) Measure the output of the adaptor with a Load on it. This is hard as you would need to connect it to a load resistor ( at least a 10 ohm restor rated at 40 WATTS - Ouch).
(3) Did your laptop come with a Cigarette car plug, you could try that. That would indicate that laptop circuitry is most likely good good.

In addition to the Power pack, the Laptop jack may be bad, or the Laptop input circuitry may be bad.

General info.
Battry is normally a Li-ion @ 10.9 Volts. The laptop input circity converts the 19 VDC form the power adaptor to +12 V to both charge the battery and operate the Laptop.

Editted - Had to change my "***" which was the English slang for Cigarette. which in the US is slang for a gay person. Built in checker does not know the difference!!!

 

[COLGeek]

If the AC adapter checks out, I would suspect the notebook/laptop power connector. If the power jack (connector) is defective, you will likely have to replace the mobo itself. Is your Dell under warranty? If so, contact Dell directly. Good luck!!!

 

[gdesilva]

NOTE: the Power pac output is normally DC, not AC.

In addition to the Power pack, the Laptop jack may be bad, or the Laptop input circuitry may be bad.

Is there an easy way to work out whether the problem is in the DC jack or in the input circuitry? In my case, AC adaptor does not work but the I can power up using a battery.

Thanks in advance.

 

[RetiredChief]

Once you have determined that the Power adaptor is GOOD.

You would need to dissasemble the laptop at least to the point of being able to see the ( get at the jack connections) jack and verify that the jack has not broken away from the circuit board. Remote posibility is a "cold" solder joint. Then it becomes a matter of tracing the Voltage with a DVM. Unless you are comfortable with this, it's time to either return to Dell, or take to a "good" repair shop.

 

[gdesilva]

Once you have determined that the Power adaptor is GOOD.

You would need to dissasemble the laptop at least to the point of being able to see the ( get at the jack connections) jack and verify that the jack has not broken away from the circuit board. Remote posibility is a "cold" solder joint. Then it becomes a matter of tracing the Voltage with a DVM. Unless you are comfortable with this, it's time to either return to Dell, or take to a "good" repair shop.

I have taken the mother board out but there are no obvious (as far as I can see but given my experience with PCBs this may not mean much!) problems with the DC jack or the soldering points.

My son who was using the laptop told me that he noticed some sort of an electrical short or power surge after which the power adaptor stopped working. I tested the power adaptor on another machine and it works fine. And as I mentioned earlier the laptop boots up with a battery without any problems.

Given that the laptop is unusable now I am tempted to have a go at replacing the DC jack but what I would like to know is that given the laptop boots with battery power, would it be safe to assume that problem is very likely to be with the DC jack?

Many thanks.

 

[COLGeek]

It is certainly possible that the DC jack is the problem, but I hope you are good with a soldering gun! You might check eBay or a Dell surplus vendor to get a replacement motherboard for your system since you have the old one out already. Regardless, good luck!!!

 

[gdesilva]

Thanks for the response COLGeek - I just needed a nudge to go ahead. The laptop is useless as it is anyway so there is nothing to loose. I have been making inquiries locally to find a person experienced in soldering as I tend to do 'sledgehammer jobs' when soldering.