NP700Z5C - Intermittent/No Power

My laptop (NP700Z5C) will no longer charge or show any sign that it is receiving power. At first I thought board failure but now I'm not so sure. The laptop will run fine on battery but it will not charge the battery or start anymore even when it's off. I cleaned up the DC jack and the main board the first time my laptop would not charge and it started working correctly right away. Later that night I unplugged it and then the next day it would not charge or acknowledge the laptop was plugged in so its sat there until the battery drained and shut off. At one point I was able to wiggle the jack and it charged for about 5 minutes then stopped again. This is why I don't believe it's a motherboard issue and maybe something similar to what is happening in this thread.

I tested the ac adapter and it was putting out 19.4 V at the jack. Then I tested the DC jack when the laptop was plugged in and it showed 19.4 V at the solders. The main battery connection shows 0.04 - 0.1 V depending on which connector is measured since there are about 8 or so.This seems low to me as I've seen other laptops around 1-3 V at the battery connector.

Maybe someone can chime in here and let me know if 0.1 V is normal?

The DC jack was soldered on at a shop a year ago as I had it replaced due to the plastic ring breaking. The solders still look fine and it seems to be working properly but I only think that because the voltage is getting though. I think at this point it's been established that the 90 W power supply isn't always good enough for this laptop. I'm going to try a 120 W later tonight and hope it comes back to life. My next step will be to replace the DC jack again and if that doesn't work I would assume a motherboard issue at that point.

If someone could give me some pointers on what to test with a multimeter that would be great. I'm not even sure if there is much left worth testing. The DC jack, adapter and battery connector seemed like the obvious places to start. Maybe 0.1 V is too low so the battery isn't even getting a charge. Hopefully someone reading this can tell me how I can for sure eliminate which components are working properly and which aren't. I'm not talking about all the little on-board components but more of the bigger obvious ones (DC jack/adapter/battery connection). I'll keep this post updated with anything that I try. Anyone's opinion on what could be wrong is also helpful. Thanks!

 

The battery has a label with a voltage and that value, or something close to it, should be measurable between the appropriate terminals (which two has to be determined by trial and error). If you can get the computer to work then run BatteryInfoView to see the battery health. If you are on the orignal battery then it could well be past its best. if it has does then the problem could be the battery not being able to charge even if the power is available.

John

 

Thanks for the reply John. Sorry for the long wait but I've been quite sick over the past few days.

I'm going to run BatteryInfoView to eliminate the battery tonight as per your suggestion. I managed to get the laptop charging again after I cleaned the DC jack with rubbing alcohol. This is how I was able to get it working last time too so my guess is that the DC jack needs to be replaced because the solders are failing. I'm kind of surprised by this because the DC jack looks fine and the solders appear to be in good condition.

I do find it odd that I was able to get proper voltage measurements from the DC jack even when it wasn't powering my laptop. I tried a 120W adapter as well and that didn't help bring it back to life. Once I eliminate the battery as the issue I will order a new DC jack and get it replaced.