### Network

#### Dang8701

Aug 20, 2014
10
I am currrently trying to solve a no charge problem on my samsung np-n 310 netbook. I am almost sure it is the cable.

So i took out the 50 year old voltometer and lo and behold, the current is flickering at around 20 volts where it should be.

But the issue i think is the flicker, the needle keeps pulsing in a heartbeat rythm from 20-23 or so every two seconds or so.

THEN I switch the meter to read AC just for the hell of it and it reads just a few volts lower, but in AC!!!

so my theory is that the power brick is bad and allowing 20 volts through at all times, more or less, somewhat failing to keep the voltage steady and somehow producing AC at the same time and due to all these irregularities my computer battery not allowing itself to charge???

Anyone have an opinion???

This would be really good news for me by the way. A new brick is 3 dollars + shipping

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
12,613
At 3$there's almost no risk in trying a new charger, although at 3$ you also cannot expect a quality charger. Once youve verified the old charger is defect, I recommend you get a quality charger (which will have a much higher price tag) to protect your laptop and yourself from any electrical hazard and/or shock.

#### Gryd3

Jun 25, 2014
4,098
Current is measured in amps, and not volts. Be careful with this designation.

What is the brick rated for?
There are numerous ways for it to fail, and for it to operate...

Can you take it to a futureshop or radioshack outlet and have them try a universal brick on it?

#### Dang8701

Aug 20, 2014
10
will do, thanks...and the meter is actually pretty awesome, its super accurate and something to be said for the straightforwardness of analog with this kind of stuff

#### BobK

Jan 5, 2010
7,682
Given that you have a 50 year old voltmeter, I would not trust it's readings. It is possible the AC input has no capacitor (or a shorted one) to block DC and that is why you get a reading on AC.

With the adapter reading near the correct voltage, I would suspect the battery.

Bob

#### Dang8701

Aug 20, 2014
10
@BobK
thanks for the tip. I might check on that in the meter.

But as I am trying to highlight, there is this flicker in the output of the cable. I test it from the first joint of the cable before it gets to the brick, and no flicker at around 120 volts
but then at the output there is htis heartbeat flicker that resembles the green power light's flicker exactly when its plugged in with the batter takien out. thats what makes me think its the brick

#### KrisBlueNZ

##### Sadly passed away in 2015
Nov 28, 2011
8,393
Hey, I like the meter! There's nothing wrong with them for most uses. When I was doing consumer repairs I used an analogue meter in preference to a digital meter most of the time. I still have a very nice old Hioki analogue meter.

Just like Bob said. Don't worry that the meter indicated voltage on the AC range. It probably doesn't have a DC blocking capacitor and that's probably normal. If in doubt, set it to an AC voltage range and connect it to a 9V PP3-type battery, to see whether it gives a reading on that too.

I don't understand what you mean by "flicker in the output of the cable". Are you able to measure the output voltage from the power supply with the plug plugged into the laptop? It should remain at 19V, obviously. It might drop a few tenths of a volt, but no more.

If it drops significantly when plugged into the laptop, the fault could be in the power supply or the laptop. If it doesn't drop significantly, the power supply is almost definitely OK and the problem is in the laptop. Like Bob, I would suspect the battery first.

#### Dang8701

Aug 20, 2014
10
i might have poked a capacitor with one of the mini screwdrivers i used to pop it open.

@KrisBlueNZ the flicker i mean is wheni plug the cable into the wall and measure the voltage on the plug that goes into the computer I get around 20-24 volts like it should be, but it spikes a few volts every few seconds. which causes the analog meter needle to jump a bit and it does this in a rythmic pattern like once every 1.5 seconds. Then when I plug the computer in with no battery the power light is on green but blinks off for a split second like once every 1.5 seconds too as in rythm with the previously read output of the cable.

I would show you by making a video, but im not in the mood to put this brick back together possibly ever after seeing this and jabbing a screwdriver so wontonly in there while taking it apart

#### Attachments

• IMGP5462.JPG
125.3 KB · Views: 134

#### Gryd3

Jun 25, 2014
4,098
i might have poked a capacitor with one of the mini screwdrivers i used to pop it open.
A word of warning.
That could have been potentially lethal.
Capacitors, unlike many consumer batteries have almost no limit to the amount of current they can unleash when presented with a conductive path. They are the reason that working on TVs and other mains powered devices are dangerous even after unplugging them from the wall.
When doing this kind of work, carefully dismantle the enclosure and avoid contact to the board with conductive tools. It is always ideal to leave the device unplugged for a length of time prior to give the capacitors time to self-discharge. (Can take up to a few hours depending on the circuit)
I am glad nothing happened, but please be careful in the future.

Also, troubleshooting that may be very difficult as we cant see the back, and there is a lot of items covering the front. It may not be worth digging into further at this time. Perhaps Kris can lend some thoughts on the subject.

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
12,613
A switched mode power supply needs a base load in order to function properly. If this load is not provided internally in the "brick", the output voltage may exhibit such pulses as seen by you. Connect a resistor (e.g. 1k) across the output of the brick when measuring the voltage. Does it still show the pulses?

Does the computer operate with the power supply plugged in? This would indicate that everything is o.k. with the power supply and the fault is either with the battery or with the charging circuit of the laptop. Can you find someone who has the same battery to cross check it in your laptop (or your battery in his laptop)?
If both battery and power supply show to be o.k., the problem is with the charging circuit within the laptop and you'r up for a repair (or a new laptop).

#### debe

Oct 15, 2011
276
I would suspect there is a problem with the powersupply. Ive just checked several, & they all give a stable voltage with no signs of pulsing you have, this is with no load connected.

#### Dang8701

Aug 20, 2014
10
yea you are pretty right about that Gryd. Especially since It was an all metal little thing, and the big capacitor in there is 450 volts. Never can remind someone enough about capacitors it seems. I actually got zapped three times just handling the thing. due to all the damn silicon there was no way to get in there to disccharge the legs

#### Gryd3

Jun 25, 2014
4,098
due to all the damn silicon ...
Repairing this device seems out of the question, especially considering you may have punctured a cap.
Do you have any ideas on how you want to proceed?
Radioshack was a let down, and you have not responded if any friends/family have any compatible parts you can try. You could always try another retailer that carries universal 'bricks' or you could try that scarey \$3 charger. (Test it first :S)

#### Dang8701

Aug 20, 2014
10
yea i plan to try to find a more decent charger than the 3 dollar one. I am relatively certain it was the cable, because I hooked up my voltage tester to the battery charging pins beneath the laptop and compared the pulsing of the needle to the pulsing of the green "plug in power source" light and they matched exactly. That kind of pulsing coming from a power brick in my limited knowledge of electronics probably means a failing or dead capacitor in the brick that is failing to hold a charge, discharging continuously once it gets to a few volts and releasing it into the computer. So I will try a new brick, and let yall know how that goes. ANyway I will test the voltage first.

No friends or family with anything similar, Ill have to buy it and it will take some days to order

Replies
3
Views
686
Replies
2
Views
2K
G
Replies
15
Views
1K
ghostwriter
G
J
Replies
13
Views
1K
sylvan butler
S
A
Replies
12
Views
1K
A