My adapter just died - 20V + 4.7A

[Santa]

My laptop adapter just died (they never last)
it is 20V and 4.7A
Siemens wants to sell me a new one for 100$.....
my machine is not even worth that.

Question
i have found several different cheap adapters but none of them fit exactly the same Volt and Ampere output.

i found one
20V 3.5A
and
18.5V 4.9A
and
16V 4.5A

would any of these do?
what is the most important the Volt or the Ampere?
or should i seriously try to get the right output?

I will scrounge the pc shops tomorrow for second hand -but if i come across any which are slightly off V and A wise is it safe to use them?

thanks in advance

[Virtualbody1234]

Make sure that the Voltage is exactly the same and that the Amperage is the same or higher than specified.

[clocker]

VB is exactly right (no surprise there).
Obviously having the correct voltage is crucial.
The amperage is important because the ac adaptor is not only running your laptop but recharging the battery as well.

If your whole laptop isn't worth $100 have you considered an upgrade?

[backlash]

my adapter makes a crackling, beepy type noise when it's in use..it's prolly going, too.

[clocker]

my adapter makes a crackling, beepy type noise when it's in use..it's prolly going, too.

The adaptor itself or the lappy's speakers?
If you adaptor is making any noise whatsoever UNPLUG IT IMMEDIATELY!
That is a solid state device and really isn't capable of making any sound at all during normal operation.
A malfunctioning ac adaptor can really screw up your pc...don't risk it.

[backlash]

it can really screw up my laptop? I don't have another adapter and I have to use it b/c my laptop battery doesn't hold a charge for longer than a few minutes. I can have it be 100% full and a few minutes later it's at 89% and so on and so forth. my laptop's speakers also make noise when downloading stuff or doing things that require a lot of cpu and memory. (why does that happen?) I guess I'll look for a new adapter.

[Santa]

Thank you for the information - i dont want to destroy my laptop just yet.
I will now go off in search of the holy adapter with right Amperage.
Thank you

Will definetly upgrade soon as money is sufficient.

Adapters always seem to die first whether mobile phone etc etc

[lynx]

What model is your laptop? More importantly, what voltage does the battery operate at (it will be marked on the battery somewhere).

The reason I ask is that in order to charge the battery, the input voltage from your adapter must be above the nominal battery voltage, usually by about 20%. So if your battery operates at 15V, the required voltage for charging will be about 18V, so the 18.5V adapter may well work.

Adapters like these are usually unregulated, which means that the voltage they give out varies quite considerably depending on the load. That being the case it is their power output which is important. The original adapter provides 94W, the 18.5V adapter provides 91W. The difference is negligible.

In any case, it certainly won't do any harm so if you've got the opportunity to try it I'd say give it a go.

[tesco]

my adapter makes a crackling, beepy type noise when it's in use..it's prolly going, too.

Do you smell any burning coming from inside the adaptor?

Also if it's your speakers you could try turning off the MIC in sound options, usually even if you dont have a mic plugged in it pics up noise from your har ddrive or something else (magnetic waves? ).

[Santa]

@Lynx - i never understood the difference between A & V - thanks for your explanation.

I was miraculously lucky enough to find the exact same adapter for only 20$ in a pc shop - it came from the same laptop which was completly destroyed. I am grateful for faulty manufacturing.