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i am good with computer hardware, but when it comes to power supplies and ac adapters, i am not quite sure about the voltages and amperage and stuff.


my laptop (clevo m570ru) had a 3 pronged ac adapter with output of 20v and 6A, That AC adapter broke. Now the only adapter that fits my laptop is 2 pronged 19V 6A adapter.

It powers up my laptop fine but i am nervous if can possibly damage mt laptop.

anyone here who is good with power supply stuff can answer this?

There would be more likely damage to the adapter from it pulling a bit more amps. You're probably OK though. You are allowed 10% on most voltages so you're still only about 5% off. This will however make your battery take a tad longer to charge and pull a bit more amps while charging (5% more). Just check your BIOS and make sure your 3.3, 5, and 12V are all OK. I'll bet they are. Most adapters are 2 prong now, but 3 is better for surge protection.

It dosent say the wattage on the AC adapters (which is always so annoying) but the original one for this laptop is a 125W but the one i am using now is 75W.

i definatley know that the lack of of wattage can cause permenant damage to system components, its like organs being damaged from lack of blood.

Well this is bad,

i ordered a new AC adapter.

In the three proged one you get leakage protection due to the earth terminal. Any stray leakage currents will be pulled to earth to avoid damaging components and from giving hazardous shocks, so its always better to stick with the three pronged ones.

Adapter outputs are DC. So the Real Power in Watts is given by
W = V * I
Your original adapter has a power rating of 20*6 = 120 W

The two pronged one has a power rating of 19*6 = 120-6 = 114 W

The voltage rating is out by 5% and that is not really acceptable because after voltage conditioning the core voltages might be off by more than their tolerance limits
However the current rating is what decides how much the load is pulling.
The current rating is the same 6A so there might be a marginal overheating of the adapter because of the lower voltage, if at all. Nothing serious.

Whenever looking for an alternate adapter the rule of thumb is make sure that the voltage rating is exactly the same, because circuits are generally designed to a specific voltage.
The current rating should be the same or higher.

If you can get a new one with the right voltage and amp (or higher) rating ... then why try the 19v one in the first place? If you can't get a new one I'd use the 19V one personally as I don't really charge my battery much. It stays full. However I'll bet you it'll work fine. DC voltage is not like AC voltage. Most voltages in a computer are lower than 12V. When converting from higher dc to lower dc the most common is to use a voltage a regulation circuit instead of resistor dividing circuits. These are figured with a 10% or more tolerance almost always because of varying battery voltages as it drains. The AC adapters are also figured for the same 10%. The only thing you lose with the lower voltage really is it will pull however more amps that you drop the voltage as long as you're in the 10%. You're 5% low so it will pull 5% more amps and you really should have a 6.3A instead of a 6A. However unless the battery is fully dead and you are using everything all at once in the laptop it'll probably never be fully loaded anyway. Your monitor may use 15v or so but I'll bet it's still in tollerance. My laptop @ 19.5V only comes with a 3.34A adapter. It also comes with an 11V battery so you can tell the internal circuits are figured to run off lower voltages. They also don't put the wattages on adapters really because of efficiency. The wattages are reported on the line side. 2 adaptrers from 2 different manufacturers ... one good and one really cheap ... rated at 120W may not provide the same wattage on the output side. That's why in the old days you'd see 2 different ones at say 120W, 12V ... but one may be 9.7A and one may be 9.5A and neither really gave you the full 10A by the wattage.

If the regulator is 20V,6A rated the circuit will be designed to pull a full load of approx. 25% less than the power rating of the regulator. That would be good design, because voltages always drop off at full load. So I don't think even at 19V the circuits would ever reach the peak current of 6A. If they do then the adaptor would overheat because the regulator IC would never be able to supply more than 6A, t's peak current rating.

It is also a moot point whether 20V is not required to drive other circuits than the ones that just provide the core voltages. In case they do, the lower voltage would result in erratic circuit functioning.

Also a change in voltage does not necessarily mean a proportionate change in current. It depends on the circuit in question the voltage-current characteristics of that circuit, and which part of the load-line the circuit is operating in.

wow you guys are hardcore