This is a repost of an earlier question and though some people might find the answer interesting for future reference. My friend is a programmer (I'm sorry...hehe) with an Electrical Engeneering degree from Viginia Tech., so the source is reliable. Name: arkhive Date: October 30, 2002 at 18:25:16 Pacific Subject: Compaq Armada OS: 98 CPU/Ram: ? Comment: I have a Compaq Armada 4110D... My cousin accidentally plugged the wrong adaptor (Printer's Adaptor)... Since then,,, the notebook never again powered-up... The Voltage of the notebook's adaptor was 18.75V with the +ve polarity in the middle... The printers' adaptor was a 9.5V with the -ve polarity in the middle... I am hoping that it's only a fuse or cirvuit breaker that's causing the problem... NOW... the question is: IS THE MOTHER BOARD FRIED??? IF NOT WHAT CAN I DO TO MAKE IT RUN AGAIN(hopefully)???? THANX FOR ANY ADVICE Report Offensive Message For Removal Response Number 1 Name: PaCo Date: October 30, 2002 at 18:42:41 Pacific Subject: Compaq Armada Reply: Your Systemboard should be pretty well dead. Cut you losses and be glad it didn't catch on fire (I'm not kidding on one). Email me or post here if you want the technical reason, but it's shot. Report Offensive Follow Up For Removal Response Number 2 Name: arkhive Date: October 30, 2002 at 18:55:48 Pacific Subject: Compaq Armada Reply: I was hoping that it was just a braker or fuse... but... what can I do.... Will it fry the motherboard eventhough that the voltage is smaller?? Please enlighten me... :o) Thanx in advance... Report Offensive Follow Up For Removal Response Number 3 Name: Dave357 Date: October 30, 2002 at 20:29:45 Pacific Subject: Compaq Armada Reply: Arkhive, the lower voltage shouldn't have caused any problem, but the reversed polarity might have. HTH Dave Report Offensive Follow Up For Removal Response Number 4 Name: PaCo Date: October 31, 2002 at 12:51:43 Pacific Subject: Compaq Armada Reply: The technical term for why you don't want to put a wrong voltage and polarity through a power supply is called "Junction Failure". First - polarity - the transistors are expecting to have a certain amount of volts go through it in a certain direction. Going the wrong way through that channel causes friction (like running you hand against the fur on a dog). Friction causes heat, heat causes melting, melting causes trouble. the transistor gets shot. Second - Voltage - Think of the series of transistors as a maze with doors. If half the voltage is trying to go through a "door" (transistor), there may not be enough force to open some of the "doors". That leaves extra volts that need to go somewhere. Eventually down the chain, these extra volts can add up to alot (remember theres thousands if not millions of transistors on a board). Sending too much voltage through one of the other doors. It's like kicking in a delapdated door. The trans. are weakened by currents going the wrong way. Remember that all this power is traveling in circles, and you can get volts going the right way until they hit a transistor that has volts coming in the oposite direction because of the reversed polarity. And thats the second (well, technically the third...hehe) bad things that can ruin the board. These two (or 3, but whos counting?) together is what kills the board. And thus, why you don't want to do it.

I don't understand people who take pleasure in other peoples misfortune?

There is a fuse on the mb where the dc jack is and there is a diode right after the fuse for the reverse polarity protection, in this case the Cathode of the diode is connected to the + of the jack and the Anode is connected to the Gnd (Negative), so if the minus from the wallwart is connected to the computer Plus the diode will conduct and blow the fuse (surface mounted fuse). Have the Tech check it out.