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So, I'm the person who asked about that Compaq Presario 2500 laptop.

Well, guess what I found at another garage (well, it was smack dab in the middle of our local copy/paste American city) sale? Another Compaq Presario laptop! This time a 2200.

Compared to that sad socket 478 Pentium 4 and ATI northbridge based model, this one is build around intel's socket 479 Pentium/Celeron M platform.

Now, my Dell Inspiron 700m is based on the exact same platform. That Dell doesn't get hot, so I had pretty good hope that this laptop hadn't baked itself to death.

Well, the laptop doesn't work. Either this whole thing is a coincidence, or I'm doing something stupid. (Probably me doing something stupid.)

But now I'm thinking that, maybe, my power supply setup is the issue as I don't have the proper charger. The machine calls for 18.5V at 3.5 amps (~65W). My power supply does 18.5V at ~3.2 amps (~60W).

Could a difference of ~5W prevent the machine from posting? Honestly, I doubt it. The CPU isn't going to be at full throttle when it boots up, and a good chunk of the power gets slurped up by stuff like the disk drives. With EVERYTHING removed (everything from ram, to the battery, and both optical drives) the machine pulls 660mA. Oh, and the power supply is right on the money at almost EXACTLY 18.5V.

Idk, maybe there's some weird crap involving the barrel jack on the computer itself? I've been using Chinese clip leads and the cord off of Stanley the Omnipotent White Tabby Cat knows what, and the end plug doesn't fit the best.

Or maybe that USB port being crunched right in and shorted did something to the south bridge. I DID clear the short, but it the computer still didn't boot. (I did desolder that USB port, but it was late at night, I had just washed the motherboard, and I didn't get to test the laptop yet as I'm out right now.)

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    So I can't help but feel like you've given us a wide array of random statements without context like what you want to do, what you have done, or what happened to this usb port, why you would "wash" a motherboard, solder/desolder components, etc. I recommend you revise your question to make it less of a story, bring up topics clearly before digging into them, tell us when you have changed topics, and most of all clearly state what you have, and what you are trying to do. don't make us guess at which of the three laptops you mention is the one you are working on, or really anything else.
    – Frank Thomas
    Commented May 23 at 16:50
  • This site is for questions and answers to a particular issue.
    – DrMoishe Pippik
    Commented May 23 at 16:56
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    Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.
    – Community Bot
    Commented May 23 at 18:12
  • Sorry, but I do like to add context to my questions. I'd imagine it would be useful.
    – qwerty keyboard
    Commented May 24 at 11:37
  • @qwertykeyboard Detailed information is always preferred, however layout and formatting matters, creating a cohesive presentation of the information, which is where the issue lies with this question. The question, and the subsequent answer, would benefit from bulleted lists, numbered lists where steps are sequential and in order, paragraph grouping, and lack of commentary. Please see How to ask a good question?
    – JW0914
    Commented May 24 at 12:12

1 Answer 1

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Alright, the laptop works now. What did I do?

The whole motherboard was stripped down (including removing the CMOS battery!) and given a good scrub. Then it was left to dry in the sun.

The power supply? Out with the Chinese clip leads, and in with crimped spade connectors!

After verifying that, yes, the machine does post, I soldered in a new USB port.

The power supply is still ~5W short, so the laptop goes weird sometimes. I believe the issue might of had to do with the relatively high resistance from those clip leads.

Or maybe there was some dirt that was conducting between traces.

Either way, I'm glad to have a... Ugh... Completely obsolete computer at my disposal. Eh, it'll be fun!

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    How did you "wash" the motherboard? If with water (I'm assuming so since it was left in the sun to dry), that's going to damage the motherboard at some point due to the conductive minerals within water that are left on the PCB after drying - only safe way for a consumer to clean a PCB is with 90%+ isopropyl alcohol, which also dries within seconds. If motherboard was "washed" with water, immediately power it off and do not use it until the PCB has been thoroughly cleaned with 90%+ isopropyl alcohol to avoid damage to ICs and other components (hopefully none have been damaged already)
    – JW0914
    Commented May 24 at 12:02
  • Yep, soap and water! Left it out to dry in the sun. You just need to make sure stuff like clock batteries are removed, and let the board have ample amounts of time to dry.
    – qwerty keyboard
    Commented May 25 at 15:52
  • You cannot use water to clean any PCB and you are gauranteed to have an issue with your motherboard at some point because of it, as it will eventually cause short circuits within components due to the conductive dissolved minerals water naturally contains, of which are leftover on the board once the water has been dried off the surface. There is no way to avoid that, which is why water cannot be used to clean PCBs and why 90%+ isopropyl alcohol must be used (any solution lower than 90% risks the same minerals remaining behind since a 70% solution would be 30% water).
    – JW0914
    Commented May 25 at 18:02
  • It'll be fine. The world isn't going to end. Now, when it comes to moisture content that CAN be an issue, if I ever had to do BGA work on it, but PCB's will slurp up trace amounts of moisture from the air, and applying a gentle level of heat will drive it away.
    – qwerty keyboard
    Commented May 25 at 22:23
  • The minerals left over when water dries are often not visible to the naked eye (sodium often is, esp. in softened water) and they will cause short circuits to occur between the feet of solder pads on the board - this isn't a hypothetical if it will occur, it's when will this occur, and once it does, the IC or component the short occurred on will be fried. If it's worth doing, it's worth doing right the first time. Magnesium, iron, calcium, sodium, zinc, and fluoride are all conductive minerals commonly found in water (these are what make water conductive - pure water is not)
    – JW0914
    Commented May 26 at 9:19

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