Image Map Image Map
Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 23

Thread: Might have ruined the motherboard on a Compaq Portable. Any suggestions?

  1. #11

    Default

    Quote Originally Posted by compaqportableplus View Post
    The 8-bit guy burnt a trace on his by hooking an external power supply to the internal one (sounded like a really bad idea to me). When you’ve got a board that won’t power-up, blasting more current through it is not the answer.
    It works if you know what you're doing. This is a good application for a current limiting supply.

  2. #12

    Default

    Quote Originally Posted by compaqportableplus View Post
    Have you checked the smaller orange ones? Pretty sure those can short too.
    I hadn't thought those were also suspect; Do you know of a suitable replacement? I'm having trouble hunting down the type used (looking in the Sam's Computerfacts).

  3. #13

    Default

    My apologies for the slow responses; everything I do requires moderator approval.

  4. #14

    Default

    Quote Originally Posted by KC9UDX View Post
    It works if you know what you're doing. This is a good application for a current limiting supply.
    I've seen this method referenced elsewhere, and it sounds like an interesting tool to have in my toolbox. I went ahead and bought a 0-30, 0-10 bench regulated power supply to try this out; I've really had enough trying to test tants; I think I'll try 12v 0.5A and see if I can put some alcohol (will have to try to find a suitable type) on the board.

    Here's the one I bought: https://www.amazon.com/dp/B07512KQDW..._y6afDbH215Y1Y

    Now hopefully I can find the failed component.

  5. #15
    Join Date
    Oct 2008
    Location
    Kamloops, BC, Canada
    Posts
    5,661
    Blog Entries
    43

    Default

    Quote Originally Posted by KC9UDX View Post
    It works if you know what you're doing. This is a good application for a current limiting supply.
    Precisely. 8-Bit Guy has a reputation for being a tool...
    = Excellent space heater

  6. #16

    Default

    Quote Originally Posted by Towmater View Post
    What's a good non-self-destructing replacement for tantalum capacitors?
    Niobium Oxide. But they only come in lower voltages.
    For example, I use 33 uF, 6.3 volt caps all over my designs for everything from the 5V caps on USB ports to the 3.3-volt main power plane for the electronics.

    New tantalum CAPs should out-last the product.
    I've got a large plastic storage bin FULL of reels of tantalum CAPs of assorted values and voltages.
    I suspect its worth a chunk of change.
    But you can buy 1 or 10 CAPs at a time from Digikey, Mouser, Newark, etc.

  7. #17

    Default

    So I hooked up the regulating power supply I bought to the board; first, I tried 5 volts through the 5v pin on the motherboard. Sure enough, the red light came on. My understanding is most of the work is done with 5v on the mobo, and 12v is mostly for the ISA slots?

    In any case, that's good news that it seems the board is not toasted; but still not really functional as the 12v is still shorted somewhere. I hooked up the supply to the board's 12v and ground and turned it on. The display showed 0v but around 1.1A being consumed. I've only let it stay hooked up for a few seconds at a time to hopefully avoid damage. None of the small tants popped, and I don't feel any warm components, so I'm still stuck.

  8. #18

    Default

    The way it was explained to me is that 5 volts was for electronics and 12 volts was for motors.

    Itís probably not quite that simple.

  9. #19
    Join Date
    Mar 2012
    Location
    Augusta, Georgia, USA
    Posts
    636

    Default

    Don't force power onto a shorted board, you will burn traces and other components. Just replace all the caps...

    NOTE: I have never tried applying extremely current-limited power. This may be a fine technique, but I am not an electronics expert to try this. You say it needs a heat camera? I've always used a meter to find shorts- if you have a good one you can narrow it down to a certain area of the board, sometimes.

  10. #20

    Default

    So long as you don't provide enough current to burn a trace, you still might have enough current to burn out a short. In any case, you can usually figure out where the current is going.

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •