Thank you for this forum

Discussion in 'General Electronics Chat' started by WrinkledCheese, Jun 6, 2010.

  1. WrinkledCheese

    Thread Starter New Member

    May 30, 2010
    Thank you for this forum.

    I had to find out if what the guy at the local industrial electronics shop said was true. And I found my answer, along with many others, here.

    I need to replace a capacitor on my motherboard, and I hope it's the only one. The system seems to be working fine, except I can't tell because the video doesn't work. I tried 3 different video cards and they all work in other systems. I found a capacitor with a mushroomed top right by the AGP card slot on the motherboard and I followed it straight to the pins for the AGP card slot. The capacitor I removed, very painstakingly, was 1800μF 6.3V. The only shop in town didn't have any 1800μF and the lowest voltage they could order was 10V. I was curious why they put a voltage rating on them if they didn't really matter and now I know...and knowing is half the battle. Plus this falls in line of what he told me "you can always go higher in voltage" although it seems that is not always true.

    P.S. It's a polarized(+/- marked...well neg. anyway) aluminum capacitor. They tried to get me to series up two HUGE capacitors that made it about the size of a AA battery. I said "No, can you order one? I really don't have room on the motherboard." He really tried to get me to take the two caps that measured up to 1800μF. He showed me different combos and he was like how small is this cap, then I showed him in comparison a 1000μF that was about the size...I seem to have misplaced it though.

    This site has been awesome for my meanderings in circuitry. It all started when the HD on my XBOX died and I had to build a circuit to get the HD password from the EEPROM/BIOS and I saw how easy it was to fix things with circuitry. I really would like to take a course but, I have no time or money, so I have to learn it as I go.

    Thank you all again!
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    The Ebook is free and useful.
  3. eng1ne


    Dec 4, 2009
    If you wire two capacitors in series to achieve 1800 uF, the capacitors will both need to be 3600 uF (large).

    If you wire two capacitors in parallel to achieve 1800 uF, the capacitors will both need to be 900 uF (smallER, though not a standard value, the nearest would be 1000 uF).

    1800 uF is not a preferred capacitance, and whilst they exist, they will be difficult to find.
  4. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    When replacing mobo caps, there are a couple of things you should keep in mind.

    One is the size, sometimes u can get away with this.

    Next capacitance and voltage. They should be same, only slightly higher is OK but here it tends to change the cap size. So better to stick to the rating.

    Next is the operating temperature, nominally caps are at 85 degrees, bu tmobo caps are at 105 degrees.

    Last, and very important, cap should be low ESR type.

    Another thing to keep in mind is why the cap bulged.
    In ur case a 6.3V one. Means a 5V regulation could be a cause, if so U need to check the PSU for bulged caps, and check, preferably change all the 6.3V caps.
    Later case is that it sometimes is a factory fault, meaning those batch of caps are going to bulge one by one.

    Get the idea