Capacitors - Testing / Replacement

[Flinx]

Hi,

I have two motherboards. One does not work at all. The other almost works well.

The "almost" working one has two problems:
1) one memory slot is not good
2) the AGP slot does not seem to behave properly. I can
____load windows but if I try to increase the graphics
____resolution then all hell breaks loose.

I thought I might salvage capacitors from the "bad" board if I could determine good from bad on both and that was the problem. (No bulges and no leaks are apparent).

I just got through a session with an analog multimeter, not that I know a great deal about what I'm doing, and the large capacitors seem to behave properly (on both boards). The meter is zeroed to Ohms. Connecting the terminals, the needle swings and then drifts back. With the smaller capacitors the needles just stay high and this seems rather strange but it looks the same on both boards.

Is this going to take an oscilloscope? Maybe I should just say a prayer over my old board and bury it.

Any help or advice people?


The loving are the daring!

 

[DCB_AU]

Digital meter with capacitance option is required to test capacitance properly. All your reading is the caps charging up with meter needle deflection and you can't tell what value in farads- eg. micro, etc.

Small caps won't show chargeup as value to small- with analog meter.

If boards not the same, caps are not likely to be either. Check for any values on caps and replace with same from electronic store or just chuck out board as other probs could be present or likely to occur in future as parts stressed.

With AGP slot, use contact cleaner and put card in and remove a few times to clean contacts in slot. I've fixed problems like this before caused by grease and oils from fingers on AGP card.

Memory slot is no problem as don't use.



<font color=red><b>DCB</b></font color=red><font color=white><b>_</b></font color=white><font color=blue><b>AU</b></font color=blue>

 

[Crashman]

There are some fairly common values for motherboard capacitors, I salvage lots of caps. You can't just go to an electronics store and get the caps you need, they never have the right values in stock.

<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>

 

[Flinx]

Ok,

Thanks for the pointer on the memory. I'll try cleaning the contacts for the AGP as you suggested but I think there is a real problem. I have tried more than one graphics card and they behave the same way.

There was add on memory on a/the graphics card that burned out when the system started misbehaving.

I have salvaged the caps from the "bad" boards. The analog meter shows even the small ones fine now.

I'll keep the caps as spares as I agree with Crashman that the proper size capacitors are difficult to find; not being a technician myself anyway I wouldn't know were to look aside from a big electronics store and they don't have stuff like this.

I can't determine the problem on the almost good board. I guess I'll keep it around in the hopes of some light being shed on the problem someday. Maybe I'll run in to someone with equipment and I could make a learning experience out of it.

Anyway, thanks guys.



The loving are the daring!

 

[Crashman]

Yes, Asus boards are an excellent source for capacitors. So are old Abit boards, before the capacitor fiasco they used Sanyo caps.

<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>

 

[Rugger]

What caps are they using now?

__________________________________________________
<font color=red>You're a boil on the arse of progress - don't make me squeeze you!</font color=red>

 

[DCB_AU]

Yes I agree some caps are hard to find and some are impossible to find, but MB, etc manufacturers spend a lot money in design, to get the optimum spec of components so board, etc operates best.

Depending on what the caps in question do, you can get away with a little variation. If they perform criticle duties/or and work with other add on components eg. Graphic Card, Memory, etc, you could be stressing these parts and reducing there duty cycle/hours.

<font color=red><b>DCB</b></font color=red><font color=white><b>_</b></font color=white><font color=blue><b>AU</b></font color=blue>

 

[Crashman]

I don't have a recent Abit board handy to compare to. Abit always used name-brand caps before and after their experiment with commodity-grade caps, the brands I favor are Rubycon (most Asus, Aopen boards), Nichicon (most Intel boards), and Sanyo, but I've probably spelled at least one of those names wrong.

<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>

 

[Crashman]

I've never had a major brand capacitor fail from age. They tend to last around twice as long as the usefull life of the board they're mounted to.

<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>

 

[slvr_phoenix]

Book One: How to combine capacitors with a nine volt battery and a wooden pencil (with a metal eraser holder) for fun and profit.

<pre> <font color=purple>I express to you a hex value 84 with my ten binary 'digits'. </font color=purple></pre><p>@ 185K -> 200,000 miles or bust!