Little Caps can be BAD

[bigbeark]

Here's a Pic of my Asus TR-DLS motherboard with onboard SCSI that is misbehaving. The little caps I believe are 10uf 25v and a grouped near the SCSI chip. I measured their ESR. It was 8(!!), I'll be recapping as the board works great other than this issue.

[Topcat]

Re: Little Caps can be BAD

Thats certainly possible, just not very common. On the SX280, theres a 22uF @ 25v by the CMOS battery that fails all the time. Strange one to fail, and many times fails without showing any physical signs. It will usually just go open, and make the board exhibit all kinds of odd behavior.

[shovenose]

Re: Little Caps can be BAD

Thats certainly possible, just not very common. On the SX280, theres a 22uF @ 25v by the CMOS battery that fails all the time. Strange one to fail, and many times fails without showing any physical signs. It will usually just go open, and make the board exhibit all kinds of odd behavior.

do you know what circuit this cap is part of?

offtopic question for topcat: do you know if, on a dell 270 sff p4, the 1 rubycon cap sort of in the middle of the mobo leaking crud can cause the onboard lan to not work?
thanks.

[bigbeark]

Re: Little Caps can be BAD

do you know what circuit this cap is part of?
.

Since these caps are right beside the 68-pin onboard SCSI connector, I am assuming they are in this circuit.

[RJARRRPCGP]

Re: Little Caps can be BAD

do you know what circuit this cap is part of?

the 1 rubycon cap sort of in the middle of the mobo leaking crud

I would think the problem would be more serious than the onboard ethernet being unusable.

[bigbeark]

Re: Little Caps can be BAD - UPDATE

So I replaced those little stinkers. When I got them off the board they all measured around 4
ESR value. Replaced them with Nichicon PY 10uf 25v. There were 6 scattered among the SCSI chips. A real swine to remove and clean out the holes. Made extensive use of the "add fresh solder" to remove the caps and also to melt the solder in the hole for the pin-method. All went according to plan. I noted that the previous owner had set the onboard scsi jumper to disabled. Changed that and attempted to boot from the harddrive. Realized that the HDD had Adaptec drivers loaded and the on-board is LSI, so that didn't work. Did a fresh install of Ubuntu, crossed my fingers, and voila! Success, boots and runs fine.

The board still needs a recap though. It's responsive, plays video etc, but I got it to freeze by loading a CD into the tray while a youtube video was playing. Locked up the video, lost the mouse. Had to restart. A little later lost the mouse again. After that I got a lock when I tried to change the Desktop background. This is over the course of three evenings.

I figure server boards should just automatically be recapped, the caps are just "tired".
I'll start with the 6 Nichicon HD(M) 1220uf 16V from 2002.

[smason]

Re: Little Caps can be BAD - UPDATE

I figure server boards should just automatically be recapped, the caps are just "tired".
I'll start with the 6 Nichicon HD(M) 1220uf 16V from 2002.

Server boards? Server and Asus shouldn't be used in the same sentence.

[shovenose]

Re: Little Caps can be BAD

are nichicon hd supposed to not have colorful sleeving? or if mine dont does that mean they are fakes?

[severach]

Re: Little Caps can be BAD

do you know if, on a dell 270 sff p4, the 1 rubycon cap sort of in the middle of the mobo leaking crud can cause the onboard lan to not work?

Most boards won't post when C259 on the GX270 SFF board goes bad. Apparently the heat from the nearby MOSFET is "to die for."

Measure the cap voltage then check the voltage against the required voltages on the network chip datasheet. Looks to me that the RC82540EM takes a lot of 1.5v and a little of 2.5v and 3.3v. Without the 2.5v and 3.3v it can't communicate, and without the 1.5v it can't function.

[ratdude747]

Re: Little Caps can be BAD

i think the HD is ok... it is HM and HN that are stinkers.

[shovenose]

Re: Little Caps can be BAD

It is c259! Well it still seems to be working. And the lan still works too. Just need to keep an eye on it!

[Rulycat]

Re: Little Caps can be BAD

I've never seen problems with caps on cool-running devices such as the super cheap network cards where they use the ridiculously cheap generic brands, not sure why they last so long.

[Pyr0Beast]

Re: Little Caps can be BAD

They don't. Just that caps on mobo have to take the burden then.

They are also quite tolerant, unlike other systems.