I need blown caps replaced on a P5B Deluxe - Page 5

Hi Guys,

I know I'm replying to a 2-year old thread, but I'm hoping some of you are still around and can help, especially PizzaMan since he did the replacement .

I have the same problem and need the caps replaced on my P5B. I can do the work, but I'm trying to pick out the correct caps. Would you by any chance have a way to check what caps you used as a replacement? I can see from the caps on the board that they are 6.3V 1800uf 8x20mm Radial Can MCZ caps.

What I don't know is what impedance I should select. I don't see it anywhere on the cap itself, or on the specs i can find on the internet for the MCZ caps. I also see that the existing caps have a 2350 ripple current rating, and i'm not sure what that means or how close I have to be in the ratings.

Any help would be appreciated! I love the board and it's operating great still so I'd like to fix it before i run into any problems.

Thanks!
- edrz

The boards aren't to picky. Match the voltage with enough uF and you should be fine.

Awesome, thanks much!!

> Match the voltage with enough uF and you should be fine.

So does that mean any capacitor with a uf of 1800 or greater will work as long as it's 6.3v? Digikey's 1800uf 6.3v capacitors are only rated at 2000 hours, so I was hoping to get some rated for longer.

Sorry, I'm not that familiar with electronic theory.

2000 hours seems really low.

I thought so too. The entire 1800uf 6.3v list at digikey is rated 2,000-10,000 hours, which doesn't seem much to me. All the 8mm ones are rated at 2,000 hours at 105C.

That is an MTBF of 2000 hours if the cap is operating at 105°C the whole time. Decreasing the temperature will considerably increase the MTBF.

Ahh, that makes much more sense. I'll order them up then.

Thanks!

Hey,
I've been running on my P5B Deluxe/Wifi-AP for something like 5 or 6 years now. It's started crapping out, and I actually did a lot of other diagnostics to try to figure out what's wrong. I figure this might be useful for anyone still running on this old beast--a week or two, my computer began to randomly freeze in Windows 7. It started getting worse to the point where I couldn't stay booted. Did RAM tests, stressed other components, but everything else was fine. The only strange quirky behavior was that that it'd occasionally boot and say that the CMOS checksum failed and that the configuration was reset. Realized that there was something wrong with the CMOS RAM, and when I finally went to the motherboard to diagnose (I work on electronics so I'm pretty familiar with fixing this sort of thing). It turns out that modern motherboards store BIOS configuration and the clock in the southbridge, so I check there, and voila, a bunch of bulging, unhappy capacitors. Unlike the OP, the MCh (or whatever) caps are perfectly fine--just the same southbridge caps that are pretty dead (again, right next to my pretty hot GPU). There's a possibility that my EEPROM might be shot as well, but that seems unlikely.

Seeing that this is probably sort of the average lifespan when this particular mobo fails, I figured it'd be useful to let anyone who runs across this page as well--if you're running on a P5B Deluxe and your computer's doing funky stuff, I'd check those Southbridge caps.

Also, someone commented about capacitor life--indeed, electrolytic capacitors are never rated to more than 10,000 hours. Note though that this is usually at the maximum operating temperature (105C or 85C). The increase in life is usually something like about 2x life every 10 degrees Celcius. Interesting numbers--the caps that failed were rated to 2000 hours at 105C. 3 years continuous operation (I leave my computer on a lot--50% on is pretty accurate) is about 27,000 hours. Rule of thumb is about 2x life per 10 degree drop; this means the caps might've been running at 75C, which isn't what my southbridge temp measurements were, though it's not ridiculously off (like those motherboards back in the day that failed in a month or so). Anyway, these are crap "TK" brand ATWY series caps.

Well, if anyone runs into weird things going on their computer and have a P5B deluxe motherboard, it's probably either time to get a new mobo or time to recap.

Evilzoidberg: I'm actually curious, did you run into the same symptoms that I was?