Dell Dimension C521 motherboard

[kahlil88]

Need to replace several bad caps and possibly some seemingly good ones of the same series as preventative maintenance, but let me know if I'm just being paranoid. Very much open to replacing all or some with polymers but not sure what values to go with.

Bad caps are all 6.3v 1800uF (5x Rubycon MCZ + 1x Chemicon KZJ).

There's a row of clean 6.3v 820uF KZJ caps above the RAM slots and 2x 16V 680uF MCZ on the corner closest to the CPU fan.

[piernov]

Re: Dell Dimension C521 motherboard

Knowing this has a garbage Nvidia northbridge affected by bumpgate I wouldn't invest too much into it. At the very least if it's still working keep it well cooled.

[kahlil88]

Re: Dell Dimension C521 motherboard

Knowing this has a garbage Nvidia northbridge affected by bumpgate I wouldn't invest too much into it. At the very least if it's still working keep it well cooled.

Good to know. What's the best series to replace the bad caps with at least? I was looking at Nichicon HN to replace the KZJ but my understanding is the MCZ should only be replaced with polymers.

[kahlil88]

Re: Dell Dimension C521 motherboard

I forgot to mention sizes. The blown MCZ are 8x20mm and the KZJ are 10x16.

It seems the Nichicon HN series has been declared obsolete and I could only find a replacement for the 8mm MCZ caps. Had to dig through the BadCaps forum because Mouser hides it from search!

https://www.mouser.com/ProductDetail/647-UHN0J182MPD6TD

I can get cheap Würth Elektronik polys to replace both size caps. Same voltage and ESR, higher ripple. Capacitance is a little off, the 8mm being only 1200uF but for the 10mm I have a choice between 1500uF or 2000uF.

[piernov]

Re: Dell Dimension C521 motherboard

For solid polymer caps you'd typically use lower capacitance anyway.
For liquid electrolytics I like Rubycon ZLH, but other good low-ESR caps will most likely work fine.
Other people may have a different opinion but in my experience getting the exact same specs doesn't matter that much.
I don't have every single specs in stock so I use whatever similar cap I have and it hasn't been a problem yet. Solid polymer or decent low-ESR liquid electrolytics at least though.

[kahlil88]

Re: Dell Dimension C521 motherboard

I went with Würth and it works great. Just re-capped a second identical board and it won't boot if I install the RAM in pairs. Gives the beep code for memory failure but it works in separate channels.

I probably damaged the board fighting with this awful unleaded solder. Is there an easy way to test with a multimeter or should I just get another board? Maybe there's a less bad one that fits the same case...