Nubus card - Nuvista - Tantalum exploded with poweron

[Jenna16bit]

Hey there! I have a Nuvista card pair for my IIfx, the video capture and mjpeg cards. After inspecting & installing them, a tantalum cap on the daughter board exploded immediately. Beyond replacing the cap (I do have the value 68uf/16v), cleaning the boards with isopropyl, and checking along the connected line on the daughterboard, anything I should do? Are tantalums known to do this? Is there a safe way to check the voltage being supplied after removing the capacitor? I would assume bridging it with a multi-meter could be very bad.

 

[Unknown_K]

https://www.onelectrontech.com/tantalum-capacitor-failure-modes-and-causes-esr/

 

[Jenna16bit]

Interesting! It sounds like replacing any voltage regulators on the card would be wise.

 

[zigzagjoe]

Tantulums are 100% intolerant of reverse polarity or sustained overheating while soldering - are you certain they were oriented correctly? Odds of it being an issue with the power fed to the cap is low.

 

[Jenna16bit]

Yep! It was a factory installed tantalum on the card, so I presume it was installed correctly. Thank you.

 

[Byrd]

That's what they do, burn out when faulty. I'd just replace the failed part and inspect for any other damage, electrolytic caps replace too.

 

[Unknown_K]

I would just replace it and see if the card works.

 

[Byrd]

Yep admit I'm being too cautious, nothing like a single tantalum to replace and all should be well with it again.

 

[zigzagjoe]

Oh, sorry, I was thinking it was recapped. In that case, yeah, as other folks said that's just something tantulums do when they decide to fail. If it's going to happen, it's usually at power on and typically spectacular. I had an Asante MacCon do the same thing, tantulum exploded at power on.

Just replace and you ought to be fine.

 

[Unknown_K]

I have a Daystar 040 where a tant exploded, card wotks fine.

 

[Jenna16bit]

Thanks for all the feedback! I've ordered a couple replacements and also replacements for the on-card voltage regulators if it happens again. Now to track down a photo of the daughterboard that shows the correct polarity, or trace it out.

 

[Jenna16bit]

Also @zigzagjoe is that a Honda Cub in your profile picture? Curious how those feel in traffic.

 

[zigzagjoe]

Also @zigzagjoe is that a Honda Cub in your profile picture? Curious how those feel in traffic.

Haha yes it is! 1982. It's not terribly quick, but I love it. Definitely low speed roads only as 45mph is about the top reasonable and it takes some time to get there. Definitely requires some creative routing.

I also have a 2022 Honda Trail. It has a bit more power and will get up a bit above 40 reasonably quick and eventually to about 55mph. So it's more reasonable, though I still don't ride around traffic if I can help it. I call it my truck, pictured loaded up with a SE/30 for a vintage computer event.