68kMLA Classic Interface
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| Nubus card - Nuvista - Tantalum exploded with poweron | |
| Posted by: Jenna16bit on 2024-07-30 17:27:32 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. | |
| Posted by: Unknown_K on 2024-07-30 17:31:13 https://www.onelectrontech.com/tantalum-capacitor-failure-modes-and-causes-esr/ | |
| Posted by: Jenna16bit on 2024-07-30 17:40:35 Interesting! It sounds like replacing any voltage regulators on the card would be wise. | |
| Posted by: zigzagjoe on 2024-07-30 18:13:04 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. | |
| Posted by: Jenna16bit on 2024-07-30 18:20:56 Yep! It was a factory installed tantalum on the card, so I presume it was installed correctly. Thank you. | |
| Posted by: Byrd on 2024-07-30 20:43:23 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. | |
| Posted by: Unknown_K on 2024-07-30 21:20:19 I would just replace it and see if the card works. | |
| Posted by: Byrd on 2024-07-31 18:15:07 Yep admit I'm being too cautious, nothing like a single tantalum to replace and all should be well with it again. | |
| Posted by: zigzagjoe on 2024-07-31 18:19:40 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. | |
| Posted by: Unknown_K on 2024-07-31 19:18:28 I have a Daystar 040 where a tant exploded, card wotks fine.  | |
| Posted by: Jenna16bit on 2024-08-02 07:35:34 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. | |
| Posted by: Jenna16bit on 2024-08-02 07:48:25 Also @zigzagjoe is that a Honda Cub in your profile picture? Curious how those feel in traffic. | |
Posted by: zigzagjoe on 2024-08-02 08:45:54Also @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.  | |
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