Ouch that's not good, I can see where it left a crater in the epoxy.

Maybe the seller can help out or possibly refund.

https://www.dosdays.co.uk/topics/retro_review_pas16_pt2.php

The MVA416 is the codec chip. As you can see from the first model revision (650-0022-01), it's actually just a rebadged Crystal CS4216-KL codec.

https://www.ebay.com/itm/324735163523

Unknown_K wrote on 2024-04-04, 07:03:

https://www.dosdays.co.uk/topics/retro_review_pas16_pt2.php

The MVA416 is the codec chip. As you can see from the first model revision (650-0022-01), it's actually just a rebadged Crystal CS4216-KL codec.

https://www.ebay.com/itm/324735163523

well that makes replacing it pretty easy ! but something caused it to short so more investigation is needed.

I would check all the capacitors (especially the tall yellow ones) and resistors around the chip.

Unknown_K wrote on 2024-04-04, 07:08:

I would check all the capacitors (especially the tall yellow ones) and resistors around the chip.

The tantrum caps look good but I know from experience that this means nothing with the little caps of death.

Unknown_K wrote on 2024-04-04, 07:03:

The MVA416 is the codec chip. As you can see from the first model revision (650-0022-01), it's actually just a rebadged Crystal CS4216-KL codec.
https://www.ebay.com/itm/324735163523

Wow thank you so much. I didn't think it would be that easy!

Trashbytes wrote on 2024-04-04, 07:05:

well that makes replacing it pretty easy ! but something caused it to short so more investigation is needed.

100%, microscope time

Unknown_K wrote on 2024-04-04, 07:08:

I would check all the capacitors (especially the tall yellow ones) and resistors around the chip.

Yep I'll do that. Going use a ESR meter to check the caps while in circuit. Need to find what value these caps and resistors should be.

zuldan wrote on 2024-04-04, 07:15:

Unknown_K wrote on 2024-04-04, 07:08:

I would check all the capacitors (especially the tall yellow ones) and resistors around the chip.

Yep I'll do that. Going use a ESR meter to check the caps while in circuit. Need to find what value these caps and resistors should be.

Tantrum caps are nasty beasts and may check out fine but fail when voltage is applied, so really just check them to see if any are shorted not sure you will get any useful readings from testing them like electrolytic caps. (They also dont like reversed voltage in the slightest...something to be mindful of)

Something else I remembered is that solid Tantalums have a very low ESR so any that dont should be suspect.

Trashbytes wrote on 2024-04-04, 07:21:

Something else I remembered is that solid Tantalums have a very low ESR so any that dont should be suspect.

I measured the tantalum near the chip and it has a high ESR. So now I need to figure out what that tantalum is rated for. Will get out the microscope tomorrow and see if I can read any sort of value on it.

Bingo! Found the problem, as you guys said it was the bloody tantalum capacitor closest to the chip. It is shorted! I'm kicking myself now for not checking all the tantalum's before powering on the card.

Here is the value...

Looks like Jaycar sells them https://www.jaycar.com.au/10uf-16vdc-tantalum … acitor/p/RZ6648

That's great you already found it 😀 I wish you luck with getting the card working again.
Personally I don't think you should blame yourself too much for this really, you're not the first person this has happened to: Re: Media vision Pro audio spectrum 16 compatibility List
This wiki page doesn't mention them failing either: https://caps.wiki/wiki/Media_Vision_Pro_AudioSpectrum - Some people would say that tantalums are better since they can't expire from over-use like electrolytics can.

It's kind of surprising to me that a 1992-ish device has failing tantalums though, I thought that was earlier stuff only but I've seen those go pop on a 486 board so I guess it just happens to that type of tantalum unfortunately.
Probably better / safer to replace them with electrolytic caps rather than like-for-like, kind of a shame since the tantalums are part of the look of the card.

+1

Tantal(ums) condensers are usually being very high quality and long-lived, under the assumption that a given circuit is running over long time.

When in long storage, though, tantalums can "forget" their polarity and have a hard time when being exposed to power again.
In that moment, the caps have to go through some sort of reformatting process.

In which they can explode or short, at worst. That's because gases and other chemical things build up too fast inside.

To prevent this, in theory, old tantals would have to be charged slowly after long sleep.
By increasing the supplied voltage slowly over longer time.
That way, they would finally recover, maybe.

Speaking under correction here, though. That's merely what I've been told.

I'm pretty sure this applies to electrolythic capacitors in which the oxide layer dissolves into the electrlyte over time when they are not in use. Upon applying power it'll reform again although if it is far to gone it can cause some unpleasant effects, depending on size of the capacitor and how much headroom the system in question has for loss of capacitances. (i.e in a switching PSU this can mean than very high voltage pulses go through into rest of the circuit, potentially killing it).

Old tantalums going poof is a result of water ingression into the package from what I have understood. It is a problem with only certain types of such capacitors, and certainly not a feature of all of them.

The Crystal chip has been ordered. Should I be replacing all the 10uF 16V Tantalum Capacitors on the board? There are 16 of them. Only 1 has a short.

zuldan wrote on 2024-04-05, 09:05:

The Crystal chip has been ordered. Should I be replacing all the 10uF 16V Tantalum Capacitors on the board? There are 16 of them. Only 1 has a short.

If they check out ok and didn't pop the first time it powered up I wouldn't change them, but others here may have more experience with tantrum caps.

I’ve heard some dying electrolytic capacitors can be brought back to life kinda after being exposed to voltage for long enough, not sure how accurate that is. I always assumed tantalum’s would outlive electrolytic, I knew their failure state wasn’t great but didn’t imagine one could fail so quickly and badly like this. Maybe they’re not so much better than electrolytics after all…

midicollector wrote on 2024-04-06, 02:22:

I’ve heard some dying electrolytic capacitors can be brought back to life kinda after being exposed to voltage for long enough, not sure how accurate that is. I always assumed tantalum’s would outlive electrolytic, I knew their failure state wasn’t great but didn’t imagine one could fail so quickly and badly like this. Maybe they’re not so much better than electrolytics after all…

They both have different failure modes, Tantalums degrade when sitting unused for many years and lose their polarity when being re energised they can go one of two ways. Either they fire up and remember their polarity or they dont and die in a rather impressive bang. Tantrums being ceramic can also absorb moisture from the air around them when sitting unused, this also causes explosive failures. Electrolytic s tend to dry out and can take several power cycles to regenerate or they have already failed and leaked/burst whiuile sitting unused, they dont tend to explode but I guess its possible via over pressure due to an internal short/failure.

I have been trying to find info about this loss of polarity in tantalum over time and my search yields nothing, I'm most curious about it...
But what I did find is that there are filaments growing inside tantalums which can result in catastrophic failures, although in many cases they break down without damage according to a NASA study about failure modes in some types of tantalum capacitors.