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My DAC has exploded. I'm not kidding

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Mar 18, 2019
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#1
Hello!
I have rescued from the drawer a DAC Musical Fidelity X-24K and after being using it has begun to hear a lot of noise and then something inside has exploded after which has followed a strong smell of burning.

I show you pictures of what I have found inside, so you can give me your opinion and see if it has a solution or if I now have a nice paperweight.
The DAC continues to work but only noise and music are heard very little volume.

Look at the C16, BOOOOOM!!!!!
The black spots are remnants of the explosion.

Thanks for the comments!

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daftcombo

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#2
Not as bad as Notre-Dame, but still impressive. Did you use the power supply that was provided with the unit?
 

DonH56

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#4
Sometimes caps do just go bad and sometimes dramatically. What you do now depends upon your technical savvy. It looks like a 47 uF, 16 V tantalum cap so you could just replace it. But, it would be best to do a bit of troubleshooting to see if it was simply a bad cap or if something else has failed that killed the cap. And take a close look at all the other caps, as well as the power supply to make sure it isn't sending too much ripple out. If you do not have the tools and skills, you could ask a techie friend, find a local shop, or just contact Musical Fidelity for a repair estimate.

HTH - Don
 

DonH56

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#6
Power sources all go bad eventually so I would check it out to make sure it doesn't take out your other unit. But that's just me. If it is just a transformer then it is probably OK. If it converts to DC then there are things in it that could cause problems for the components it drives even if those problems are not immediately obvious. An abundance of caution, sure, but OTOH you have a blown DAC...
 

AnalogSteph

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#7
Nothing like a little dipped tantalum explosion to brighten the mood. These things have a tendency to fail short and may then literally go up in flames, as demonstrated here. (Apparently modern tantalums are non-explosive.) Generous derating is advised, as tantalums are physically quite small and low ESR and can have a hard time with inrush current. Owners of early devices equipped with them found out the hard way.

Doesn't look like major damage, apart from all the mess that'll need cleaning up. I would check what voltage C16 actually has to sustain in operation. The 16 V rated part would have been adequate for a +5V supply, but for something like 12 or even 15 V it would have been woefully underrated. (I almost suspect that C16/17 are +/-15 V bypass caps. Ouch.) If such a problem is found, check for a similar condition at other parts (measure or verify connections on PCB) - replacement of more tantalums may be advisable to prevent further explosive problems. I would recommend about the following minimum voltage ratings:
Conventional electrolytics: 1.5x-2x of sustained voltage
Dipped tantalums: 3x of sustained voltage

For obvious reasons, supply voltages should also be checked just in case. It does look like marginally-rated parts to me though.
 
Last edited:
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#8
That's correct - good suggestions. Tantalums also really dislike being installed backwards, but sometimes can survive 24hr burn-in cycles, if this was a very low use device. And yah, they have a very distinctive stink when their smoke is let out.o_O
 

amirm

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#9
It is nearly 20 years old. A cap self-destructed in my Mark Levinson DAC I bought around the same time (1999). I just replaced the cap and all has been well.
 
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#10
Considering that DAC's age, I'd investigate one thing before paying somebody to repair it: is the case ID large enough to hold a Khadas board?
 
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#12
We stopped using tantalums about 30 years ago: replaced with solid aluminium. Which were yellow. Yours may also be Al, and not Ta.

As for the derating, it looks like they're all 16V, 47u. Check what voltage it's actually handling. Looks to be inserted correctly, provided the silk screen is correct. Again, check the actual volts on the PCB pads.

It's most likely supply decoupling, so the device will almost certainly work with the dead cap removed. It just might not be quite so perfect.
 

restorer-john

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#14
This also looks suspicious:

1555625096235.png


I'd say you've lost one of your rails for the +/-V opamps. Power it up and check the rails marked on the connector.

1555625570423.png


As pointed out above, those Tantalums are on the edge for a +/-15V supply. I'd be replacing them all.
 
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Jimmy

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#17
Maybe you can check the power adapter output voltage before doing anything else, it's curious that two tantalums blew simultaneously. You shouldn't have any trouble replacing them with low ESR electrolytics, 47uf 25v Panasonic (EEUFR1E470H), for example, they will only cost a few cents so it doesn't hurt to try and see if that's all the damage.

I've never liked those 12V AC power bricks that MF shipped with their X-Ponent line, they got crazy hot (so did their tube amps without any venting, not the DACs, so here heat is not likely the cause of the failure).

Good view, the C15 has also been destroyed!!


View attachment 25143 View attachment 25144
 

Jaimo

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#20
I would replace all capacitors on the board. Modern polymer tantalum caps are a lot more reliable and don’t go up in flames. The operating life of aluminium electrolytics is roughly 10 years (mainly ambient temperature dependent) From the pics, your electrolytics look okay but I would replace them anyway.

Use good quality caps like Nichicon and Kemet for the tantys.

Your DAC should then be good for another 10 years.
 
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