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Why did magic smoke come out of my Nuforce HDP?

post #1 of 10
Thread Starter 

Not 100% a DIY question, but I know there are some amazingly knowledgeable people here who might be able to explain.

 

Basically, I hooked up a new, regulated power supply (Goldsource 13.8V 5A from Amazon) to my Sonic Impact Super T-amp (TA2024 based) and I heard some rice krispies (snap, crackle, and pop) from my Nuforce HDP and then saw magic smoke and smelled the sweet aroma of cooked electronics.  My HDP is my audio hub and was hooked up to the T-amp via the HDP's analog out (RCA).  Inputs are through USB, optical, and analog in (RCA) and all were hooked up.  The HDP was on, but the amp was not.  I think that the power supply was on when I plugged into the T-amp, and the power plug wasn't fully seated before this all happened.  The RCA cables I used were some DIY 4 wire round braid cables that had never given me a problem before.  Prior to the regulated power supply, I was using a normal wall wart with no issue with any of the equipment.  

 

I am quite relieved that so far, at least through the headphone out, the HDP is still working from all three sources.  However, I am scared to hook my amp back up to my HDP at this point.  I don't know how my HDP is still alive after smoking, but I'd l like to keep it that way.  I am back to a wall wart for my T-amp.  And for more data, I have another DIY T-amp (TA2020 based) that I tried first and had zero issue with, although I had a different source hooked up to it.  If it matters, the T-amp is in an aluminum case, while my DIY is in a plastic box.

 

I'd appreciate any thoughts on what happened.  I only know enough about all this to get myself in trouble.  Thanks!

post #2 of 10

You may want to check that Goldsource power supply.  It's possible that the power connector is reversed.  Most walwarts work on the on the center connector in the male plug as positive, but there are few out there that are reversed.  If this was the case, then you would have shorted out the power supply to ground through the NuForce HDP and that could've caused the smoke.  (The RCA jacks would use negative as Ground.  If the Goldsource power connector was reversed, then the RCA jacks would've been exposed to positive voltage, feeding back into the NuForce.)

 

OK, doing a little research, it appears that the Goldsource products are bench power supplies.  In other words, you would've been responsible for connecting "-" and "+" to the connector that went into the T-amp.  Could you have reversed the connections, "-" and "+"?

post #3 of 10
Thread Starter 

Thank you so much, Tomb.  I tested the power supply on a different t-amp that I had purchased off of ebay, and it worked fine so I am assuming I had the polarity right.  That t-amp was not hooked up to the HDP, just a DAP.  It was as I was inserting the 2.5mm dc plug into my Sonic Impact t-amp that the HDP started to sizzle.  I am surprised that everything still seems to work after the smoke and the smell, but I definitely don't want to try hooking up the Goldsource again until I understand what happened better.  Not sure how to troubleshoot, though.  

post #4 of 10
Thread Starter 

I received a replacement board for a very reasonable fee (thanks Nuforce!) and when comparing the two, I can't see anything on the old board that would indicate something happened that would generate smoke.  I am baffled.  I saw and smelled smoke, but the unit still works and doesn't look like anything burnt out.  Oh well.  I now have two HDP guts that both work.

 

As a follow up, I tried using the Goldsource to power something else and I believe it killed a small DAC that I had.  There must be something wrong with the power supply.  I have abandoned it and am now building a Sigma 11.


Edited by FraGGleR - 11/9/12 at 11:56am
post #5 of 10

Did you use an ungrounded power cord or outlet?

 

Straight from the manual:

 

"WARNING: Use only grounded AC power cords.
Always immediately disconnect the power to the equipment in the event the device emits an unusual odor
or sound or generates smoke."

 

It also seems like it should have been able to handle the voltage:

 

"Power Requirement: 15V, 1.6A, 100-240VAC"

 

All from:

http://www.nuforce.com/index.php?option=com_k2&view=item&layout=item&id=481&Itemid=248

post #6 of 10
Thread Starter 

The power supply wasn't actually hooked up to the HDP.  I had the HDP hooked up to a T-amp via the RCA outs and actually hooked up the T-amp to the power supply.  The smoke came out of the HDP, so I'm not sure what happened.  T-amp was fine as well.  From a power cord standpoint, yes, it was grounded.  I don't know what is going on inside the power supply.  I checked the voltage and it was dead stable at 13.81.  Now that I think about it, what I didn't do is check the polarity.  I just went off of the colored terminals, assuming that it was wired correctly.  

 

I definitely would like to understand what happened, and am building a Sigma 11 mostly as an learning exercise to better understand power circuits.  The nice upshot is that I have two HDP's now that work.  Just have to figure out a casing solution to the extra board (all the connections are board mount and glued tight).

post #7 of 10
Quote:
Originally Posted by FraGGleR View Post

The power supply wasn't actually hooked up to the HDP.  I had the HDP hooked up to a T-amp via the RCA outs and actually hooked up the T-amp to the power supply.  The smoke came out of the HDP, so I'm not sure what happened.  T-amp was fine as well.  From a power cord standpoint, yes, it was grounded.  I don't know what is going on inside the power supply.  I checked the voltage and it was dead stable at 13.81.  Now that I think about it, what I didn't do is check the polarity.  I just went off of the colored terminals, assuming that it was wired correctly.  

 

I definitely would like to understand what happened, and am building a Sigma 11 mostly as an learning exercise to better understand power circuits.  The nice upshot is that I have two HDP's now that work.  Just have to figure out a casing solution to the extra board (all the connections are board mount and glued tight).

I can't find any listing for the power supply you describe on Amazon.  However, it could be that your incident is similar to the ones that happen with the Cisco switching supply and the Starving Student: it fried several Alien and Bantam DACs over the years, and destroyed a few Gamma 1's, too.  The Cisco switching supply has a floating ground that seems to cause a differential voltage charge to build up on the RCA jacks of the Starving Student.  Connecting a DAC whose DAC chips were not filtered by anything but some output capacitors meant that the transient charge went right through the capacitors and fried the DAC chip.

 

If I'm not mistaken, seems like I was in a discussion thread about the NuForce DACs once and that it had no output capacitors at all.

 

Anyway, it's a thought.

post #8 of 10
Thread Starter 
Quote:
Originally Posted by tomb View Post

I can't find any listing for the power supply you describe on Amazon.  However, it could be that your incident is similar to the ones that happen with the Cisco switching supply and the Starving Student: it fried several Alien and Bantam DACs over the years, and destroyed a few Gamma 1's, too.  The Cisco switching supply has a floating ground that seems to cause a differential voltage charge to build up on the RCA jacks of the Starving Student.  Connecting a DAC whose DAC chips were not filtered by anything but some output capacitors meant that the transient charge went right through the capacitors and fried the DAC chip.

 

If I'm not mistaken, seems like I was in a discussion thread about the NuForce DACs once and that it had no output capacitors at all.

 

Anyway, it's a thought.

Thank you.  This makes a lot of sense (as much as it can for me).  At least it fits the scenario the best.  

 

This is the power supply:  http://www.amazon.com/Goldsource%C2%AE-DF-1721-Regulated-Linear-Supply/dp/B006T3MOLK/ref=sr_1_13?ie=UTF8&qid=1352563596&sr=8-13&keywords=goldsource+power+supply

 

Unfortunately, the manufacturers website is down and I can't find a schematic.  

 

By the way, would a fried capacitor look like it was fried?  I thought due to the smoke, I would have seen something blown up inside the HDP, but I didn't. 

 

And to trouble you further, is there anything relatively simple that I could do to make sure something like this doesn't happen again?  I am assuming the Sigma11 is a very good design and I shouldn't run into a similar problem assuming I don't mess up the build.

post #9 of 10
Quote:
Originally Posted by FraGGleR View Post

Thank you.  This makes a lot of sense (as much as it can for me).  At least it fits the scenario the best.  

 

This is the power supply:  http://www.amazon.com/Goldsource%C2%AE-DF-1721-Regulated-Linear-Supply/dp/B006T3MOLK/ref=sr_1_13?ie=UTF8&qid=1352563596&sr=8-13&keywords=goldsource+power+supply

 

Unfortunately, the manufacturers website is down and I can't find a schematic.  

 

By the way, would a fried capacitor look like it was fried?  I thought due to the smoke, I would have seen something blown up inside the HDP, but I didn't. 

 

And to trouble you further, is there anything relatively simple that I could do to make sure something like this doesn't happen again?  I am assuming the Sigma11 is a very good design and I shouldn't run into a similar problem assuming I don't mess up the build.

I hate to be contrary, but that link took me to a linear regulated (not switching) power supply that appears to be fully grounded.  I don't think what I described could happen with one of those. confused.gif

 

Fried electrolytics are easy to spot: the top is popped (bulging) and there's liquid goo everywhere.  I can't tell you about blown film capacitors - I haven't worked very much with voltages that are high enough to blow a film capacitor.

 

As for the Sigma 11, it's probably best to ask AMB about that.

post #10 of 10
Quote:
Originally Posted by tomb View Post


Fried electrolytics are easy to spot: the top is popped (bulging) and there's liquid goo everywhere.  I can't tell you about blown film capacitors - I haven't worked very much with voltages that are high enough to blow a film capacitor.

I've seen one on an electric fence energiser. Basically had a huge hole blown out the side and there was black dust everywhere, scorch marks on the board, the smoke had made a violent escape.
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