# presonus firebox died



## zlobby

My presonus firebox was functioning normally up until a few days ago.  I was going to listen to some music, and noticed that the LED in the front was off, so I assumed I must have knocked the firewire cable out.  This was not the case, everything was plugged in fine.  So i unplugged and plugged it back in.  The led flickered a little bit, and then i heard a loud pop, and then death of the unit.  It smelled of smoke too.  Presonus wants to charge me $75 to fix it.  I am pretty handy, and was wondering if anyone here would be able to help me figure out what I might have blown, and not spend $75 to replace this damn thing.


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## xslimmiejimmiex

I have a Firebox too. The only way to know is for you to unscrew the chassis and open it up to see the damage...
   
  Perhaps you weren't using the 12V adapter (its for more stability). However, I hear the adapters can be faulty sometimes, too..
   
  Also, what operating system are you using?
  Desktop or a laptop?
   
  Could've been:
  -failed capacitor
  -burnt resistor
  -burnt switching regulator
   
  If you want to save money, buy the parts...
  If you want to spend more; E-MU 0404 or especially the E-MU 1616


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## zlobby

I wasn't using the AC cord, i always just powered it with the firewire cable.  I use a win 7 desktop.  I am considering buying and emu regardless because it has a better DAC, because my interface serves dual function (recording and dac).  But i would at least like to fix this and resell it to recoup some costs.  
   
  EDIT:
   
  Ok so i opened her up and I found one cap that looks physically damaged.  Also at about 4 o'clock to the cap there is a diode(i think) that has some browning around the solder.  Some of the 1/4" outputs look as if they have been burned and have that rainbowing associated with heating metal.  Aside from the cap thats obviously toast, what are the chances that this took out other parts of the board?  In terms of electrical shock, how much threat does this unit pose at the moment?


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## FallenAngel

Open it up, take photos, post them, look for damage.


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## zlobby

I cant read what it says on the diode that appears fried.  If anyone that has a firebox could tell me what the numbers/letters on that, it would be greatly appreciated.  Presonus wont give me a schematic


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## FallenAngel

That's a capacitor, not diode.  Just cut it off and look for what markings it has on there (or see if there is an identical sized one beside it).


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## zlobby

Quote: 





fallenangel said:


> That's a capacitor, not diode.  Just cut it off and look for what markings it has on there (or see if there is an identical sized one beside it).


 

 Im aware that the cylinder is a cap (33uF 63v), but the rectangular thing adjacent (4 o'clock) to the cap looks fried too.  Thats a SMD right?


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## beerguy0

Quote: 





zlobby said:


> Im aware that the cylinder is a cap (33uF 63v), but the rectangular thing adjacent (4 o'clock) to the cap looks fried too.  Thats a SMD right?


 
  Could be a resistor. Can you get a little closer shot of that part? (Or better focus?) It's hard to tell what it is in the picture, but it looks more like a resistor to me.


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## zlobby

here is the part in question with better focus.  I removed the capacitor already.


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## FallenAngel

Any way to clean the part off a little, there should be some markings on it, kind of looks like a chip resistor.


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## zlobby

It is in fact a resistor.  I wasnt able to see anything after cleaning it off a bit.  After looking around some, I came across this forum, in which a guy had_ almost_ the same problem I have.
   
http://www.prodigy-pro.com/diy/index.php?topic=38350.0
   
  his image of what failed is below
   




   
  He fixed his problem, unfortunately he didnt post the values for the resistor.  It turns out the cap in the bottom left corner of mine failed too, just didnt notice because it didnt explode.  How do I test to see if my switching regulator is fried like his?


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## Poolboy

Hi Zlobby,
   
  I appear to have the exact same problem and I have registered here purely because of it.
   
  I`m a complete noob at electronics so I doubt I could fix the problem myself, particularly soldering in such tiny components. If it helps the Capacitor in question in my unit has the number uF63 v 33.
   
  What is the technical term for the tiny square part?


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## tangent

Quote: 





zlobby said:


> It is in fact a resistor.  I wasnt able to see anything after cleaning it off a bit.  After looking around some, I came across this forum, in which a guy had_ almost_ the same problem I have.
> 
> http://www.prodigy-pro.com/diy/index.php?topic=38350.0
> 
> ...


 
   
  Clockwise, from lower-left, the parts are:
   

 Electrolytic capacitor, 470 μF 10 V
 0805 chip resistor, 10 kΩ
 Electrolytic capacitor, 33 μF 63 V
 LM2586S-ADJ adjustable-voltage switching regulator
   
  There's no way of telling what type of resistor they used just by looking at it.  My guess is 1% 1/8 W thick film, but that's only based on popularity of that resistor type, not on any knowledge of the circuit.  The only circuit knowledge I'll admit to is that it looks like it's just being used as a current limiter in series with the other SMD parts you can see in that loop, so I'd guess that the resistor type isn't critical.
   
  Quote: 





> How do I test to see if my switching regulator is fried like his?


 
   
  Replace the known-damaged parts with good ones, turn it on, and see if they explode again.  If they do, replace the LM2586, too.
  
  It could be that the cap gave up the ghost first, and its sudden absence caused the event that took out everything else.  If so, the fresh cap will keep everything else alive.
   
  It could also be that the regulator died first, and that blew up everything sensitive around it.
   
  Quote: 





poolboy said:


> I doubt I could fix the problem myself, particularly soldering in such tiny components.


 

 0805 is indeed quite small.  I'd put that right on the borderline of DIY hobbyist hand-solderability.  I've done it before.  It's not fun, but with the right technique, you don't even need special tools.  See my soldering videos: Tangent Tutorials.


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## Poolboy

Quote:  





> 0805 is indeed quite small.  I'd put that right on the borderline of DIY hobbyist hand-solderability.  I've done it before.  It's not fun, but with the right technique, you don't even need special tools.  See my soldering videos: Tangent Tutorials.


 

 I could watch your Tutorials until the cows come home but I have little or no soldering experience and there is no way I could solder that tiny resistor in there. I will have to seek out a professional somewhere locally. Thanks for your reply though.
   
  I guess this is the reason Presonus christened it the Firebox...


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## qusp

pfft, try soldering 0402 and tell me 0805 is small, my home dac/amp has about 400 0805 (this may seem ridiculous, but is a rough estimate of all systems, 4 channel balanced dac, USB, fifo buffer, DSP, clock and all digital inputs, something like 35-40 regulators and all control, monitor systems) and close on 100 0603, but 0402 just aint gonna happen. 0805 really are quite easily done once you have the technique.


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## tangent

deleted


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## Hobz

Add me to the list of people that registered here because this exact thing happened to them.  So did any of you guys ever fix your Firebox?


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## zlobby

Quote: 





hobz said:


> Add me to the list of people that registered here because this exact thing happened to them.  So did any of you guys ever fix your Firebox?


 


  I was waiting for a sample to come from national semiconductor and it never came.  I will try to fix it sometime, but i bought a new interface, so i have kinda forgot about the firebox.


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## pablomarc

did anyone get their firebox working again? I have the exact same problem. tried replacing the blown capacitor and it just blew again. power led never came on either...


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## rhythmdevils

I own 2 of these units and they both still work.  One of them was used pretty heavily as a DAC/preamp and was on all the time for at least a few years with no problems.


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## electrobug

Hi
   
  Just managed to get my Presonus working again, after much the same problem as described in this thread. Couldn't get any help from Presonus (I asked 'em....) so for the good of Presonus kind, here are my experiences in a picture:
   

   
  Many thanks to the contributors here, who lead me to believe  I could fix it. 
  Hope this is helpful.
   
  Regards
  Greg


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## jammin Mazio

This is right up my alley. I just had the same issue. Got the Firebox a few years ago (2009-ish). recently, it started getting very noisy. I think I was using only the firewire for power, but not sure. Looked at it eventually, a bit after the noise started, and noticed the power supply connector fell out (maybe when I pulled it out to look at it???). Put it back in and there were more noises. Turned it off (unplugged it). A few days later decided I needed it again and plugged it all back in. POP! Smelled bad too. JUST happened. Going to dig in and find out . . . probably the same thing everyone else found. Sounded and smells like a capacitor. Probably overstressed. Either a too young US engineer designed it, or, more likely, slapped together at some offshore company (will try to hold my tongue here). anyway, more to come...


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## bluessyndicate

...


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## bluessyndicate

electrobug said:


> Hi
> 
> Just managed to get my Presonus working again, after much the same problem as described in this thread. Couldn't get any help from Presonus (I asked 'em....) so for the good of Presonus kind, here are my experiences in a picture:
> 
> ...


 
  Greg;
   
  Thanks so much for your insightful post, as this appears to be the situation I have.
   
  My cap #2 in your diagram likewise exploded and left residue all over.
   
  question....I don't see evidence of #1 or #3 being problematic....would #1 also have shown visible signs of failure?
   
  I don't see any evidence of failure or heat on #1 or #3.
   
  I would particularly like to avoid dealing with #3 since it's SMT which seems like a hassle.
   
  Just wondering if I can get away with simply replacing #2 and hoping for the best.
   
  Any insights?
   
  Thanks!
   
  Scott


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## napes

Hi
   
  Firstly - thanks for posting the pic above - I had 3 popped capacitors and thought I'd have a go!
   
  - Cap 2 in the image above
  - The cap just to the right of it
  - The cap directly to the left of 5 - the ICA-0635
   
  I replaced these then turned the unit on again, and it blew out another cap on the other side of the board - just outside the image - above the 2 blue resistors top left.
 I replaced that one and also capacitor number 1 on the image (for good measure).
   
  Good news is - the unit powers up fine now and syncs OK - tested for about 30 minutes or so, and I'm getting some audio out of the headphone port.
   
  Bad news is - the audio sounds muffled, and as though the signal is repeated about 3 times - like a delay effect.
   
  I've tested on two machines (to be sure it's not a driver or PC issue).
  I've tested the headphones via another sound card - they are working fine.
   
  Does anyone have any ideas? Would particular components failing cause this effect?
   
  Thanks in advance for any advice... I was excited for a  moment thinking it was fixed... so close... 
   
  cheers
   
  Nathan


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## jprusa

Hi All!
  
 Just wanted to thank everyone on this thread especially 'tangent' and Greg as I successfully fixed my FireBox tonight after studying the information here and ordering the parts.
  
 Tangent's online Soldering videos are excellent and should surely be used in electronics classes! I would never have thought I could have soldered that transistor which is extremely small but his video's made it possible.
  
 -James


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## tangent

Hey, thanks James. I'm glad the tutorials were helpful to you.


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## spacelordmother

Hello -- I realize that this is a *very* old post, but I stumbled upon it while looking for information on fixing my own Firebox.  I also see that several of the posters in this thread are still active, so I figured it couldn't hurt to ask.  

I also had an cap explode on me -- wondering if anyone still has their Firebox to take a peek inside, or better pictures to help me identify the cap value?







I know - why bother with an interface this old? It's always worked great for me and I absolutely hate making trash out of potentially useful things. I figure if I try and it doesn't work then no big deal, but at least I tried. 

Thanks one and all!


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## electrobug

spacelordmother said:


> Hello -- I realize that this is a *very* old post, but I stumbled upon it while looking for information on fixing my own Firebox.  I also see that several of the posters in this thread are still active, so I figured it couldn't hurt to ask.
> 
> I also had an cap explode on me -- wondering if anyone still has their Firebox to take a peek inside, or better pictures to help me identify the cap value?
> 
> ...


Here is a photo of mine, which I fixed 8 (yes 8!!) years ago and has been working ever since. I don't use it a lot - I have an RME fireface 400 racked up now - but It does get an outing when I want to record something quickly in another room as opposed to my little studio. Good luck with the repair - like you I will always attempt a repair and I'm very loathe to throw out good stuff! Its great that we live in an age where the internet allows us to help each other and make this possible.
 Best Regards
Greg


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## spacelordmother

Thank you so much, my friend!  I'll make sure to report back.  

Have a great weekend!


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## spacelordmother

The operation was unsuccessful.  Apparently the blown cap was a symptom for another issue because not long after it powered up (and the light was blue!) there was a loud bang and puff of smoke as the replacement cap met its own end.  There was nothing else obviously wrong so I decided it's time to let this thing go   I did salvage a bunch of parts so hopefully in some way its usefulness will endure.  

Thanks again for your help!


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## prietosanti

Hello everybody, I know this is an old post but is still useful for people like me that has a Presounus firebox.
I had the same problem with the exploded CAP and just wonder if anybody knows the value of the SMD shown in the picture below or if there is another value I can use.
I have 1K SMD 0805, 470 0605 but don't know if would fit.

https://postimg.cc/1nCLDfvr

Any help would be much appreciated!
Thanks!!


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## electrobug

Hi prietosanti
I had a look at my old photos, and it looks like that resistor is marked "066h", which would be 66 ohms. I hope this is helpful; good luck with your repair!
Regards
Greg


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## prietosanti

electrobug said:


> Hi prietosanti
> I had a look at my old photos, and it looks like that resistor is marked "066h", which would be 66 ohms. I hope this is helpful; good luck with your repair!
> Regards
> Greg


Hi Greg
Awesome!!  
thank you so much


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