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presonus firebox died

post #1 of 22
9/16/10 at 2:03am
Thread Starter 

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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post #2 of 22
9/16/10 at 2:53am

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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post #3 of 22
9/16/10 at 9:02am
Thread Starter 

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?

 

 

 
 
IMG_5027.jpg
IMG_5026.jpg
 

 

 

 

 


Edited by zlobby - 9/16/10 at 2:58pm
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post #4 of 22
9/16/10 at 9:17am

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

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post #5 of 22
9/16/10 at 2:12pm
Thread Starter 

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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post #6 of 22
9/16/10 at 2:40pm

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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post #7 of 22
9/16/10 at 2:55pm
Thread Starter 
Quote:
Originally Posted by FallenAngel View Post

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?


Edited by zlobby - 9/16/10 at 2:58pm
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post #8 of 22
9/16/10 at 4:19pm
Quote:
Originally Posted by zlobby View Post




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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post #9 of 22
9/16/10 at 4:29pm
Thread Starter 

fubar.jpg

 

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

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post #10 of 22
9/16/10 at 6:21pm

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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post #11 of 22
9/16/10 at 7:14pm
Thread Starter 

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

 

oLXgW6.jpg

 

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? 


Edited by zlobby - 9/16/10 at 7:16pm
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post #12 of 22
10/16/10 at 4:08am

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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post #13 of 22
10/16/10 at 2:20pm

Quote:
Originally Posted by zlobby View Post

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

 

oLXgW6.jpg

 

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.

 

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:
Originally Posted by Poolboy View Post

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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post #14 of 22
10/17/10 at 11:03am


 

Quote:
Originally Posted by tangent View Post
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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post #15 of 22
10/17/10 at 11:28am

pfft, try soldering 0402 and tell me 0805 is small, my home dac/amp has about 400 0805 and close on 100 0603, but 0402 just aint gonna hapen. 0805 really are quite easily done once you have the technique.

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