Mamba Monster dead?

Originally Posted by Pdelcast

The ceramics show about .005 ohm or so. The inductor isn't as compact as the capacitors because there isn't any inductors as compact as the capacitors -- not really sure what you mean. The smallest 22uh 4 amp inductors are at least 10mm square.

The FETs are snubbed using an RC snubber -- to prevent ringing.

The component that is failing is the switcher controller -- a National LM3485. National is looking into it with us -- seems the overcurrent circuit is failing internal to the LM3485, and leaving the chip in constant overcurrent state. That's why the output voltage drops to 1.08V - -it's in hiccup overcurrent mode. Replace the LM3485, and all works well again.

Patrick

for the techies
http://www.national.com/pf/LM/LM3485.html

[GriffinRU]

Originally Posted by Pdelcast

The ceramics show about .005 ohm or so. The inductor isn't as compact as the capacitors because there isn't any inductors as compact as the capacitors -- not really sure what you mean. The smallest 22uh 4 amp inductors are at least 10mm square.

The FETs are snubbed using an RC snubber -- to prevent ringing.

The component that is failing is the switcher controller -- a National LM3485. National is looking into it with us -- seems the overcurrent circuit is failing internal to the LM3485, and leaving the chip in constant overcurrent state. That's why the output voltage drops to 1.08V - -it's in hiccup overcurrent mode. Replace the LM3485, and all works well again.

Patrick

Is it possible that having 2 Fet's tripping the overcurrent, meaning your sense resistor (via Fet) readings are not consistent and Isense is way to sensitive from IC to IC? I am assuming that it is 1 fet per IC (6pin, close to inductor).

Yes, 4 amps inductor is hard to find, but I thought that you can get openframe ones and direct solder them to pcb.

[Sparky]

Here are some photos of my Monster
Monster case issue.


Gasket I installed for more clearance


Case mod for air flow without the fan.


Body mod for air flow without the fan. I cut out the front window.

[phatmonk]

Originally Posted by Pdelcast

The ceramics show about .005 ohm or so. The inductor isn't as compact as the capacitors because there isn't any inductors as compact as the capacitors -- not really sure what you mean. The smallest 22uh 4 amp inductors are at least 10mm square.

The FETs are snubbed using an RC snubber -- to prevent ringing.

The component that is failing is the switcher controller -- a National LM3485. National is looking into it with us -- seems the overcurrent circuit is failing internal to the LM3485, and leaving the chip in constant overcurrent state. That's why the output voltage drops to 1.08V - -it's in hiccup overcurrent mode. Replace the LM3485, and all works well again.

Patrick

Thanks for your personal involvement in this issue Patrick.Both of my Monsters have died you guys received one of them last wednesday and no one has called me so I am assuming you ars fixing it.It will be interesting to see how long it will be till I get the first one back.I will be sending the other one in when I get the first defective Monster back.I now have no speedcontrols so pleeeeeeeeeeeeeeeeease fix it soon.

thanks
Will

hey sparky the spot on the case, is that burned? from that component getting that hot? Or is its rubbing? the later seems unlickely, but...........

[Sparky]

The marks are from rubbing.

[e-mike]

this mmm is completely nudeit look like my old mmno fan hole in the case...wow im scared just to toutch mine

[jhautz]

Sparky, I have the same problem with my case rubbing on the board components. Like yours, my fan plug has broken off, and I was showing wear on the black component also. Instead of the gasket to raise the board I actually took a dremel to the inside of the case bottom to remove a little material from the inside of the case to create clearance where those components were rubbing. My first MMM already had the broken fan plug by the time I found the problem. My 2nd MMM is holding up fine without any rubbing or breakage yet. Both fans are dead already though. I just pulled the stock fan out of the case and strapped a 25mm fan over the vent holes in the top of the case and plugged it into the reciever. I was tempted to do what you did and cut the case (only even more so than you did) but I didnt want to have to worry about voiding the warantee with the way these things seem to be dropping like flies. So far so good for me though... I still have 2 out of 2 running fine with the exception of the fans. (knock on wood)

[glassdoctor]

Originally Posted by jhautz

I still have 2 out of 2 running fine with the exception of the fans. (knock on wood)

Oh, sure... now you're in trouble!

[jhautz]

Originally Posted by glassdoctor

Oh, sure... now you're in trouble!

No doubt... I was really hesitant to even post that. Just seemed like bad Juju.

[glassdoctor]

Both of mine are still working too, but I wouldn't actually say it. Opps...

[phatmonk]

Castle sent me someting today via USPS we will see if its my first failed Monster fixed or replaced.I am gonna send the second failed Monster back today.

[RBMike]

Originally Posted by phatmonk

Castle sent me someting today via USPS we will see if its my first failed Monster fixed or replaced.

Same for me, good turn around. I sent mine in last Monday.