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-   -   Why does fuse keep blowing (http://www.diyaudio.com/forums/car-audio/105494-why-does-fuse-keep-blowing.html)

imhondamatt 19th July 2007 08:01 AM

Why does fuse keep blowing
 
I have a Hifonics brutus amp. I installed it in multiple cars with no problem. I recently installed into my continental and for some reason i believe there is a internal short. I know for a fact its not external. I have swithced out amps useing the same wires and all is ok. it keeps popping my inline fuse. THe fuses on the amp are fine.Please anyy advise on repair or diag. Would be greatly appreciated.

-thanx in advance.

v-bro 20th July 2007 09:41 PM

Does it pop immediately?

1moreamp 22nd July 2007 05:10 AM

Which Brutus? model number please? Inline fuse size please? And most of all what load are you running the amp at? You have a valid question, but We need more info than you posted to make any quality remote judgment calls :)

imhondamatt 22nd July 2007 07:10 AM

Well
 
The fuse pops almost instantly. Im using a 30 amp just for testing and it still pops. The fuse will pop with no load at all. Its a hifonics brutus 1500 class d mono...I believe..

Thank you for all your advise i really am greatful.

v-bro 22nd July 2007 11:46 AM

I don't know the amp very well, but I suppose it switches Fets. (mostly four pieces on a heatsink).

You can measure them with an ohms meter. From the middle pin to the outer pins you should measure diode-like resistance one way and infinite resistance (no resistance) the other way. When you measure a dead short they're blown...

1moreamp 23rd July 2007 12:01 AM

Re: Well
 
Quote:

Originally posted by imhondamatt
The fuse pops almost instantly. Im using a 30 amp just for testing and it still pops. The fuse will pop with no load at all. Its a hifonics brutus 1500 class d mono...I believe..

Thank you for all your advise i really am greatful.



Power supply is blown and this was blown by the outputs being shorted in the amp. The outputs failed by either too low of a load or the leads to the fet broke off from vibration and that sent them into dead on condition thus blowing the power supply. Common failures only being listed here.
These are sold for like 80 bucks working on e-bay and they seem to all fail the same way. I have only been inside 40 or 50 of them, but when you see the same thing over and over its usually a sign of something.


They are cheap on e-bay buy a new one. As it will most probably need all the power devices replaced and thats a complete job if you do this for a living like I do.

imhondamatt 23rd July 2007 02:35 PM

Thanx
 
Thanx for the answer it has been buggin me for awhile. I looked for a power supply and came up empty handed. Would you be able to help me out to locate one.

Perry Babin 23rd July 2007 04:35 PM

If the amp only blows the fuse AFTER the remote voltage is applied, it's possible that the power supply has survived.

Generally, when there are shorted outputs but a working power supply, the fuse will blow (or the amp will go into protect mode) as the power supply ramps up and excessive current begins to flow through the shorted output transistors.


Since justonemore amp has seen 40+ of these amps, maybe he can tell you if there is a tendancy to blow components on the driver board of the audio section. If so, it may not be worth repairing (unlees the same drver board component fails each time).

1moreamp 23rd July 2007 06:18 PM

I can do one better my friend Perry I have the schematics from Zenon in China where these were made. :) :) :) :)

As for the before and after turn on wire i don't believe I saw that specified by the owner but I might have missed it as it was late last night when i posted.
And you are correct if it is turn related then he might just be able to replace the 4 or 8 bad outputs (IRF3710) in either or both branches of the output stage and get a live one back on stage in his car.
But it will fail again unless he does some modding to the original design that allows the circuit board to flex with vibration and break the FET leads off at the package edge like I see in most of these.
Heck even the rectifier diodes break off to so its definitely a poor mechanical design that kills most of these as the circuitry is quite stout and the safety circuit do seem to work reliably. The newer models have a different assembly and FET mounting trying to solve the problem, but they are failing also from lead frame breakage < just closed one up last week same problem even with vertical mounting of the outputs.

I guess these amps were not meant to be mounted on the bass enclosure and or in the trunk near the bass drivers due to the excessive vibration it imparts on the internals of these amps.:bawling: :bigeyes: :att'n: :whazzat: :whazzat: :whazzat:

Perry Babin 23rd July 2007 07:38 PM

I'd be willing to buy a copy of that schematic.

I'm always interested in buying schematics that are difficult to get.

Tt's amazing how many of these Chinese amps have problems with broken leads. Many times, their solutions don't work and they continue to have problems for several years before they get it right.


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