🚀 go-pugleaf

dshipley@cs.umr.edu (Dan Shipley) writes:
> 
> I just got a car audio amplifier from Coustic.  In the manual, it says it  
> uses hex-FET's and NOT to turn the amplifier on if there is no load on the  
> outputs.
> 
> I don't know anything about hex-FET's, but it seems unusual that an infinite  
> output impedance would cause damage to a transistor.  However, I'm always  
> learning just how much I don't know, so if someone could enlighten me in the  
> ways of hex-FET's or why this might cause damage, I'd be grateful.
> 

Where are the HEXFETs used?  They could be in the DC-DC converter
or the audio amplifier section.

If they are in the audio section, your amplifier has an oscillation 
problem at light loads and uses the speaker and wiring as an aid 
to stability (sorta like a crutch).  
If they are in the DC-DC converter, and it is not regulated, the drain
voltages would soar to damaging levels with no load.  Just a guess, as
I don't know much about the Coustic amps.  (I thought they just made
decks and crossovers...)

Have fun!
 -- Louis
--
Louis Bertrand   *   Lynden, Ontario, Canada   *   (416) 648-8066
Signal Path Designs (Analog - Digital - Audio - Embedded uCs)
louis@SignalPath.on.ca (new -- may not work yet)
louis%tronix@maccs.dcss.mcmaster.ca (old -- still works fine)