audiobahn amp

sethro

Member
2005-08-12 11:08 am
I have a audiobahn A2x600hq rack mount amp.A diode Q15 & a resistor r61p smoked.I cant read the colors on the resistor anymore,or all of the numbers on the diode.Ireally injoyed the amp any help would greatly be appreciated.Ican still read irez44n on the diode.thats the only thing i can see wrong in the whole amp.Can anyone tell me if I can replace it with another diode or resistor?:confused: :confused:
 
IRFZ44N is not a diode, it's a MOSFET and it's likely to be part of the power supply. The resistor is probably connected in series with the gate terminal (the leftmost one) of that MOSFET.

There should be two or more banks of MOSFETs with several IRFZ44N in each, and each MOSFET will have its gate resistor, all of the same value (so look at the others and you'll know the value of the smoked one).

However, these MOSFETs tend to fail in groups and sometimes the control circuit that drives its gates also fails, causing the brand new devices you have just replaced to fail again and again.

Note that there are a lot of components that can fail without smoking or showing any visual sign of damage at all, so don't make the usual mistake of just replacing the smoked stuff and connecting the amplifier to a battery without previously checking that everything is right. You'll probably get more smoked stuff if you do so. Test the amplifier with a low current 12V power supply first (and an oscilloscope if available).
 
after you fix the amp, power it up with a small fuse (like 5 amps or less), that way, if it's not fully fixed, the amp would blow it's fuse instead of blowing up again (hopefully).

But the FETs usually blow all at the same time, so it might be wise to test or replace the others, too. if you follow the grid lines, do they go straight to the PWM controller chip, or are there some trasistors (there should be four total) that boost the signal from the controller chip.If it has the driver transistors, these are going to be bog-standard bipolar transistors in a totem-pole configuration. If you have the driver transistors, I recommend checking them for shorts or opens with the diode check function on a multimeter.