rockford 800a2 fried channel help .

ethridgeruby · 22nd July 2005, 07:42 AM

OK... i have a rockford 800a2 one chanel quit working. i opened it up and took my B&K transistor testor and tested that 10 transistors are bad. five IRF640 and five IRF 9640. I replaced them as well as the 10 gate resistors. i was really sure this was all that needed replaced.
well i hooked it up to my aston power supply. all 10 of the transistors i replaced fried within 30 seconds. they got super hot super fast. I Get a voltage reading of around 45+ volts form this speaker output. the working channel I get .3 volts. I am lost now. does anyone have any insight on this.

clem_o · 22nd July 2005, 08:02 AM

Could be several things, but try first looking at the bias circuit, see if anything's open!

After replacing the output MOSFETs again, ensure you put an incandescent lamp IN SERIES with the AC power input of the amplifier first. A good way of doing this is to remove the mains fuse of the ampli and connecting the incandescent bulb across. A 50W or 100W bulb should do, and will make a very nice "unbreakable" fuse that will save your new output transistors from destruction if there is still something amiss in the amp...

Cheers

22nd July 2005, 07:42 AM	#1
ethridgeruby diyAudio Member Join Date: Jul 2005 Location: Freakville, fl	rockford 800a2 fried channel help . OK... i have a rockford 800a2 one chanel quit working. i opened it up and took my B&K transistor testor and tested that 10 transistors are bad. five IRF640 and five IRF 9640. I replaced them as well as the 10 gate resistors. i was really sure this was all that needed replaced. well i hooked it up to my aston power supply. all 10 of the transistors i replaced fried within 30 seconds. they got super hot super fast. I Get a voltage reading of around 45+ volts form this speaker output. the working channel I get .3 volts. I am lost now. does anyone have any insight on this.

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22nd July 2005, 08:02 AM	#2
clem_o diyAudio Member Join Date: Jun 2005 Location: Manila	Could be several things, but try first looking at the bias circuit, see if anything's open! After replacing the output MOSFETs again, ensure you put an incandescent lamp IN SERIES with the AC power input of the amplifier first. A good way of doing this is to remove the mains fuse of the ampli and connecting the incandescent bulb across. A 50W or 100W bulb should do, and will make a very nice "unbreakable" fuse that will save your new output transistors from destruction if there is still something amiss in the amp... Cheers