jl audio 500/1

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this amp is blowing the mosfet transitors q600 to q607
i have 25 k htz at base of mosfets, and voltage looks ok, but every time
I solder 1 set of transistor {2 transistors at a time } they short out.
the one thin I notice is that when I apply power the scope signal
start out of shape, and within 3 seconds signal looks to take shape.
q 608 to q 611 measure ok, this are the driver for the output mosfet,
and r 600 to r607 are 47 ohms, hope to hear from you soon.
thanks in advance.
 
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2 of this resistors measure 49 omhs
and the rest 47 ohms,
seen Im taking measurement from the
driver transistor to the MOSFET gate
pads. I don't think there is any broken.
pads. Again like to mention, that when
I 1st apply power to this unit the scope
wave time start to increse untill the wave
is shape up. is this normal?
 
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I test the amp without the rectifier, and mosfet are no longer geting
destroy, I then place back the rettifier, and remove the audio output
transistor, and no proble. without the audio output transistor in circuit,
I measure the voltage at the rectifier output, and got
28 volts, any sugestion to check at the audio output section?
THANKS IN ADVANCE.
 
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back to this unit, now without any changes, no parts added.
this amp is blowing the power supply output mosfet in about 2 1\2 seconds.
once the rectifier is on the circuit, with or without the audio mosfet.
the power supply mosfet are blowing in about 2 1\2 seconds.
by the way, Im only using 2 power supply mosfet
at a time. let me know if that is ok. thanks in advance.
 
If you're using one FET in each bank of power supply FETs, it should be OK.

You may have an intermittently shorted transformer. To check it, install 8 FETs in the supply and clamp them tightly to the heatsink. Insert a 10 amp fuse in the B+ line feeding the amp and power the amp up. Twist/push/pull on the power transformer to see if it will blow the fuse.
 
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the rectifier was replaced, but no success
every time I connect the center leg of the
rectifier, the power supply mosfet gets hot, and
my power supply amp gage goes up. today I`m going to
try connecting all the power supply mosfet, and clamp
then all together to the heat sink, and use the 10 amp
fuse at the b+ line, and play with the transformer to see
what happens.
 
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put all the power mosfet back, and use one 7 amp
fuse on the b+ line, and the amp is working fine.
Can some one tell me, what it was the I was doing wrong?
thanks for all the help.
by the way, I donated $10.00 the other day, and $10.00 more today,
will this add up? and how do I use or activate my benefits.
thanks again. this site is the best electronic site I ever
visited. keek up the good work.
 
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