M
Mike Wilson
Guest
Hi all
I decided to repost the problem that I'm having with my amp as it hasn't
been fixed yet.
I have a Kenwood KA-3500 amp, the woofers would pulse when the volume was
set to low (1 or 2)
If the volume is turned up to say 4, the problem goes away. Took the amp
apart, the two large power supply capacitors (42V 6800uF) were defective.
Replaced the two caps, turned the amp on and blew the fuse. I double checked
to make sure the caps were installed correctly, double checked to make sure
no bits of solder or wire fell onto the power board. Replaced the fuse,
turned her back on, the pulsing speaker problem is gone; however I have a
new problem. When the amp is turned on, the speakers extend to their full
length of excursion and stay there. There is a slight hum from the speakers,
then it fades until you can barely hear it. The heat sink gets quite hot,
very uncomfortable to the touch. So, of course I turned her off right away.
Am I right to think I blew one or more of the output transistors mounted on
the heat sink? Would it be a good test to unsolder, the transistors, one at
a time to find out which one is causing the problem? One thing I did try,
is test the output voltage of each transistor. I don't know how to reference
each transistor, so I'll say from left to right when looking at the amp from
the front. #1 transistor is 46.6v #2 transistor is 23.3v #3
transistor is .47v #4 transistor is 0.0v (no milliamps) Can you give me
a idea as to what would be cause this?
Thanks in advance : )
Mike
I decided to repost the problem that I'm having with my amp as it hasn't
been fixed yet.
I have a Kenwood KA-3500 amp, the woofers would pulse when the volume was
set to low (1 or 2)
If the volume is turned up to say 4, the problem goes away. Took the amp
apart, the two large power supply capacitors (42V 6800uF) were defective.
Replaced the two caps, turned the amp on and blew the fuse. I double checked
to make sure the caps were installed correctly, double checked to make sure
no bits of solder or wire fell onto the power board. Replaced the fuse,
turned her back on, the pulsing speaker problem is gone; however I have a
new problem. When the amp is turned on, the speakers extend to their full
length of excursion and stay there. There is a slight hum from the speakers,
then it fades until you can barely hear it. The heat sink gets quite hot,
very uncomfortable to the touch. So, of course I turned her off right away.
Am I right to think I blew one or more of the output transistors mounted on
the heat sink? Would it be a good test to unsolder, the transistors, one at
a time to find out which one is causing the problem? One thing I did try,
is test the output voltage of each transistor. I don't know how to reference
each transistor, so I'll say from left to right when looking at the amp from
the front. #1 transistor is 46.6v #2 transistor is 23.3v #3
transistor is .47v #4 transistor is 0.0v (no milliamps) Can you give me
a idea as to what would be cause this?
Thanks in advance : )
Mike