I received this amp for repair.
The amp powers up and seems stable and produces audio......however upon opening it there were only 2 p/s fets installed.
I get a square wave on all the gate resistor pads but some have big squares and some have small squares.
I am going to put new p/s fets in and see what happens.
I noticed a spot on the board that is brown from heat behind the pwm board from a component in location QP7 and is marked B631K and there is a resistor inline with it that burned in position RP18. I am not sure of the resistance it should be because I cant identify it.
Anyone have one of these lying around that could help me?
The amp powers up and seems stable and produces audio......however upon opening it there were only 2 p/s fets installed.
I get a square wave on all the gate resistor pads but some have big squares and some have small squares.
I am going to put new p/s fets in and see what happens.
I noticed a spot on the board that is brown from heat behind the pwm board from a component in location QP7 and is marked B631K and there is a resistor inline with it that burned in position RP18. I am not sure of the resistance it should be because I cant identify it.
Anyone have one of these lying around that could help me?
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I have checked the gate drive signal, some of the pads have a nice large square wave, and some of the pads have a nice small square wave. Why is there different sizes in waves between gate pads?
Those 2 resistors appear to be similair circuits but are different color and I believe different values.
Those 2 resistors appear to be similair circuits but are different color and I believe different values.
I installed the remaining 6 p/s fets and I now no longer have a square wave.
The amp powers up and is not in protect. There is a hissing noise from somehwere in the power supply. I viewed the drive circuit through the scope while powering the amp and it starts to go square then loses it.
Anything I am missing?
The amp powers up and is not in protect. There is a hissing noise from somehwere in the power supply. I viewed the drive circuit through the scope while powering the amp and it starts to go square then loses it.
Anything I am missing?
This PWM board uses a KIA494AF controller.
According to the datasheet I looked up it says pin #13 is the output controller, and ouput #1 is pin #8 and output #2 is pin #11.
Is this correct?
So I need to view the signal on pins 8 and 11?
The pin configuration is all mixed up on the data sheet an unlike a TL494C is this also correct?
According to the datasheet I looked up it says pin #13 is the output controller, and ouput #1 is pin #8 and output #2 is pin #11.
Is this correct?
So I need to view the signal on pins 8 and 11?
The pin configuration is all mixed up on the data sheet an unlike a TL494C is this also correct?
Wonder if I could sub the 2SD1898's I have.
Same pin configuration, both npn.
Collector-base current: little lower 100v/vs/120v
Collector-emitter current: little lower 80v/vs/120v
Emitter-base current: same
Collector current: higher
Collector power dissapation: higher
Junction temp: same
What do you think?
Same pin configuration, both npn.
Collector-base current: little lower 100v/vs/120v
Collector-emitter current: little lower 80v/vs/120v
Emitter-base current: same
Collector current: higher
Collector power dissapation: higher
Junction temp: same
What do you think?
OK well they must do alot because if they have failed everything to the 494 is dead. The amp does nothing, totally dead. I am going to remove them and check them out.
Wierd thing is, as soon as I metered pin #8 on the 494 the back of the driver board smoked and everything went dead instantly, no current draw no nothing. Its like somebody just turned a light switch off.
Wierd thing is, as soon as I metered pin #8 on the 494 the back of the driver board smoked and everything went dead instantly, no current draw no nothing. Its like somebody just turned a light switch off.
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