Crunch GP3000

[Perry Babin]

I think that's due to the drive circuit inside the driver IC.

Let's get back to the original problem we were trying to troubleshoot. The voltage on pins 6 and 16 was pulsing. With Q52 out of the circuit, the pulsing stopped.

Was the protect LED flashing with Q52 in the circuit? With it out of the circuit?

 

[mike49504]

Ok when the driverboard is in the amp and Q52 is also in the amp Pads 6,16 pulse.

If i remove Q52 and leave the driverboard in the amp The protection light comes on and stays solid.

With the driverboard and Q52 removed from the circuitboard The amp powers up Power light green and i get no pulsing.

 

[mike49504]

Ok i tryed a different driveboard (audio) and amp still goes into protection So i will try what u said

 

[mike49504]

Ok well now i have -104.5 volts of dc on both output filter inductors before it goes into protection after it goes into protection i get 0 volts.

Is this normal or not?

 

[Perry Babin]

That's not normal.

Is this the original driver board? If not, do you know that it's in good working order?

 

[mike49504]

Its not the orginal This is a new driverboard that i ordered from sundown audio its the same board as the crunch amp takes

 

[mike49504]

Or maybe its not any good Not sure .

With the driverboard removed i get No DC on either Output filter inductor

 

[Perry Babin]

Did the pins on the connector have solder on them or was the gold plating still visible?

 

[mike49504]

All pins have solder on them.

I replaced the ic's again with brand new ones .

As soon as i put the driverboard in straight to protection .

Q52 is removed.

Any ideas on where to start checking again?

 

[Perry Babin]

I was trying to determine if the board was new when installed. A new board would not have had any solder on the pins. I don't know what else to suggest on this one.

 

[mike49504]

I figure it out finally. So if anyone has similar problem with one.

Board location L7905 Its a KIA79L transistor That sits behind the driverboard .


It was defective so i replaced it and amp powers up perfectly now.

I believe its a current sensing transistor .

 

[mike49504]

Now the problem is i have no output .

So i will do some more testing and see what i come up with

 

[Perry Babin]

An L7905 is a -5v regulator.