punch 600a4

[ian33]

This amp came in with two burn ch.All output transistors and some emmiter resistor was bad in these two ch.I unsolder all outputs and emmiters on these two ch.This amp still will not power up,i think it is going into protect.I pull the center legs of the rectifers off the board and got 41 volts on them but the power light is still off.If the drivers on the two burn ch are bad will it cause that?Any idea what is causing this amp not to power up?

[fcruz]

What is your email address to send you to the scheme

[ian33]

ranks33@hotmail.com



thanks

[Perry Babin]

Most Rockford amps drive the power LED from the regulated 15v supply. The 15v supply typically gets its power from the rectifiers. If the rectifiers are out of the circuit, the LED can't light up.

When you say it won't power up, does it drag the voltage from the power supply down or does it simply refuse to produce any rail voltage?

[ian33]

with the rectifier in ciruit it has rail voltage for about 3 seconds.During that 3 seconds the light is on.I have a light blup limmiter on the power line it does not light so it is not drawing to much current.

[Perry Babin]

Post the DC voltage on all pins of the LM339 after rail voltage is lost.

Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 9:
Pin 10:
Pin 11:
Pin 12:
Pin 13:
Pin 14:

[ian33]

I resolder the middle leg of the rectifiers back on the board and now the amp stays power on.I think somthing is about to fail.It has both +&- rail voltage.


LM339

Pin 1: 2.l
Pin 2: 4.7
Pin 3: 13.1
Pin 4: 0
Pin 5: 2.4
Pin 6: 4.8
Pin 7: 4.7
Pin 8: 3.2
Pin 9: 4.8
Pin 10: 4.8
Pin 11: 5.1 plusin to 6.8
Pin 12: 0
Pin 13: 4.3
Pin 14: 4.3

[Perry Babin]

Recheck 1, 6 and 7. They're critical. Also, if you have a scope, look at the voltage on those pins to confirm that they're straight DC and not pulsing DC.

[ian33]

pin1: plusing from 0 to 12 volts
pin6:4.88
pin7: plusing from 4 to 5 volts

This amp is not powering up without a current limmiter.

[Perry Babin]

Try powering the amp up with the B+ terminal limited but the remote terminal connected directly to the 12v power supply.