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ivkata 4th November 2012 11:22 PM

Rockford Fosgate punch p500-2 wont power on
this unit was given to me by my boss who said it wont power on anymore.None of the power/outputs appear shorted but the unit shows no sigh of life -no current draw no lights .any tips on where to start on it .the source legs on the psu fets have 12v on them but no gate voltage ,I'm suspecting the pwm is not working corerctly

Perry Babin 5th November 2012 06:12 AM

What is the DC voltage on pins 11, 12 and 13 of the TL494?

ivkata 5th November 2012 12:15 PM


Originally Posted by Perry Babin (
What is the DC voltage on pins 11, 12 and 13 of the TL494?

pin 11 : 11.84v
pin 12 :11.84v
pin 13 : 4.83 v

Perry Babin 5th November 2012 09:28 PM

What's the DC voltage on pins 3, 4 and 10?

If you can get to all of the pins, post the voltage for all pins on the IC.

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:
Pin 15:
Pin 16:

ivkata 5th November 2012 11:37 PM

Pin 1: 0.02
Pin 2: 0.11
Pin 3: 4.78
Pin 4: 0
Pin 5: 0.4
Pin 6: 3.29
Pin 7: 0
Pin 8: 12.44
Pin 9: 0
Pin 10: 0
Pin 11: 12.44
Pin 12: 12.44
Pin 13: 4.80
Pin 14: 4.80
Pin 15: 4.80
Pin 16: 0

Perry Babin 5th November 2012 11:45 PM

It appears that either the timing capacitor has shorted (unlikely) or the 494 has failed. Pin 5 generally reads ~1.5v.

ivkata 6th November 2012 12:10 AM

i double checked and the voltage on pin 5 is 0.4v.Ive never owned a soldering iron that i can use on those finer parts like smd ic .Could u recomment one for the once in the blue moon amp repair guy

Perry Babin 6th November 2012 12:12 AM

You don't need a special soldering iron. What sort of iron have you been using?

ivkata 6th November 2012 12:17 AM

the ones they sell in autozone for 7 bucks .works fine on the older units but the tip is half the size of the ic

Perry Babin 6th November 2012 04:15 AM

The cheapest soldering iron that I'd recommend is a Weller WP35.

If you apply additional solder to both sides of the IC so that all pins are bridged, you can heat one side then the other until you get the solder molten on both sides then you carefully lift the IC. You then carefully desolder the pins and install the new IC. If you have a large tip, it will bridge between pins. After you get all pins soldered, come back and remove enough solder so that not pins are bridged but all are properly soldered down.

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