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