Hello,
I have 6 of these amps and they are all Identical. I am bound and determined to fix at least one of them by myself.
The amp is a power acoustic 620 Plasma sphere
I have 15vdc on the center leg of the power supply (50N06), I have 0v on all legs of the TL494CN. 0V on the output transistors (TIP35/36), and 0V all legs of all 4 of the KIA4558P.
I have 6 of these amps and they are all Identical. I am bound and determined to fix at least one of them by myself.
The amp is a power acoustic 620 Plasma sphere
I have 15vdc on the center leg of the power supply (50N06), I have 0v on all legs of the TL494CN. 0V on the output transistors (TIP35/36), and 0V all legs of all 4 of the KIA4558P.
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I was a little trigger happy on the first post,
It was working for a second, and the green light was on, but not anymore. Now I have no voltage to the TL494, is one of the legs from the TL494 directly attached to the switched power?
I have a 5amp fuse and I am powering up via a larger 8ohm resistor. the resistor is not getting hot at all.
I have 15v at the torrid transformer.
It was working for a second, and the green light was on, but not anymore. Now I have no voltage to the TL494, is one of the legs from the TL494 directly attached to the switched power?
I have a 5amp fuse and I am powering up via a larger 8ohm resistor. the resistor is not getting hot at all.
I have 15v at the torrid transformer.
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Follow the circuit from the remote terminal towards the 494. Many of the power acoustik amps had only a diode between pin 12 of the 494 and the remote terminal.
poking and prodding seems to have yielded some kind of results. The amp came to life and now has output voltage that can drive a speaker. It sounds very scratchy but it could be the test speaker. I will put the amp back together and put it in a car and test it.
The pin 12 is not simply behind a diode. it seems to go to a voltage regulator (TO-220)(Q2)and there seems to be a couple of dividers that make it too difficult to accurately (quickly) draw a diagram.
The pin 12 is not simply behind a diode. it seems to go to a voltage regulator (TO-220)(Q2)and there seems to be a couple of dividers that make it too difficult to accurately (quickly) draw a diagram.
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There is a lot of scratchy on the outputs. I seem to be able to drown them out by turning the volume up and I can get the erratic voltage to increase and decrease with volume or the gain knob on the amp.
is this a capacitor problem?
is this a capacitor problem?
Q2 appears to be the switch that supply B+ to Pin 12 of the 494.
If the transistor is weak the B+ line to Pin 12 of the 494 will become erratic and power to be intermittent. Check the voltage at Q2's middle leg and Pin 12 for a stable 14 volts or better.
If the transistor is weak the B+ line to Pin 12 of the 494 will become erratic and power to be intermittent. Check the voltage at Q2's middle leg and Pin 12 for a stable 14 volts or better.
If I pull all of the pots out and run audio through it, will this be a way to diagnose them?
I will run around with a soldering iron looking for bad connections now.
I will run around with a soldering iron looking for bad connections now.
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