Using a value that gives you approximately 1w across the zener will give the tightest regulation but may produce a lot of heat in the area. It will work but may not be optimal. Going higher will produce less heat but will slightly reduce the regulation.
For the most part, audio circuits have a very high power supply rejection ratio so they aren't susceptible to noise from poor regulation.
If the value you posted is for 1w, I'd try a 470 ohm. Make sure that the 15v (or whatever the zener voltage is) remains relatively constant across a wide range of 12v supply voltages and when the amp is driven hard.
If the resistors run hot (but within their power specs), install them with long leads so that they don't do any more damage to the board.
For the most part, audio circuits have a very high power supply rejection ratio so they aren't susceptible to noise from poor regulation.
If the value you posted is for 1w, I'd try a 470 ohm. Make sure that the 15v (or whatever the zener voltage is) remains relatively constant across a wide range of 12v supply voltages and when the amp is driven hard.
If the resistors run hot (but within their power specs), install them with long leads so that they don't do any more damage to the board.
twillar, I have no rail voltage. The amp is in shutdown/protect at the moment. I have 5 volts on pin 4 of my 494 ic. I can ground the pin and the amps comes to life. But I can only grd it for a sec, the amp's current shoots up high. I can pull rectifiers and amp comes on. I then have nice signals on power supply FET's.
The resistors that I pulled have a value of 253 or so. But the bands are red,white,and orange and silver. They must be discolored from the heat they have produced, because that is 29k/10%.
The resistors that I pulled have a value of 253 or so. But the bands are red,white,and orange and silver. They must be discolored from the heat they have produced, because that is 29k/10%.
If you have a good power supply but pulls high with the rectifiers in, pull the outputs and make sure the TIP's are good and leave them out. Perry has the rest covered. When you have your 15v set then you can look for the shorted EF drive transistors with the TIP's out. This is where I love the thermal camera when dealing with the output of AB amps.
This is just what my next logical step would be if I had this on the bench.
This is just what my next logical step would be if I had this on the bench.
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