Hifonics zues series 1 power supply


2010-08-21 11:09 pm
I have a Hifonics zues that has been in storage foe 15 years. An original Zues with the orange lettering before the roman numerals started (3 digit SN). The power supply whines, the frequency is low enough to hear (from the amp not speakers). I can adjust the power supply on the board to silence the sound at idle, but when a small 20k signal is applied it comes back and then it will disapeer at higher signal levels. Does anyone know the recommend procedure for adjusting the power supply. I am a die hard Hifonics fan and want to keep this dinosaur alive.
Zeus III

This supply used TIP35s as the switching devices and so the switching frequency is about 25KHz.

Check the compensation between pins 2-3 of the TL494, There should be a series R-C combination. Check that the capacitor is OK

Add a resistor of about 22K between pins 2-3.

Try a snubber from TIP35 collector to collector maybe 4.7R 5w in series with a 0.047mfd 250v capacitor.

Since I designed this amplifier almost 26 years ago I do not have schematics any longer.


Steve Mantz
Zed Audio
Zed Audio Corporation