Problem with Sinus Live SL-1500


2013-12-08 8:27 pm
Hello to all, my problem is that when you turn on the amplifier do not nothing happens but when connect a load (loudspeaker) less than 1.5 ohms, capacitors (-) RAIL are heated in excess. The voltage across the capacitor becomes of the more than 100Vd.c (even up to 125Vdc). The MOSFET output is right. I need help. Thank you.

Perry Babin

Paid Member
2003-11-20 11:01 am
Set the scope to DC coupling, 20v/div and set the timebase to 10us.

Place the probe on the negative rail and adjust the position of the trace so that it aligns to the first major division from the bottom.

Move the probe to the gate of the low-side FET. It should show a rounded square wave that's about 1/2 major division above the line you set the negative rail to. The waveform should go completely to the negative rail point and up approximately 1/2 of one major division. Try this with no input and no speaker load. The rail voltage may remain where it's supposed to be.