Magnat Classic 360 excessive current

Mote

Member
2010-07-06 10:21 am
Estonia
This amp has 4 channels. It uses two D718A outputs for each channel.

When I bridge the amp to 2 channels then it produces audio.
When I connect speaker wires to any channel while the amp is working I get audio out of the channel. After switching amp off and on again it draws excessive current and trips my power supply. With current limiting lamp inline with B+, the lamp glows at maximum brightness and amp does not start to produce audio.

Amp produces positive and negative rail voltage. Voltages on outputs: 0, +21, 0V and -21, 0 -21V. Twisting the transformer does not change a thing. Resistance between GND and RCA shields is 0. Op amps have +12V, -13V supply voltage.

No idea what to check. Help?
 

Mote

Member
2010-07-06 10:21 am
Estonia
I think the amp is OK, although it draws exceptionally high amount of current during startup. I connected speaker to single channel, removed current limiting lamp from B+, and tried to power the amp up. As soon as power supply tripped I switched it back on, so about ten times and then it stayed on. Amp produced loud and clear audio. I will try it out in the car as soon as I get a new head unit and see how it behaves there.