I have a Ashdown MAG300 amp that when hooked to a load draws too much current (perhaps 2-3 amps) upon ramping on a variac. It was reported to be blowing fuses. I've been using a light bulb limiter for testing. Without the LBL the current rises rapidly using the variac, and has a slight constant hum through the speaker. I have checked all the parts on the board, transistors, diodes, resistors, and caps and can't find any suspect parts. There is no DC offset. There is no AC after the main filter Caps.
Would like to know why the excessive current draw with a load and next to nothing without.
The schematic I have is not the correct one and can't seem to locate the correct version.
Also a curious detail: at the line plug into the back incorporates a fuse holder. Printed on the chassis says FUSE RATING 120V T5AL 250V, 230V T3 15AL 250V. It was my understanding that 220V operation usually required a lower rated fuse due to lower current draw with higher voltage?
Would like to know why the excessive current draw with a load and next to nothing without.
The schematic I have is not the correct one and can't seem to locate the correct version.
Also a curious detail: at the line plug into the back incorporates a fuse holder. Printed on the chassis says FUSE RATING 120V T5AL 250V, 230V T3 15AL 250V. It was my understanding that 220V operation usually required a lower rated fuse due to lower current draw with higher voltage?
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