Hello, This amplifier (Pioneer A-207R was fully functioning until recently when the fuse blew out of the blue and since after replacing the fuse it pops each time on powering up. Any help will be much appreciated
Replace the fuse, Do not plug in, measure the primary side DC resistance to ensure it hasn't gone 'short' - it is likely you will see a low dc value , might be 15-50ohms depending on VA capacity, but not low single figures. If that is OK, take the lid off, take a look for evidence of arcing ( local discolouration/ browning on the tape) on the transfromer - whether E-I style or toroidal.
However ...failures like this - IME - are most-usually caused by failed rectifer diodes - it only takes one, in a packaged bridge, and you get the mystery instant fuse pop on switch on. So I would start with looking-at, testing or just simply replacing the rectifier diodes - whether discrete, or bridge. Cheap and usually very easy.
Look at the part (s) fitted, and find a replacement equivalent or greater capacity for both PIV and currrent rating, that will fit.
However ...failures like this - IME - are most-usually caused by failed rectifer diodes - it only takes one, in a packaged bridge, and you get the mystery instant fuse pop on switch on. So I would start with looking-at, testing or just simply replacing the rectifier diodes - whether discrete, or bridge. Cheap and usually very easy.
Look at the part (s) fitted, and find a replacement equivalent or greater capacity for both PIV and currrent rating, that will fit.
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