pg octane 900.5 repair

If the amp was properly fused, there should have not been any damage.  If you have an Ohm meter and a digital camera,  And can answer some questions, I am sure we can figure out what the problem is.

If polarity was reversed, it would have blown all of the fuses. 

Do not remove the clamps from the heat sink unless we determine it is necessary.  The cleanliness of the bond of the transistors to the heat sink is important.  The less time it spends apart the better off we are.

If it blows the fuse without the remote terminal connected, the problem lies in the power supply area.  If it only blows the fuse when remote power is applied, the problem lies in the output devices.   Look for the large diode to the left of the picture.  There may or may not be one. 

With your meter set to the diode test function, it should be the only setting with a symbol.  It is the symbol for a diode. 

Remove all fuses from the amp, There are 3 legs on each of the power supply transistors.  Place and hold one meter lead to the center leg of the first transistor, now touch the other lead to another leg of the same transistor.  Write down that reading.  Now move the last lead to the other leg ot the transistor.  Write down that reading.  Move to the next transistor.  Repeat.  On either the set of 4 or the set of 6 there will be one or more of them that read very near 0.00  This is the problem set of transistors.  Once you figure out the shorted set, remove the clamp from that set of transistors so we can get the number off of the top of the transistor.   If you can not read the numbers, place your finger in some of the white heat sink grease and rub it onto the top of the transistor.  Wipe most of it off and you will be able to read the number.