I got this amp used, had no idea it was not working. Looked brand new but has 2 orange stickers on it that look like the kind that may be used for RMA or repair by Manufacturer's. I figured it was a refurb, Checked the fuses first, both blown, bad sign. Replaced them and hooked amp up to Battery Pos & Neg only to test it, no other wires connected to it, blew fuses instantly! Opened it up to look for obvious short, none. Removed board from heat sink to check further, no damaged parts, no solder joints long enough to touch heatsink. Inspect heatsink for any marks, found only one scrape like mark above the top of one of the larger Transistors but its way too high up to have touched anything, but looks strangely like a shorted scar in the anodized layer, kinda rough but only the size of the top edge of the Transistors metal backing, 1/2" long 1/16" wide.
Another suspicious looking area was just a few inches away, and looked like a slight grey smoke pattern by the rail screw that holds the set of Transistors and a temp sensor onto the heatsink. Nothing appears to have any damage and nothing is shorted,
I inspect the board further under a high powered magnifying glass and bright lights that I have set up to do microchip repairs on comp boards and Video Cards, looked for solder lapping or any other types of possible direct + - shorts. I see nothing and check all Copper runs for deviation, only thing I can see is that the board has a very poor etching job done that shows bubbling in the top layer of the coating. I scraped the areas that had this to see if the copper has shifted any and touched in the tight spots. I found no obvious problems, removed the Diode near the power input and checked it, tested board without it using my Fluke and still dead short! The only possible thing I can think of is that this board may be more than 2 layers of copper and it has a problem with the sandwiched layer?
Anyone else ever have this problem? I'm looking for an answer from someone who has seen and fixed this type of problem I'm not looking for suggestions, if I cannot find a confident answer from a possible fix for this I will be going to the next level.
I have been trying to fix it using a power supply that puts out less current than the fuse ratings of 2x15A. The only problem is the power supply will only power on for a few seconds before it resets and closes its breaker, leaving me no time to check anything while it has voltage on the board.
I don't want to take out each piece and test them 1 by 1 if I can avoid it, the amp is just not worth the time or effort to consider that route, My next step if I have no leads on a fix is to remove the fuses and plug cop[per strips in there, hook in up to my Optima and let it take 850CCA's of 12v power and see what gets hot first! I have temp surface probe but nothing gets hot enough to use it on the low current power. I know that even with the high current applied it may not reveal the culprit, but it also may and that saves me time and effort in this fix. If it fries more parts and still isn't fixed after replacing them, I'll load it into the clay pigeon launcher and see how good it works as a SKEET Target! Then I can give it a true performance rating on 2 sites in 2 categories.