The fuses are the two 30 amp battery fuses. The unit is a Powerware Personal 1000, about eight years old, but in perfect shape. I have new batteries, five six volters, the unit uses 30 volts. From what I've learned, the inverter is a likely suspect. Without a schematic, I'm at a disadvantage. I like the unit because there are no miniature devices on the board, everything is accessable. I'm using it as a learning device, tough as it is. I've checked caps, mosfets, had the transformers off for ringing,the problem is probably hiding in plain sight. If it's a dip, I'm doomed, can't find data sheets or anything on them. Of course, Powerware could care less. (Exide). From what I've learned about inverters, they have two alike caps, about .01 uf. This unit has two alike caps near the dc fuses, but they are about 8700 uf. I'm at a loss, need to find another book on electronics, the ones I have aren't helping. A reccommendation on a really good electronics book is probably what I need best. Any help appreciated.