1987 GN fuse blows & my motor dies out when i hit the brake peddle

[will72rupp1]

i am thinking its a short in my power master some where, i bought it brand new & it work fine for a year or two with no problems at all, but now when i get a few miles away from home i hit the brake peddle to stop & a fuse blows on my fuse panel & it kills the dash & the motor & it won't start, it all dies out, no life at all.. it has the right amp fuse, just keeps blowing it..

i am hoping to convert to vacuum brakes & this fixes this problem..

anyone else here had this happen???????????? what could it be?????????????

ill have to check on it, but i think its the power master fuse, but its a 20 amp fuse, & when it blows i loose it all..