I have these drivers ; www.easy-cnc.com * Your best option in driver boards for CNC machines

I have used it dozens of times without problems. Now the X and Y axis fuses keep blowing as soon as the PSU is switched on. I have tried disconnecting the pc input and motor outputs and then switching on power. The same two fuses blow instantly. I can find no connection problems. I am assuming two of the optocouplers or IC drivers has burnt out (which can be replaced) although I do not know where to buy replacements.