Check to make sure all your connections are tight and in the right spot. check that your battery terminals are hooked up correctly. check to see if any wires are broken or frayed. Check to make sure your ground cables are tight and not corroded. if that does not fix it you will have to take it into a shop and have them check for the problem. fuses blowing like that are from wires shorting out. Assuming of course this was happening before the new alt.
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