I read somewhere on the web that a B+ fuse is practically useless if it's not Fast Blow. I've always used Slow Blow for no other reason other than I just assumed the fast ones would always be popping on start up or stand-by. If it is supposed to be fast, is this also true if using ss diodes?
Also what the correct way to determine size? Same as the PT rating? Double it? Double the total draw at idle? Most 35-50 watters seem to have 500mA even though that's probably 3X the PT.
What is correct type & value for B+ fuses?
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What is correct type & value for B+ fuses?
Last edited by rp on Wed Jul 07, 2010 5:02 am, edited 1 time in total.
Re: What is correct type & value for B+ fuses?
Yeah the B+ fuses are usually slo blo and rated for the output.
The HT or center tap fuses I have seen are fast blo .5amp or 500ma.
You want that one to go fast because it will protect the PT and power tubes better.
The current draw there is usually very little unless there is a fault, then the fuse will blow quickly.
But I have read where they can be rather tricky because if you play with the amp cranked up sometimes the current draw there can raise and blow the fuse.
I've been meaning to experiment with just such a fuse but haven't set aside the time to do it yet.
The HT or center tap fuses I have seen are fast blo .5amp or 500ma.
You want that one to go fast because it will protect the PT and power tubes better.
The current draw there is usually very little unless there is a fault, then the fuse will blow quickly.
But I have read where they can be rather tricky because if you play with the amp cranked up sometimes the current draw there can raise and blow the fuse.
I've been meaning to experiment with just such a fuse but haven't set aside the time to do it yet.
Tom
Don't let that smoke out!
Don't let that smoke out!