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Post by Johnkenn on Dec 15, 2017 21:03:25 GMT -6
My Upton PS want turn on. Pulled out the fuse in the PS and it’s blown. Thought I got the right .5A 250V fuse, but it’s the “fast acting” and not the “slow blow.” With the fast acting, it was also dead as a door nail. Wouldn’t I at least blow that one if it was working? I tried a different iec. Different power plug. Can not having the slow blow do that?
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ericn
Temp
Balance Engineer
Posts: 14,940 
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Post by ericn on Dec 15, 2017 22:41:36 GMT -6
My Upton PS want turn on. Pulled out the fuse in the PS and it’s blown. Thought I got the right .5A 250V fuse, but it’s the “fast acting” and not the “slow blow.” With the fast acting, it was also dead as a door nail. Wouldn’t I at least blow that one if it was working? I tried a different iec. Different power plug. Can not having the slow blow do that? A regular will go faster than a slow blow, You want the slow blow, the idea being the high current draw at turn on won't blow the fuse, and still offer protection during regular use! .5 amp 250v should be easy to find at any hardware store! |
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Post by mulmany on Dec 16, 2017 15:13:52 GMT -6
You really need a slow blow if that's what it calls for. If it's a torroid transformer in the PSU they draw a lot of current at startup before stabilizing.
I had a big issue finding slow blows for the last PSU I built locally, ended up buying a bunch online.
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Post by johneppstein on Dec 16, 2017 23:39:06 GMT -6
My Upton PS want turn on. Pulled out the fuse in the PS and it’s blown. Thought I got the right .5A 250V fuse, but it’s the “fast acting” and not the “slow blow.” With the fast acting, it was also dead as a door nail. Wouldn’t I at least blow that one if it was working? I tried a different iec. Different power plug. Can not having the slow blow do that? With much, if not most gear the inrush current when it's turned on is significantly greater than the quiescent current, and the current used when it is in full bore operation. The reason is the need to charge up power supply capacitors and that some electronic devices draw more current as they warm up, especially, but not necessarily limited to, tube gear. The usual reason for using a slow blow fuse is to deal with this surge. |
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Post by Johnkenn on Dec 17, 2017 8:10:55 GMT -6
Got it working. Thanks for the help!
So...after I got the slow blow fuse, I put it in. Still nothing. Pull it out, and realize I’ve been putting it in the wrong little slot the whole damn time. Doh. I wonder if the second little a lot in the tray is to keep a spare?
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Post by adamjbrass on Dec 17, 2017 12:30:08 GMT -6
haha, yup spare slot
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ericn
Temp
Balance Engineer
Posts: 14,940
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Post by ericn on Dec 17, 2017 22:05:30 GMT -6
Got it working. Thanks for the help! So...after I got the slow blow fuse, I put it in. Still nothing. Pull it out, and realize I’ve been putting it in the wrong little slot the whole damn time. Doh. I wonder if the second little a lot in the tray is to keep a spare? Takes a big man to admit to his moments of brilliant Homer Simpson like behavior!😎 |
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