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Old 19th July 2007, 09:00 PM   #1
mariusn is offline mariusn  Sweden
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Default Transformer <-> Fuse size question?

My fuses keeps popping, (goes black)

Trying to build the chipamp lm3886amp kit
Using a 500va 2x20vac.

How large should the fuses be, and still be kind of safe?

Have tried 2A 250V and 3.15A 250 they turn black.
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Old 19th July 2007, 09:04 PM   #2
wboyd is offline wboyd  United States
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How are you wiring them?
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Old 19th July 2007, 09:30 PM   #3
mariusn is offline mariusn  Sweden
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Old 19th July 2007, 09:39 PM   #4
Nordic is offline Nordic  South Africa
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Are you useing slowblow fuses? Also it seems like you have fuses on both L and N?
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Old 20th July 2007, 05:27 AM   #5
mariusn is offline mariusn  Sweden
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Quote:
Originally posted by Nordic
[B]Are you useing slowblow fuses? ]
Nope, regulare glass fuses no slowblow

Quote:
Originally posted by Nordic

Also it seems like you have fuses on both L and N?
Yes. the inlet is made that way.




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Old 20th July 2007, 07:29 AM   #6
Nordic is offline Nordic  South Africa
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I would keep a fuse only on L, you are getting into fire and electical hazzard danger area fuseing both... if you want to use 2 fuses, use them after your PSU...

I thought those white thingies were your fuse holders... but it seems to be in the IEC connector drawer... sure it uses 2 fuses?

I'm not saying this is the reason... but you likely have a toroidal transformer.... which causes quite a current inrush on powerup...

get a few slowblow fuses, also called T-fuses they normay have a T before the current rateing on the cap...
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Old 20th July 2007, 08:22 AM   #7
mariusn is offline mariusn  Sweden
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Quote:
Originally posted by Nordic
I would keep a fuse only on L, you are getting into fire and electical hazzard danger area fuseing both... if you want to use 2 fuses, use them after your PSU...

I thought those white thingies were your fuse holders... but it seems to be in the IEC connector drawer... sure it uses 2 fuses?
There are two fuses in the IEC connector drawer (link ), if I remove one of then there will be no connection on the corresponding plug..
So I’m not sure how to use only one fuse?

Would it be a terrible idea to use a 10A as “a no fuse connection”, and one 4A slowblow as the “working fuse”?


Quote:
Originally posted by Nordic
I'm not saying this is the reason... but you likely have a toroidal transformer.... which causes quite a current inrush on powerup...

get a few slowblow fuses, also called T-fuses they normay have a T before the current rateing on the cap... [/B]
I’m on my way to the local electric components pusher.. Whish value slowblow fuses should be sufficient?
500 / 230 = ca 2,2A + the power on inrush??

There is no secret I’m a total DIY newbie..
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Old 20th July 2007, 08:42 AM   #8
Nordic is offline Nordic  South Africa
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I see... about your IEC connector.... you can keep original fuse values, the slow blow ones, blow at the same rateing... but it takes a longer sustained period of exceeding before it blows... I.e. they should survive the inrush.
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Old 20th July 2007, 09:49 AM   #9
Nuuk is offline Nuuk  United Kingdom
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Use a 3.15AT (slow blow) fuse.

Don't some of those fused IEC sockets allow you to house a spare fuse in the drawer as well as the one that is actually functional?
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Old 20th July 2007, 09:52 AM   #10
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all I have seen yet, do have a spare fuse holder
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