Transformer <-> Fuse size question?

mariusn · 19th July 2007, 10:00 PM

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.

wboyd · 19th July 2007, 10:04 PM

How are you wiring them?

mariusn · 19th July 2007, 10:30 PM

Nordic · 19th July 2007, 10:39 PM

Are you useing slowblow fuses? Also it seems like you have fuses on both L and N?

mariusn · 20th July 2007, 06:27 AM

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.

Nordic · 20th July 2007, 08:29 AM

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...

mariusn · 20th July 2007, 09:22 AM

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..

Nordic · 20th July 2007, 09:42 AM

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.

Nuuk · 20th July 2007, 10:49 AM

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?

Juergen Knoop · 20th July 2007, 10:52 AM

all I have seen yet, do have a spare fuse holder
regards

19th July 2007, 10:00 PM	#1
mariusn diyAudio Member Join Date: Mar 2006 Location: Malmö	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.

19th July 2007, 10:04 PM	#2
wboyd diyAudio Member Join Date: Aug 2004 Location: Louisville, KY	How are you wiring them? __________________ "I am always doing that which I cannot do, in order that I may learn how to do it"

20th July 2007, 10:49 AM	#9
Nuuk diyAudio Member Join Date: Feb 2003 Location: Somerset, SW England	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? __________________ The truth need not be veiled, for it veils itself from the eyes of the ignorant.

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19th July 2007, 10:30 PM	#3
mariusn diyAudio Member Join Date: Mar 2006 Location: Malmö

19th July 2007, 10:39 PM	#4
Nordic diyAudio Member Join Date: Sep 2005	Are you useing slowblow fuses? Also it seems like you have fuses on both L and N?

20th July 2007, 08:29 AM	#6
Nordic diyAudio Member Join Date: Sep 2005	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...

20th July 2007, 09:42 AM	#8
Nordic diyAudio Member Join Date: Sep 2005	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.

20th July 2007, 10:52 AM	#10
Juergen Knoop diyAudio Member Join Date: Jan 2007 Blog Entries: 3	all I have seen yet, do have a spare fuse holder regards

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