LM3886 fuse - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 27th September 2008, 04:12 PM   #1
infobot is offline infobot  United States
diyAudio Member
 
Join Date: Apr 2005
Location: Eastern US
Default LM3886 fuse

Boy, my LM3886 (BrianGT kit). At first fine with 2A fuses. Then started going through them. Tried 3A then started eating those too. 4A maybe not always, 5A seems fine.

Just surprised was able to use 2A for so long.

Amp checks out fine, just current inrush at turn on. Added xformer for dual mono - really started eating fuses. Worked sometimes using 2A in dual mono amazingly. Maybe summer apartment air conditioners or something.

Used 18V + 18V, 250VA Avel Lindberg transformers, US voltage. First one then two for dual mono.
  Reply With Quote
Old 27th September 2008, 04:25 PM   #2
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Hi,
Is the fuse/s on the primary or secondary side ? Are you using anti surge fuses ? Do you mean it blows on switch on or when in use ?
  Reply With Quote
Old 27th September 2008, 04:53 PM   #3
Ted205 is offline Ted205  United Kingdom
diyAudio Member
 
Ted205's Avatar
 
Join Date: Jun 2008
do you switch your source on when the amp is already on?
  Reply With Quote
Old 27th September 2008, 04:54 PM   #4
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Changing to dual mono means that your inrush current has just about doubled. At time 0 the inrush current drawn by a toroid is almost entirely determined by the dcr of the winding so to prevent nuisance blowing you would need double the fuse rating or a time delay fuse.

Toroids have ridiculously high inrush current and it is not unusual to see single transformers of just a couple of hundred VA with up to 6A slow blow fuses..

You need time delay type fuses designed for inductive loads, and a 5A - 6A fuse with your 2 transformers is an acceptable choice - just don't expect it to provide much protection in the event of a component failure. Even better would be a separate fuse for each power transformer - this would provide almost reasonable protection in the event of a malfunction on one channel.
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 27th September 2008, 05:00 PM   #5
Did it Himself
diyAudio Member
 
richie00boy's Avatar
 
Join Date: Nov 2003
Location: Gloucestershire, England, UK
500VA total load, really needs a soft start. Then you can get back to using correctly sized fuses.
__________________
www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more.
  Reply With Quote
Old 27th September 2008, 06:04 PM   #6
infobot is offline infobot  United States
diyAudio Member
 
Join Date: Apr 2005
Location: Eastern US
Default LM3886 fuse

Thanks glad I asked. Will try the separate fuses per side and check into soft start.

Fuses blow only on startup, no problems when in use.
Fuse is on primary side.
Used all time delay (slo blo) fuses.

Switch amp on before source a lot but it varies. Like esp if using another amp then change to gainclone amp.
  Reply With Quote
Old 27th September 2008, 07:36 PM   #7
enzoR is offline enzoR  Netherlands
diyAudio Member
 
Join Date: Mar 2008
I have 2x 330VA avel lindberg's. Turning them on blows my 16A circuit breaker

Use a soft-start circuit!! Much better for your rectifier/capacitors aswell, and you can get by with your 2A fuse again (also safer).

i use this one for mine. sorry that its in dutch, but the schematic is very simple and works well. Another option is this one but it is more complex and not necesarily better. Ofcourse there are other options out there aswell....
  Reply With Quote
Old 28th September 2008, 05:25 PM   #8
infobot is offline infobot  United States
diyAudio Member
 
Join Date: Apr 2005
Location: Eastern US
Default LM3886 fuse

Thanks for the links.
Actually we're 120 volt out here but thanks still helpful.

Anyone thoughts on fusing after primaries? Is it a good idea to put a fuse before the power supply boards and the amp boards?


(i assume audiophile materials fuses if used come quite after a project been proven to be more reliable)
  Reply With Quote
Old 28th September 2008, 05:30 PM   #9
enzoR is offline enzoR  Netherlands
diyAudio Member
 
Join Date: Mar 2008
its best to put the right sized fuse before the primary.
  Reply With Quote
Old 28th September 2008, 05:59 PM   #10
infobot is offline infobot  United States
diyAudio Member
 
Join Date: Apr 2005
Location: Eastern US
Default LM3886 fuse

Makes good sense. Think using separate fuses and adding soft start should help with that one.

Sorry guess what I meant was in addition to before the primary. Heard it mentioned, some folks fused everything, just wondered.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Fuse housing melting but fuse not blowing, ppi amp rawadia Car Audio 21 2nd August 2008 10:39 AM
Why main fuse and not rail fuse? digital desire Solid State 10 3rd December 2006 08:07 PM
amp rating for fuse and fuse holder? riotubes Parts 5 27th August 2006 03:10 AM
Are two separate lm3886 = 2*lm3886 in parallel or bridge mode rs1026 Chip Amps 11 21st October 2004 10:24 AM
fuse Dj BASS AMP Solid State 8 23rd November 2002 04:54 PM


New To Site? Need Help?

All times are GMT. The time now is 12:44 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2