Author Topic: Need help finding replacement SMD fuse  (Read 188 times)

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Offline m11k

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Need help finding replacement SMD fuse
« on: August 22, 2020, 08:12:47 pm »
Hi.  Looking for some help finding a suitable replacement.  I blew a fuse on an LCD backlight inverter for a laptop, and need to find a replacement.  I don't really feel comfortable jumping it with a wire.  The markings seems to say "2A 5Z".  It is size 1206.  See attached pics.  If it matters, the voltage on it relative to ground is 20V.  Looking at sites like digikey, I see slow blow, fast blow, or regular?  Will any old 2A fuse do?  I don't need an identical replacement, just something functionally equivalent.  Thanks in advance for any help!
 

Online bdunham7

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Re: Need help finding replacement SMD fuse
« Reply #1 on: August 22, 2020, 09:07:49 pm »
Just ran into this issue with a backlight inverter.  In my case, the fuse used was '2A', but was rated to blow (in 5 seconds) at 2A and had a continuous rating of only 800mA--and the device used 950mA.  I replaced with a 1.25A fuse with a 2.5A 'fusing current', IOW, the current that blows it right away.  The same would likely work for you.  I doubt your backlight actually draws 2 amps or anything close, but I'd jump the fuse with an ammeter and see.  If it is 700-1000mA, the fuse I used will be about right.

I have a few now, I ordered these:

https://www.mouser.com/ProductDetail/652-SF-1206FP125-2

and there's a guy on eBay that sells 3-packs and mails them cheaply.

https://www.ebay.com/itm/1-25A-63V-3pcs-J-Fuse-1206-SMD-SMT-Very-Fast-Acting-Littelfuse/121610040584?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit DMM is good enough for most people.
 

Offline m11k

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Re: Need help finding replacement SMD fuse
« Reply #2 on: August 23, 2020, 01:28:00 am »
Thanks.  That's a good suggestion.  The display backlight specs says power draw is 4.2W typical, so 1.25A at 20V should be more than sufficient rating (but still better than jumping it).  I blew the fuse while testing a borrowed panel which happened to have a bent ground pin that shorted to Vcc on the power connector.  Whoops.
 

Offline aqibi2000

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Re: Need help finding replacement SMD fuse
« Reply #3 on: August 23, 2020, 09:13:25 am »
There are always 2 fuses for this feed if it is LCD/LED laptop

One on the laptop motherboard near the connector and this one you found in the screen driver board

Jumping this will be fine
Tinkerer’
 
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