How to Identify and Replace a Blown Fuse




About: My name is Alen and i study electronic engineering. I love to make anything that needs electricity, hack and mod things as well building anything AWESOME...

A fuse is an safety component in electronic and electrical device and it will blow if there is any excessive current.
Short circuit, overloading or device failure are the prime reasons for excessive current.
Putting wrong fuse in device can result in personal injury, fire and increase damage of your broken device.
Never replace a fuse with a higher amperage rating becouse your device can draw more current than its supposed to and whole thing can blow in your face.
Also dont put fuse in parallel or serial
Sometimes you can put smaller current rating fuse if e.g. your device is rated to draw 300 mA but fuse is 500 mA then you can put fuse that is close to 300 mA but not under 300 mA
Fuses are identified with the Amperage (A),Voltage (V) ,Burning speed (Fast-blow,Slow-blow,Time Delay) ,Size and Material (Ceramic,Glass,Plastic,Fiberglass)
There are Axial or Pigtail fuses with wire on the end and they are made for soldering on pcb
Slow blow can handle more current then they are marked for small amount of time and they are marked T and amperage (T2A, T1A, T0,25A) and Fast blow are blowing at marked current , they are marked F (F2A, F1A)
Voltage ratings are not marked in AC or DC
Ceramic fuses are more stable, some ceramic are also sand-filled for extra protection and they can handle higher current rating (more than 15A) a
Glass are see through and they blow faster becouse they dont have sand that will absorb heat
Examples:  Most multimeters use 10A 250V and 250 mA - 500 mA 250V Fast blow fuse 5x20 mm

Step 1: Disconnect Device

In this step you will need to disconnect device that isn't working
It's not so hard you just need to disconnect plug that goes to main socket 
I would also recommend to power off device first

Step 2: Locating Fuse

Fuses are usually at device input so look near power socket
When you pulling fuse out pull it gently so you wont damage fuse or some components

Step 3: Testing Fuse

If you have glass fuse you can easily see if fuse is burned or not
For ceramic types you will need continuity checker/multimeter/ohmmeter
For continuity checker
Put fuse on black and red lead and if you hear beep than your fuse is ok, if theres no beep fuse is burned
For multimeter/ohmmeter
Set multimeter to ohm setting (closest to 1Ω) and put one lead on each end of the fuse and look at the display
If the meter shows a  less than 1Ω then the fuse should be okay, if it show that theres no connection (on my multimeter is 1 on left side) then fuse is burned

Step 4: Buying New Fuse

Check one cap on fuse,PCB or manual for fuse ratings
There should be written something like : T2A250V, F1A250V that's fuse rating
T is for slow blow fuse and F for fast blow fuse
2A or 1A is Amperage rating its usually just number and A
250V is Voltage rating its number and V
And then just measure the size of fuse
In small electrical device is usually 5x20mm
There are 5x20mm, 5x15mm, 6.3x32mm, 3.6x10mm, 5x25mm and 10x38mm



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    9 Discussions


    1 year ago

    Hi I have blown the fuse in my multi meter on the fuse it states 10A 600vac. I have looked and cannot find a 20mm fuse with this rating in the UK so will a 10A 240v be a good substitute

    1 reply

    Reply 1 year ago

    It will be fine as long as you are going to measure things that are less than 240v, since fuse is rated to be safe to 240v, but try to get 600vac one since your multimeter is probably not cheap


    1 year ago

    This is the circuit for my fridge, I think the fuse is blown just by looking, you can zoom to see clearly...

    This is the other side which says Fuse 1 (250V / 9A)

    Please tell me how to properly remove and replace without damaging board or other components,

    Also can I fix it temporarily without fuse, is that too dangerous??


    1 reply

    Reply 1 year ago

    i cant see your picture, but if it looks like one on picture then you just need to swap it out, if its soldered then you will need soldering iron to replace it
    Running it without fuse would mean that in case something happens it would probalby break main fuse in your house (trip automatic fuse), so i wouldnt advise you to do that


    2 years ago

    what if on the outside of the speaker it says "FUSE: TIAL 250V" but once you open it up and look on the board next to the fuses it says "T2AL 250V"? Also, how do you measure any get the right size?

    1 reply

    Reply 2 years ago

    You can use ruler or calipers to measure size, depends on how much speakers are drawing, i would put 1A fuse (if its main 240v, that means 240w so if your speakers are more than that then put 2A), if that blows when you turn volume up, then replace with 2A


    2 years ago

    very good and comprehensive reading;

    and you are still a kid? wow!

    1 reply

    Reply 2 years ago

    I have 18 years now but i was 15 back then :D