Help me ID this component

MWink

Diamond Member
Oct 9, 1999
3,642
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I have an old APC Back-UPS 1250 that I'm pretty sure would work except that one small component has been removed from the PCB. It looks like it would be fairly easy to replace but I'm not sure what it is. Luckly I have another identical UPS that does have the component so I took a picture of it. I would greatly appreciate it if someone could tell me exactly what this component is and where I might be able to buy one (maybe Radio Shack or Mouser?).

Here is the picture It is the component between the red wire and the marking "F3". As far as I can tell the markings are as follows:

bei (or 1) 5A
MQ 125V


Whatever it is I'm guessing it's rated 125V 5A, I just don't know what it is. Any help would be appreciated.
 

stevty2889

Diamond Member
Dec 13, 2003
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It appears to be a fuse of some sort, but I'm not 100% sure. F# is usualy used to indicate a fuse, and the markings on it are consistant with how a fuse would be rated.
 

nineball9

Senior member
Aug 10, 2003
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It's a 5 amp , 125 volt fuse made by BelFuse.
Try google for a fuse xref for an "MQ" series replacement.
 

MWink

Diamond Member
Oct 9, 1999
3,642
1
76
Yeah that's what I originally thought but I've never seen a fuse that looked like that before. Now I just have to find somewhere to buy one. Thanks for the help.
 

LordMorpheus

Diamond Member
Aug 14, 2002
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Originally posted by: keeleysam
just solder the points together

it'll work, but you risk destroying the UPS if something goes wrong . . . .

but as its currently not working I don't see why that would be a problem.
 

Auric

Diamond Member
Oct 11, 1999
9,591
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Originally posted by: keeleysam
just solder the points together

I am having visions of an old fusebox in your home jammed with pennies.
 

nineball9

Senior member
Aug 10, 2003
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The Bel Fuse MQ series is a "quick acting micro fuse" according to Bel's web site. The MQ series crossreference to the Littelfuse 251 or 252 series. The 252 series is a radial fuse; the 251 series is the same design but with axial leads.

The Bel Fuse and Littelfuse radial lead fuses are very close in size, so you could go with the 252 series radial lead.
Mouser part number, 5A 125V Littelfuse 252 series: 576-0252005.M

Might be easier to bend the leads yourself - in this case get an axial lead fuse.
Mouser part number, 5A 125V Littelfuse 251 series: 576-0251005.M

I copied these part numbers from Mouser's Feb - Apr 2005 printed catalog. You might want to check Mouser's online site to ensure I can type!

Moreover, they are under a buck each, so you might want to order a couple; if you fry a fuse, you'll have to troubleshoot the circuitry, find the faulty component(s) and replace them and try another fuse.

If you have any desire to repair your unit, do not just jumper the old leads unless you have a variac and even then use some sort of fuse. Simply jumpering the leads is done by those with little or no knowledge of electronics or troubleshooting techniques ... the device may actually work fine. In a few years or so the circuit board could develop a short (silicon semiconductors almost always short when they fail). Should a small fire or smoke damage occur as a result, a jumpered lead will void any fire insurance you have on your home.

Good luck!
 

MWink

Diamond Member
Oct 9, 1999
3,642
1
76
Originally posted by: nineball9
The Bel Fuse MQ series is a "quick acting micro fuse" according to Bel's web site. The MQ series crossreference to the Littelfuse 251 or 252 series. The 252 series is a radial fuse; the 251 series is the same design but with axial leads.

The Bel Fuse and Littelfuse radial lead fuses are very close in size, so you could go with the 252 series radial lead.
Mouser part number, 5A 125V Littelfuse 252 series: 576-0252005.M

Might be easier to bend the leads yourself - in this case get an axial lead fuse.
Mouser part number, 5A 125V Littelfuse 251 series: 576-0251005.M

I copied these part numbers from Mouser's Feb - Apr 2005 printed catalog. You might want to check Mouser's online site to ensure I can type!

Moreover, they are under a buck each, so you might want to order a couple; if you fry a fuse, you'll have to troubleshoot the circuitry, find the faulty component(s) and replace them and try another fuse.

If you have any desire to repair your unit, do not just jumper the old leads unless you have a variac and even then use some sort of fuse. Simply jumpering the leads is done by those with little or no knowledge of electronics or troubleshooting techniques ... the device may actually work fine. In a few years or so the circuit board could develop a short (silicon semiconductors almost always short when they fail). Should a small fire or smoke damage occur as a result, a jumpered lead will void any fire insurance you have on your home.

Good luck!


Thanks for all the help. I ordered the Radial fuse as the Axial is no longer stocked according to their website.

Yeah I wouldn't dare jumping it, especially in a UPS. I've already fried a couple UPS's even with all their fuses. :Q