Subwoofer fuse question (1 Viewer)

Hi,

The fuse in my Sub blew during a power surge. It is a 3.15AL250v but my wife went to pick up replacement fuses and the ones she got say 125v. Everything else is the same as the one that came out of the sub. When she powers up the sub the fuze immediately blows.

The surge supressor fried (the first big pop we heard) and then I heard a second not so loud pop (the fuse I assume).

I called Radio shack where we bought the fuzes and they said the voltages difference doesn't really matter it is the amps that matter.

I have very little knowledge with fuses so can you experts please confirm what the RS guy said.. Will the correct voltage fuse (250v) make a difference or does my sub have more issues than a blown fuse..

Thanks in advance..

Really, it depends on what system voltage is expected to be carried through the fuse.

When replacing fuses, the amperage should exactly match the specified value - fuses are mostly there to protect against spikes in current/amperage, so you never want to go higher than expected, and going too low may cause unwarranted failures.

As for voltage, the fuse can be rated higher than the expected voltage, but shouldn't be lower. If the 250v fuse was original, you should replace with a 250v or higher fuse.

Exactly...You can't use lower voltage fuses than rated.Go back, if they really don't have any 250(hard to believe that a Radio Shack would be out of 3a 250v fuses)...get some 280.If out of 250 and 280...that location sucks.Oh yeah...pick up anything between 3 to 3.5 amp. Tolerance of equipment means fuses typically blow at 1.5x their rating. So a .5 amp margin is miniscule.

Appreciate all the replies.. Great info..

Just to clarify, if the 125v fuse blows the second power is applied to the sub, it is definately because the fuse is at a lower rated voltage than the one that originally came out of it.

I am concerned that when I put the correct fuse in, it will blow and I believe that would inicate the sub was damaged during the initial power surge that blew the fuse.

Please let me know and Again really appreciate the help here trying to understand/learn this stuff..

TimmyBosko said:

Appreciate all the replies.. Great info..

Just to clarify, if the 125v fuse blows the second power is applied to the sub, it is definately because the fuse is at a lower rated voltage than the one that originally came out of it.

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No, it is not "definitely" because of the voltage mismatch. It may be, but it may not be.

Most of the time, when a fuse blows it's indicative of another problem. Simply replacing the fuse doesn't "solve" the problem, it simply allows the problem to happen again (if there was/is permanent damage somewhere else in the system).

In your case, since the triggering event was a power surge, it is slightly more likely that everything within the sub is fine and the fuse simply did its job in handling the surge, but there's no way to tell. You need to install a correct replacement first.

If the (correct) replacement blows, then you know there's some other problem with the sub.

Gotcha.. thank you all for the help.. Hopefully I will be thumping the house down this weekend

Crap.. I have to wait until Monday or Tuesday for the fuses to arrive... RS doesn't have the 3.5a 250v Slow blow.. Don't think I have ever gone there and not walked out with a fuse I needed.. I looked at the package of the fuses RS sold us and it says "fast acting" but the actual fuse it came with is a slow blow. So wrong voltage and not slow blow..

I have a 2.1 system so for now in the receiver I set the fronts to large, turned on the extra bass. I cranked it and wow I cannot believe how much bass comes out of those little bookshelf speakers.. It's impressive really so that will make doing without the sub for a few days bearable.

We have a standby generator which turns on 10 seconds after commercial power loss and assumes the load 20 seconds after that. The power surge happened during that gap from losing power to gen taking over.

We bought a UPS and everything is plugged into that.. The hope is that when power is lost, the TV, Rcvr, Sub, Blueray and STB will remain on (Battery power) filling the gap from the power loss to generator takeover. The surge supressor fried so I have to asume it was a lemon.

The wife (penny pincher) argued back when she bought me the HT setup we did not need a UPS. After this she suggested I go get one.
She still says we don't need one for the computer room.. Maybe sometime in the not so distant future I will have one there also..

TimmyBosko said:

Crap.. I have to wait until Monday or Tuesday for the fuses to arrive... RS doesn't have the 3.5a 250v Slow blow.. Don't think I have ever gone there and not walked out with a fuse I needed.. I looked at the package of the fuses RS sold us and it says "fast acting" but the actual fuse it came with is a slow blow. So wrong voltage and not slow blow..I have a 2.1 system so for now in the receiver I set the fronts to large, turned on the extra bass. I cranked it and wow I cannot believe how much bass comes out of those little bookshelf speakers.. It's impressive really so that will make doing without the sub for a few days bearable.We have a standby generator which turns on 10 seconds after commercial power loss and assumes the load 20 seconds after that. The power surge happened during that gap from losing power to gen taking over.We bought a UPS and everything is plugged into that.. The hope is that when power is lost, the TV, Rcvr, Sub, Blueray and STB will remain on (Battery power) filling the gap from the power loss to generator takeover. The surge supressor fried so I have to asume it was a lemon. The wife (penny pincher) argued back when she bought me the HT setup we did not need a UPS. After this she suggested I go get one.She still says we don't need one for the computer room.. Maybe sometime in the not so distant future I will have one there also..

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You "did" get one meant for HT* with Pure Sine Wave...?*Lots are usable. HT variety tend to have cooler lights. But most TV and DVR need PSW.

TimmyBosko said:

Gotcha.. thank you all for the help.. Hopefully I will be thumping the house down this weekend

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Most auto parts stores have these fuses,

Tom V. Power Sound Audio

Ty for the tip on the auto parts store to get the replacement fuse for my sub. I have been calling them but some say that the fuse I need (T3.15AL250v) is a 15A fuse and some say it is a 3A fuse. I have no clue.. can someone please breakdown what the T and the 3.15A means. Is this one truly a 15 amp fuse or 3.15.

I am pretty sure the L means slow blow but please correct me if I am wrong..

Thanks in advance..

schan1269 said:

You "did" get one meant for HT* with Pure Sine Wave...?*Lots are usable. HT variety tend to have cooler lights. But most TV and DVR need PSW.

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This is the one we bought: http://www.cyberpowersystems.com/products/ups-systems/retail-products/LX1500G.html

Not really sure what the PSW stuff is.. this one was recommended by a friend at work who has one for his HT system. He said it works fine and has had no issues with it..

TimmyBosko said:

Ty for the tip on the auto parts store to get the replacement fuse for my sub. I have been calling them but some say that the fuse I need (T3.15AL250v) is a 15A fuse and some say it is a 3A fuse. I have no clue.. can someone please breakdown what the T and the 3.15A means. Is this one truly a 15 amp fuse or 3.15.

I am pretty sure the L means slow blow but please correct me if I am wrong..

Thanks in advance..

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Just take the fuse to the local store and match up the markings. 3.15 = 3 amps BTW. A good rule of thump with amps and woofs is to take the amps (x) voltage(110-120v in USA) and that gives you the continuous draw from the wall. Let's say 375 watts. So the amp is probably rated at something between 250-325 watts depending on how efficient it is.

do NOT put a 15amp fuse in there. If there is a short that fuse may last a little longer than it should and cause something else in the amp to "fry".

Tom V.
Power Sound Audio

TimmyBosko said:

This is the one we bought: http://www.cyberpowersystems.com/products/ups-systems/retail-products/LX1500G.html

Not really sure what the PSW stuff is.. this one was recommended by a friend at work who has one for his HT system. He said it works fine and has had no issues with it..

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All modern electronics have built in surge protection. We recommend plugging our products straight into the wall 99% of the time. If someone wants the warm and fuzzies that come with surge protection we tell them to go with a 15 buck single outlet Belkin. Power conditioners tend to cause more harm than good as they can starve power supplies of amperage. If you only have the sub on this, no worries. If you have a lot of other equipment on it too.....

Tom V.
Power Sound Audio

We had a surge suppressor but that was the first thing that fried. We heard 2 pops during the power surge.. the first one was very loud. The second about 3 seconds later was not as loud. I believe the first one was the surge suppressor and the second pop was the sub fuse. Because of that, i do not have any confidence in surge suppressors alone. Appreciate the info on thr fuze also.. kinda of what i thought just wanted to be sure... thanks

TimmyBosko said:

We had a surge suppressor but that was the first thing that fried. We heard 2 pops during the power surge.. the first one was very loud. The second about 3 seconds later was not as loud. I believe the first one was the surge suppressor and the second pop was the sub fuse.Because of that, i do not have any confidence in surge suppressors alone.Appreciate the info on thr fuze also.. kinda of what i thought just wanted to be sure... thanks

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Do you have any idea what caused this surge? This sounds somewhat catastrophic....meaning lightning or a car hitting a nearby utility pole perhaps? Surge protectors should have a sacrificial MOV. Which model surge protector were you using?

Tom V.
Power Sound Audio

Tom Vodhanel said:

Do you have any idea what caused this surge? This sounds somewhat catastrophic....meaning lightning or a car hitting a nearby utility pole perhaps? Surge protectors should have a sacrificial MOV. Which model surge protector were you using?

Tom V.
Power Sound Audio

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This is an interesting read

http://thewirecutter.com/reviews/best-surge-protector/

Tom V.
Power Sound Audio

Tom Vodhanel said:

Do you have any idea what caused this surge? This sounds somewhat catastrophic....meaning lightning or a car hitting a nearby utility pole perhaps? Surge protectors should have a sacrificial MOV. Which model surge protector were you using?

Tom V.
Power Sound Audio

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Yes we lost power when someone hit a telephone pole during a storm. I forget the model number but I am pretty sure it was a rocketfish with multiple outlets, bought at best buy.

There have been times when we lost power and for a few seconds we hear the tv clicking like the power comes back and goes out again. Then if power is not constant/present the generator kicks on and 20 seconds later it assumes the load.

We unplugged the UPS from the wall and the TV, Bray, STB and receiver stayed on. Not even a flicker. Left it unplugged for a minute then plugged it back in.

We went with the UPS to cover the time from initlal power loss to when the generator assumes the load (approx 30 seconds).

My sub is fried. got the correct fuses and it absolutely will not come on. Made sure it was on in the receiver but no joy.. Getting a replacement.

Appreciate all the replies .. definately learned something here and that is exactly what I expected.. Have a great holiday!

TimmyBosko said:

Yes we lost power when someone hit a telephone pole during a storm. I forget the model number but I am pretty sure it was a rocketfish with multiple outlets, bought at best buy.

There have been times when we lost power and for a few seconds we hear the tv clicking like the power comes back and goes out again. Then if power is not constant/present the generator kicks on and 20 seconds later it assumes the load.

We unplugged the UPS from the wall and the TV, Bray, STB and receiver stayed on. Not even a flicker. Left it unplugged for a minute then plugged it back in.

We went with the UPS to cover the time from initlal power loss to when the generator assumes the load (approx 30 seconds).

My sub is fried. got the correct fuses and it absolutely will not come on. Made sure it was on in the receiver but no joy.. Getting a replacement.

Appreciate all the replies .. definately learned something here and that is exactly what I expected.. Have a great holiday!

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Just an idea, if you(or anyone) is looking for the best protection consider a "whole house" surge system installed right at the main fuse box in the home. That combined with a good Earth ground can work very well.

Tom V.
Power Sound Audio

TimmyBosko said:

Appreciate all the replies .. definately learned something here and that is exactly what I expected.. Have a great holiday!

Click to expand...

A few corrections. First, a fuse does not protect any hardware. A fuse blows to disconnect power AFTER damage has occurred. So that the damage does not create a fire. Fuse is for protection of humans, not transistors.Second, the protector did exactly what its manufacturer said it would do. Disconnect protector parts as fast as possible to avert a fire. Often, surges too tiny to overwhelm protection inside electronics can destroy that power strip. That gets a majority to recommend and buy more grossly undersized protectors.Third, a completely different device, also called a surge protector, could have averted that damage. This 'whole house' solution (as others also recommended)must be located when wires enter the building, connect within feet to earth ground, and rated at 50,000 amps so that even direct lightning strikes (ie 20,000 amps) do not damage the protector. The most critical component. for protection is what the protector connects to and what absorbs hundreds of thousands of joules - an earth ground.This superior solution also costs less money - about $1 per protected appliance. Then nobody would have known a surge even existed.Fourth, once a fuse trips, it must be able to block voltage If using a 32 volt (automotive) fuse, then a blown fuse may still conduct 120 volt electricity If the fuse is 125 volts or 250 volts, then it will stop a voltage when it blows.Voltage number defines what it can stop. Amp number defines what current must exceed (massively) to open that fuse.

I was wondering why if the fuse blew, why did the Sub fry. Well that explains it. Always thought the purpose of a fuse was to open when a surge was received by it to prevent damage as well as fires.

Awesome info and appreciate the extensive explaination of all this.