Amp Fuse Replacement Wait-time Question - AVS Forum
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post #1 of 15 Old 02-05-2013, 12:13 AM - Thread Starter
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I bought one of those high-end fuses for my amp that keeps blowing its power fuse. Though my manual doesn't say anything about it, I read somewhere about unplugging a generic amp for a while to let the charge dissipate from the capacitor or something before putting in a new fuse. Can someone explain, please?
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post #2 of 15 Old 02-05-2013, 03:22 AM
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When you shut off the receiver/amp, the power supply capacitors are still charged and it takes some time to deplete this charge.
To prevent electrical shock, you should wait some time, to be on the save side. Depending on the circuitry the large power supply capacitors are connected to, this may take some time. To be safe you could / should measure the remaining charge / voltage with a multimeter before you start working inside.

HiEnd fuses ? Sounds like a rip off to me.
If an amp blows its fuses, which are supposed to handle the load the amp was designed for, then something else must be wrong.
Never ever replace it with a stronger fuse or it might damage your amp or burn up your house as a worst case.
Look for the original source of the problem.
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post #3 of 15 Old 02-05-2013, 10:07 AM - Thread Starter
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Thanks. I got the high-end fuse on sale smile.gif The fuses I've been using probably haven't had the right specs (the manual doesn't list the voltage, and local stores only carry one option), and a new AVR somehow has been affecting the line.
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post #4 of 15 Old 02-05-2013, 10:40 AM
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The power supply capacitors will normally have a high-resistance "bleeder" resistor connected to them that discharges them over a period of a minute or so.

They should be fully discharged after one to two minutes.
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post #5 of 15 Old 02-05-2013, 11:08 AM
 
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The fuses I've been using probably haven't had the right specs (the manual doesn't list the voltage,

because it doesn't matter, trip current matters, you did match that didn't you?
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I read somewhere about unplugging a generic amp for a while to let the charge dissipate from the capacitor or something before putting in a new fuse.

That depends on where the fuse is in the circuit. If it's on the AC input you don't need to wait for anything.
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post #6 of 15 Old 02-05-2013, 01:42 PM
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Quote:
Originally Posted by clovenhooves View Post

I bought one of those high-end fuses for my amp that keeps blowing its power fuse. Though my manual doesn't say anything about it, I read somewhere about unplugging a generic amp for a while to let the charge dissipate from the capacitor or something before putting in a new fuse. Can someone explain, please?

The power fuse has no large capacitors associated with it. Just pull the wall plug and replace it!
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post #7 of 15 Old 02-05-2013, 01:57 PM
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Depends, if the fuse can be replaced without opening the case.
If the case has to be opened, than he better waits 'til the power capacitors have discharged in case he accidentally touches something.
Better check twice instead of being hurt.
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post #8 of 15 Old 02-05-2013, 02:00 PM
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well if it is a bulb fuse im thinking of it should state the voltage and amps of it on the fuse itself on the ends that should be silver looking??

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post #9 of 15 Old 02-05-2013, 02:09 PM
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There always is the voltage and current spec. printed or stamped upon the fuse. Strange.
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post #10 of 15 Old 02-05-2013, 04:49 PM - Thread Starter
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Whether or not the voltage really is printed or stamped, at this point the only old fuses I have probably are of the wrong voltage. The fuse can be replaced without opening the case.
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post #11 of 15 Old 02-05-2013, 04:49 PM - Thread Starter
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Whether or not the voltage really is printed or stamped, at this point the only old fuses I have probably are of the wrong voltage. The fuse can be replaced without opening the case.
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post #12 of 15 Old 02-06-2013, 05:11 AM
 
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at this point the only old fuses I have probably are of the wrong voltage.

Why do you think the voltage is important....you haven't mentioned current, despite the suggestion.
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post #13 of 15 Old 02-06-2013, 06:23 AM
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Originally Posted by SAM64 View Post

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at this point the only old fuses I have probably are of the wrong voltage.

Why do you think the voltage is important....you haven't mentioned current, despite the suggestion.

Some fuses are for automotive use and rated at something like 32 volts. Others are for general use and are rated at 250 volts. They will superficially look very similar. Nothing keeps you from mixing and matching them.

If you use a fuse that is rated at too low of a voltage there is some possibility that it will not completely open up when it blows or that it may explode or whatever. In practice none of these things seems to actually happen and it is not unusual to see a low voltage fuse being used on a power line connection.

If one picks up the impression that high end fuses with superior sound quality is a pretty strange concept, then one is perceiving correctly, especially for power line fuses.

Fuses can cause measurable distortion, but this is related to their thermal inertia which is usually pretty much defined by their style and current rating.
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post #14 of 15 Old 02-06-2013, 06:52 AM
 
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The OP bought 'magic' fuses.
They're on the primary side of the power transformer, but he's worried about a capacitor discharging.
The current rating has been mentioned many times, but he's only concerned with voltage.
The voltage rating on a fuse is the maximum voltage it can handle before arcing over.
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post #15 of 15 Old 02-06-2013, 09:45 AM - Thread Starter
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Uh, I already know the current! It's listed in the manual. If you're making fun of me for not understanding capacitors, whatever.
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