Rm 203 fuse confusion .help required.

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original45
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Rm 203 fuse confusion .help required.

Post by original45 » 02 May 2018, 10:59

I decided to buy a few spare glass fuses for radio gear I have .
But the rm amp has me confused.
All the other glass fast blow fuses are for 12v and say so on the fuse ends.
Now looking at the glass fuse inside the 203 is says 12.5 amp but 220v.

Is this correct or should it be a 12.5amp 12v fuse.

Surely it needs to be 12v , it's not a mains powered 220v unit.
Or am I totally miss reading something here.

Same goes for my 5/7 amp power supply ,what type glass fuse should sit inside the unit on to the board a 2 or 3amp 12v fuse or 2/3amp 220v.

It's got me confused . Help appreciated please.

Thank you again

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Mudslinger
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Re: Rm 203 fuse confusion .help required.

Post by Mudslinger » 02 May 2018, 12:55

Fuses are rated by current not by voltage. As long as the current rating is correct it doesn't matetr if it is a 250V fuse.
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sonoma
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Re: Rm 203 fuse confusion .help required.

Post by sonoma » 02 May 2018, 13:24

agree with mudslinger on the fuse.

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NightProwler
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Re: Rm 203 fuse confusion .help required.

Post by NightProwler » 02 May 2018, 13:41

ConFUSED :lol: Sorry I'll get my coat :)
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prettypolly
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Re: Rm 203 fuse confusion .help required.

Post by prettypolly » 02 May 2018, 18:04

you got conned on the fuse....

original45
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Re: Rm 203 fuse confusion .help required.

Post by original45 » 03 May 2018, 16:19

Lol thanks guys. I learnt something new yet again.
12.5 amp it is.
Thank you again.
If I were to add a external fuse also at battery terminal should I use same size also 12.5 or smaller.

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ch25
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Re: Rm 203 fuse confusion .help required.

Post by ch25 » 03 May 2018, 16:53

1 fuse is enough.
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Kaliphan
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Re: Rm 203 fuse confusion .help required.

Post by Kaliphan » 04 May 2018, 09:40

ch25 wrote:
03 May 2018, 16:53
1 fuse is enough.
It usually is, but it should be close to the battery if possible because a long cable run could short out and catch fire if the existing fuse is right next to the amp or built in to it so a second fuse at the battery terminal isn't a bad idea.

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Re: Rm 203 fuse confusion .help required.

Post by original45 » 04 May 2018, 12:54

From what I had read seemed to echo a fuse close to battery was good practice thank you.
I'm just not sure on a correct fuse amperage.
The unit has the 12,5amp internally so I can assume o my same as battery or would it be ok to use a 8or 10 amp fuse at the battery fuse point.
Or even less maybe ?.
Thank you all for your advices

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ch25
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Re: Rm 203 fuse confusion .help required.

Post by ch25 » 04 May 2018, 14:21

I would bridge the fuse in the amp to minimalize voltage drop and use 12A fuse close to the battery. Remember to use thick positive wire and take negative as close as possible to the amp.
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Kaliphan
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Re: Rm 203 fuse confusion .help required.

Post by Kaliphan » 04 May 2018, 14:29

original45 wrote:
04 May 2018, 12:54
From what I had read seemed to echo a fuse close to battery was good practice thank you.
I'm just not sure on a correct fuse amperage.
The unit has the 12,5amp internally so I can assume o my same as battery or would it be ok to use a 8or 10 amp fuse at the battery fuse point.
Or even less maybe ?.
Thank you all for your advices
If the amp already has a 12.5 amp fuse fitted as original and it's not something someone has bodged in then you can assume it's because the amp can draw something close to 12.5 amps.

Fitting a lower rated fuse isn't a great idea as it will just blow when you drive the amp properly.

Fit a 12.5 amp fuse or something slightly higher (like a 15 Amp one) at the battery post then if there's a short in the power cable it will blow the fuse at the battery and not set the cable on fire.

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Re: Rm 203 fuse confusion .help required.

Post by Kaliphan » 04 May 2018, 14:36

ch25 wrote:
04 May 2018, 14:21
I would bridge the fuse in the amp to minimalize voltage drop and use 12A fuse close to the battery. Remember to use thick positive wire and take negative as close as possible to the amp.
Chris
No, sorry, that's daft, especially if the amp could be removed and used elsewhere where there might not be a battery terminal fuse.

There's also no need to bridge it out because the voltage drop will be tiny, like an eighth of a volt, so there'll be pretty much no measurable benefit to taking the risk by doing it.

original45
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Re: Rm 203 fuse confusion .help required.

Post by original45 » 04 May 2018, 18:05

Thank you both for the advices I appreciate your inputs and have a clearer idea on what I now need to do.
I will take fully on board a short as possible earth and correct fuse size .
Thank

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