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Old 10th October 2005, 12:23 AM   #1
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Default first amp build... wiring questions

this is my first amp build, and i am using the monoblock kits from antique electronic supply.... instead of following the kit exactly, i am mounting it on an aluminum chassis... im using a front mounted power switch, chassis mounted binding posts, and a detachable power cord...

my first question is how do i hook up the power switch and still use the fuse that is supplied... the kit comes with a switch mounted on the power cord, which i am not using

this is what i have so far

Click the image to open in full size.

is this correct???

this is a huge learning experience for me...... next time ill try point to point
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Old 10th October 2005, 01:17 AM   #2
EC8010 is offline EC8010  United Kingdom
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Fuse first, then it protects you from a fault in the switch. Even better, use an IEC socket with built-in fuse.
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Old 10th October 2005, 09:26 PM   #3
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Quote:
Originally posted by EC8010
Fuse first, then it protects you from a fault in the switch. Even better, use an IEC socket with built-in fuse.
No ...Double pole switch first then fuse.....safety directive....
Why ? if power cord is reversed a double pole switch will avoid the possibility of shock from a damaged fuse or holder from current flowing round other part of live circuit. I now fit double pole switches with a neon inside.

Also. My mains supply is split phase 2x 115V so in practice both power pins are actually live but an electric shock will only be 115V.

richj
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Old 11th October 2005, 01:10 AM   #4
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so the way i have it is fine then????
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Old 11th October 2005, 08:02 AM   #5
EC8010 is offline EC8010  United Kingdom
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Quote:
Originally posted by richwalters
No ...Double pole switch first then fuse.....safety directive....
Why ? if power cord is reversed a double pole switch will avoid the possibility of shock from a damaged fuse or holder from current flowing round other part of live circuit. I now fit double pole switches with a neon inside.
I see the logic, but an IEC lead isn't reversible. Is the plug into the wall outlet reversible? We Brits have non-reversible wall outlets, and we like a fuse in our IEC inlet so that we are protected against any fault, including the switch (there was a thread on here recently discussing a switch that gave a member a shock).
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Old 11th October 2005, 08:47 AM   #6
dhaen is offline dhaen  Europe
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Also normal IEC inlet fuses can't be accessed without first unlpugging the power cord.

If you use an IEC inlet, it's advisable to fit a "boot" over the rear so that the pre-switched live points are covered.
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Old 11th October 2005, 03:50 PM   #7
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im lost......

i will be using an IEC outlet, but it will NOT have a fuse in it.....im using the inline fuse from the kit.....

there will be 3 wires coming off the IEC into the chassis (pos, neg, ground i assume) .... the power will lead down to the power switch which has 2 wires.... where should i put the fuse???

and the ground should just goto the chassis correct??
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Old 11th October 2005, 04:04 PM   #8
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Murphies Law....in the entertainment industry someone in a hurry or in bad light is bound to wire the cord the wrong poles, and this is just what happens.
There is another problem that can arise when the switch is in the wrong place......esp in off line switchmode equipment which uses X & Y input filter. I've seen alot of US power supplies modified for European, and the Y filter cap values unchanged would in practice pass double the current permitted.
For hard wired systems using cable entry and grommet .. the earth wire connection should be the longest within the apparatus compared to the other AC ones, that-it- is- the last wire to detach itself from equipment if some *** trips over the cable and pulls the other AC ones out. The cord grip also comes into the equation but I've mentioned enough.

All of this comes under User safety regulations in various approvals houses....naturally all information is given in good faith.

richj
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Old 11th October 2005, 04:35 PM   #9
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Quote:
Originally posted by jdbrocious
im lost......

i will be using an IEC outlet, but it will NOT have a fuse in it.....im using the inline fuse from the kit.....

there will be 3 wires coming off the IEC into the chassis (pos, neg, ground i assume) .... the power will lead down to the power switch which has 2 wires.... where should i put the fuse???

and the ground should just goto the chassis correct??
I alway's wire my amps with an IEC inlet module (no fuse, I use a separate fuse holder like you).
Black wire (hot), should have the letter "L" on the back of the IEC inlet, goes to fuseholder first, then power switch.
Other side of power switch goes back to power transformer.
White wire (neutral) goes directly to the power transformer.
Green/Yellow wire (ground) goes directly to the chassis right next to the IEC inlet, keep this wire short.

Others may have other methods, but I find this is very common on a lot of shematics I've built (US based).

Glenn
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Old 11th October 2005, 04:39 PM   #10
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OOOPS
I didn't see that you were not in the US, my mistake.
I believe blue is neutral and brown is hot in Europe, although I'm not sure.
Maybe someone can elaborate?
Glenn
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