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Old 19th March 2004, 12:54 AM   #1
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Default Voltage When Switch is Off

This is a total newbie question, but...

Today I was rewiring my Gainclone (aka "Ghettclone"-- worst wiring job EVER) when I thought I had blown a crappy Radio Shack switch and it was failing OPEN!

After futher review (and the purchase of a few more switches) I found that the cause is apparently NOT the switch. When I have the switch on, the voltage across the rectifier diodes is about 17.5 (about what it should be), when I turn the switch OFF, the voltage drops BUT DOES NOT GO AWAY!

I have measured the voltage across the rectifiers at anywhere from 2 volts to 10 volts.

I know that this may seem an idealistic newbie vewpoint, but I thought OFF meant OFF! When I unplug the power completely, the voltage drops to zero.

Is it possible that I have not properly grounded the power supply (I'm testing this) or that I there's a cold joint on the wiring for the neutral / return for the AC?

Maybe I'll just take up knitting, like Mrs. Annan.

Please help!

Kofi
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Old 19th March 2004, 12:59 AM   #2
Bryan is offline Bryan  United States
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This may seem like a stupid question, but are you sure your switch is on the live wire of the mains, and not the neutral?

Just a thought???
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Old 19th March 2004, 01:01 AM   #3
tja is offline tja  Netherlands
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Caps?
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Old 19th March 2004, 01:03 AM   #4
Magura is offline Magura  Denmark
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Dosnt it sound more like he is seeing the voltage of the psu caps?? Else he would measure the same voltage all the time if it was the 0 wire he had the switch on??


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Old 19th March 2004, 01:32 AM   #5
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Actually, the answer is no to both questions.

The switch is connected to the live wire and there are no ps caps attached yet. By the way, there are no stupid responses-- only stupid questions, like mine.

After I re-grounded (is this a word?) the power supply, the voltage on the rectifier diodes with the switch OFF is steady at about 2.5 volts. Not enough to kill (probably), but enough to **** me off.

Any other thoughts? I would happily engage in Santaria if I thought it would go away as a result.

Kofi
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Old 19th March 2004, 01:34 AM   #6
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Wow. I've never been censored before. I'll have to bring this up at the next UN poliy meeting.

For those scratching their heads, the four letter word I used is common North American vernacular pertaining to the excretion of liquid from one's engorged bladder.

Kofi
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Old 19th March 2004, 01:56 AM   #7
Magura is offline Magura  Denmark
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Have you measured the potential between zero and ground without the amp connected ??

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Old 19th March 2004, 02:17 AM   #8
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Me thinks Magura has a point - check your voltages - things may be rotten in Denmark!
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Old 19th March 2004, 02:19 AM   #9
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I guess you're talking about measuring the voltage between the neutral plug and the earth ground plug on the AC receptacle?

If so, there's nothing with the ps unplugged, but about 25V AC with the ps plugged in and aobut 47V AC with it plugged in and switched on. No ps caps here and no amp circuit connected-- just the grounded power supply and some moron who put it all together.

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Old 19th March 2004, 02:23 AM   #10
Magura is offline Magura  Denmark
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This requires a picture and a schematic to solve


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