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Topic: Ground Lift Switch |
Jeremy Threlfall
From:
now in Western Australia
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Posted 7 May 2009 9:58 pm |
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Does anyone know fur sure which way (to the left or to the right) the ground lift switch on a Brownface Vibrasonic (1961) goes?
Or is there a way for me to work it out?
The amp is a US 110V version, powered from my 240V (australian) mains via a 240/110 step-down transformer
noisy ole thing that transformer is, I can tell you (I reckon it is of 1961 vintage too) |
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Jim Sliff
From:
Lawndale California, USA
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Posted 8 May 2009 5:17 am
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It is NOT a "lift" switch, and you would NEVER want to lift the ground on an amp - it makes YOU the path to ground!
If you have the original 2-wire cord the switch reverses the polarity, and there's no particular "right" position - it depends on where you are playing and the polarity of the wiring (many older building have the AC polarity...yes, AC power DOES have polarity...reversed.
But - if it DOES have a 2-prong cord it needs to be replaced with a far safer grounded cord, completely bypassing the switch. The switches and the so-called "death cap" are deadly. Some people put 3-wire cords on amps and leave the switch and cap functional, the worst of all possible combinations.
You will not hurt the vintage value by replacing it.
_________________
No chops, but great tone
1930's/40's Rickenbacher/Rickenbacker 6&8 string lap steels
1921 Weissenborn Style 2; Hilo&Schireson hollownecks
Appalachian, Regal & Dobro squarenecks
1959 Fender 400 9+2 B6;1960's Fender 800 3+3+2; 1948 Fender Dual-8 Professional |
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Jeremy Threlfall
From:
now in Western Australia
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Posted 14 May 2009 3:50 am
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Thanks, Jim
I will get my amp tech guy to look at it, and I will pass your advice on to him.
It is a two prong plug (an American amp) which I am using with a 240/110 step down transformer (which came with the amp) and which I guess was manufactured in '61 too - it weighs 7kg and is a noisy b*gger. |
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Danny Hullihen
From:
Harrison, Michigan
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Posted 18 May 2009 1:23 am
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| Jim. Could you post a photo of where the "death cap" is located please? I would like to check this out on my tube amps to see if it has been eliminated. |
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Jim Sliff
From:
Lawndale California, USA
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Posted 20 May 2009 8:20 pm
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They are in different places in every amp, but it WILL be connected to the ground switch. Install a 3-prong cord, bypass the whole ground switch circuit and yank the cap.
_________________
No chops, but great tone
1930's/40's Rickenbacher/Rickenbacker 6&8 string lap steels
1921 Weissenborn Style 2; Hilo&Schireson hollownecks
Appalachian, Regal & Dobro squarenecks
1959 Fender 400 9+2 B6;1960's Fender 800 3+3+2; 1948 Fender Dual-8 Professional |
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Jeremy Threlfall
From:
now in Western Australia
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Jim Sliff
From:
Lawndale California, USA
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Posted 21 May 2009 5:50 am
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That IS typical - but sometimes you find weird things like the fuse in front of the switch, the cap wired correctly but mounted in a different location - that's why a photo does not necessarily help (it might with your amp, but could confuse someone with a different type who only reads part of the thread - that's why I hesitate to post pics of safety-related items that are not consistent.
Your tech should know about the cap, amp polarity and the mandatory need for a 3-prong cord (save the old one for vintage freaks if you ever sell it) - no top-level tech would have to be told where the cap is or would leave a two-prong plug on the amp unless specifically told to - he should be advising you of safety needs, and if that's not happening you need a new tech immediately.
_________________
No chops, but great tone
1930's/40's Rickenbacher/Rickenbacker 6&8 string lap steels
1921 Weissenborn Style 2; Hilo&Schireson hollownecks
Appalachian, Regal & Dobro squarenecks
1959 Fender 400 9+2 B6;1960's Fender 800 3+3+2; 1948 Fender Dual-8 Professional |
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