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Author Topic: Old guitar Amp power polarity and live chassis  (Read 14829 times)

Bob Leonard

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BOSTON STRONG........
Proud Vietnam Veteran

I did a gig for Otis Elevator once. Like every job, it had it's ups and downs.

Jeff Bankston

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Re: Old guitar Amp power polarity and live chassis
« Reply #61 on: July 11, 2016, 05:21:41 am »

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« Last Edit: August 09, 2016, 06:18:12 am by Jeff Bankston »
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Stephen Swaffer

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Re: Old guitar Amp power polarity and live chassis
« Reply #62 on: July 13, 2016, 11:20:25 pm »

The reason I'm considering something like the QUBE is that it's UL rated for grounding, and looks like it grounds stuff. I can easily hang a green wire out of a plug I bought at Lowes, but there's going to be some AHJ that questions how you wired it. In this case it should be obvious that the ONLY thing it can connect to is the EGC contact in the NEMA receptacle. Note that one of these QUBE's will feed "grounds" to three different circuits.

Answering another post reminded me I wanted to comment on this.  The QUBE (while apparently a very useful device) does not "ground" anything.  It provides a way to "bond" amplifiers/gear/whatever to the building grounding system. 

On the surface a pendantic observation-but the difference between grounding and bonding is key to understanding what needs to happen for safety sake.  Perhaps a topic for Code Study, if and when we get that off the ground?  (Sorry-that was intentional :)-caught it after I typed it but gonna leave it!)
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Steve Swaffer

Mike Sokol

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Re: Old guitar Amp power polarity and live chassis
« Reply #63 on: July 14, 2016, 06:24:11 am »

On the surface a pendantic observation-but the difference between grounding and bonding is key to understanding what needs to happen for safety sake.

Yes, I'm well aware of the difference. And you'll note that I normally talk about bonding to the EGC (Equipment Grounding Conductor) rather than "the ground". It can get confusing since the word "ground" is used for a lot of different things. However, in the context of guitar amps the common vernacular is to "ground" the amp, or "ground" the musician.
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Mike Sokol
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Jeff Bankston

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Re: Old guitar Amp power polarity and live chassis
« Reply #64 on: August 02, 2016, 11:47:38 pm »

I did a serial number search on my Fender Twin Reverb and its a 1972. Serial number is A44759. Now to find a non master schematic. I took the death cap out. It has a 3 wire cord with the green soldered to the chassis and new Sprauge PS caps. The grill is not the original doesnt fit very well. 4 screws hold it on.
« Last Edit: August 04, 2016, 03:28:10 am by Jeff Bankston »
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