Vintage Fender amp and grounding? Need help!

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Polyglot
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Vintage Fender amp and grounding? Need help!

Post by Polyglot »

So, i have always known, vintage fender amps are revered for their tone and snap, but my brother always said, steer clear of them. Many of lots of hidden issues and not the least of which is grounding. He had mentioned something about 2 or 3 prongs and grounded prongs and the potential to be electrocuted etc etc.

He told me in general just skip the vintage models and youll never have to worry, use only modern amps, and so i have.

But, recently, someone offered me a Fender Vibrolux 1974 Silverface, my question is, how do i know that the wiring is safe and wont put me or my family at risk of electricution. Please pardon my apparent ignorance on the subject, i simply do not have time to study all sorts of schematics to know what is and what is not safe.

So, i am asking for help. Here is his description.

Image[/img][/img][/img]1974 Vibrolux Reverb. Recapped and output transformer replaced by David Allen of Allen Amps in early 2022. Then just serviced last month by our local amp guru Jim Metz. Clean bill of health (happy to share what Jim did). Upgraded to Eminance Legend 10" speakers. Have the original speakers, will include. Installed a 4 ohm passive attenuator by Stami's Customs to keep the sweet spot at any volume. Fastened onto the amp by Velcro, so quick easy removal if desired. A well cared for vintage amp with some modern touches.

Any idea what prongs it has and if they were safe in 1974 Fender Vibrolux? I want it for my Rick 360 so any help appreciated!
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jps
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Re: Vintage Fender amp and grounding? Need help!

Post by jps »

Polyglot wrote: Tue Oct 24, 2023 2:37 pm So, i have always known, vintage fender amps are revered for their tone and snap, but my brother always said, steer clear of them. Many of lots of hidden issues and not the least of which is grounding. He had mentioned something about 2 or 3 prongs and grounded prongs and the potential to be electrocuted etc etc.

He told me in general just skip the vintage models and youll never have to worry, use only modern amps, and so i have.

But, recently, someone offered me a Fender Vibrolux 1974 Silverface, my question is, how do i know that the wiring is safe and wont put me or my family at risk of electricution. Please pardon my apparent ignorance on the subject, i simply do not have time to study all sorts of schematics to know what is and what is not safe.

So, i am asking for help. Here is his description.

Image[/img][/img][/img]1974 Vibrolux Reverb. Recapped and output transformer replaced by David Allen of Allen Amps in early 2022. Then just serviced last month by our local amp guru Jim Metz. Clean bill of health (happy to share what Jim did). Upgraded to Eminance Legend 10" speakers. Have the original speakers, will include. Installed a 4 ohm passive attenuator by Stami's Customs to keep the sweet spot at any volume. Fastened onto the amp by Velcro, so quick easy removal if desired. A well cared for vintage amp with some modern touches.

Any idea what prongs it has and if they were safe in 1974 Fender Vibrolux? I want it for my Rick 360 so any help appreciated!
We need pics of the plug end of the cord, the back of the amp in the area of where the power cord goes into the chassis and, if you can, slide the chassis out enough to photograph the section of the chassis (inside) of the same area (most important, really).
Polyglot
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Re: Vintage Fender amp and grounding? Need help!

Post by Polyglot »

is this enough?
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jps
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Re: Vintage Fender amp and grounding? Need help!

Post by jps »

As best as I can see it does look to have been rewired correctly. Your third photo shows more or less what I'm looking for, but the angle of it cuts off/blocks the wiring at the rear of the chassis where the outlet and power switch is a bit.
Polyglot
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Re: Vintage Fender amp and grounding? Need help!

Post by Polyglot »

Thank you so much. The guy said it came with the three prong back from factory and that fender started doing that in 1970 so its the 60s ones i should worry about.
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soundmasterg
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Re: Vintage Fender amp and grounding? Need help!

Post by soundmasterg »

Any amp can be modified to have proper 3 wire grounding and take out the 'death cap', except the type of amps that are wired directly to the mains with no power transformer such as some Silvertone guitar and amp combinations for example. That isn't to say that all vintage Silvertones are something to steer clear of either....just the ones of any brand from back then that are wired directly to the mains. These type of amps are commonly known as AC/DC amps and those are unsafe and can't easily be modified to be safe. It's not even particularly hard to properly rewire/modify the vintage amps if you know what you are doing when it comes to high voltage electronics. Don't let your brother scare you away from some of this stuff as vintage Fender amps are some of the best ever made. The 74 Vibrolux isn't the best of the vintage Vibroluxes, partially because of the cabinet having a particle board glued in baffle rather than plywood or a screwed in baffle like tweed amps, but it is going to sound great when compared to modern Fender amps, which are made very poorly and don't sound particularly good. I have a friend with a 73 Vibrolux reverb that was popular at a local blues jam when he used to go.

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iiipopes
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Re: Vintage Fender amp and grounding? Need help!

Post by iiipopes »

First, my '79 Vibrolux I used to own already had the 3-prong cord, as the factory converted from 2-prong to 3-prong UL standard in the late '70's. So on every other amplifier I had over time that only had 2-prong outlets I had my tech convert them to 3-prong. the advantage is that after adding the green third ground wire you can set the ground switch simply to the side that has the least noise.

Yes, this is necessary. I have been shocked severely by equipment that had 2-prong plugs accidently flipped, even after I checked them, but between sound check and performance someone tripped over the cord and "thought they would be helpful" by simply plugging it back in (backwards) instead of telling me.
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