Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: pompeiisneaks on April 04, 2016, 11:50:35 am
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Do you really even need to wire this up? If so, how do you? I was googling and didn't find any information other than people saying the new reissue of some other amps that have it have a switch but it isn't even wired. I searched the forum too and didn't find anything on it.
~Phil
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It originally connected a cap from one side of the power cord to ground. This was for the days of a 2-prong power cord; one setting (likely the one connecting the cap to the neutral) would result in less buzz/hum.
You could use a metal hole plug to cap that opening. Or you could install a switch if you want it to look complete.
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Ok thought so, just wanted to be sure. Thanks :)
~Phil
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Or you could rig it to bleed a wee-little bit of B+ buzz into the audio. Then it "does something".
Joke.
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Lol! I don't want a suck switch :l2:
Phil
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Some of the Fender reissue amps do wire that switch. Others don't. If I had a chassis that had a hole labeled "Ground", I'd probably wire it as a ground switch or at least put a switch in the hole. The cap needs to be a Class Y type. This cap is often referred to as the death cap because if it shorted it would put 120VAC directly on the chassis (your strings!) depending on the position of the switch. I've never heard any names mentioned of someone that died because of a failed death cap. But as soon as you connect the green wire in the power cord to chassis, the cap becomes as safe as any other cap (as long as the house wiring is up to code!)
http://el34world.com/charts/Schematics/files/fender/Fender_59_bassman_manual.pdf (http://el34world.com/charts/Schematics/files/fender/Fender_59_bassman_manual.pdf)
http://el34world.com/charts/Schematics/files/fender/Fender_65_deluxe_reverb_manual.pdf (http://el34world.com/charts/Schematics/files/fender/Fender_65_deluxe_reverb_manual.pdf)
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I suppose if you were very diligent in the separation of all circuit ground from the chassis, you could use that Ground switch as a Ground-Lift switch. That amounts to a switch which either shorts circuit ground to chassis ground ("Ground" position) or un-shorts a network placed between circuit ground & chassis ground ("Lift" position).
There are several circuit ground-to-chassis ground networks which can be used to minimize noise in ground-lift mode. If you choose to go that route, we can point to candidate networks.
It will be difficult to implement a proper ground lift in a tweed-style chassis due to space restrictions.