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Post subject: Re: 1975 Silverface Champ upgrades
Posted: Sun Feb 17, 2013 2:01 am
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Rock Star
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Retroverbial wrote:
Bedlam9 wrote:
I just don't get why an amp with a three prong has a death cap.


The larger -- more powerful -- mid-70's silverface amps had a 3-conductor power cord AND the customary rear-panel ground (polarity) switch.

Go figure!

:lol:

Arjay


The only purpose this would serve would be some slight noise filtering:

http://www.bustedgear.com/faq_Amp_shocks.htm

There certainly are better, safer methods.

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Post subject: Re: 1975 Silverface Champ upgrades
Posted: Sun Feb 17, 2013 11:30 am
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Quote:
And you have measured continuity from that chassis solder joint to the ground pin of the plug using an ohm meter? I don't care what wires you see. I want to know what you measured. Its a "yes" or "no" answer.


I gotta invest in a multimeter.


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Post subject: Re: 1975 Silverface Champ upgrades
Posted: Sun Feb 17, 2013 12:06 pm
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I'm gonna see if my neighbor has a multimeter when they get home but do yous think i can get away with playing the amp and not getting electrocuted cause I gotta record some stuff...??


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Post subject: Re: 1975 Silverface Champ upgrades
Posted: Sun Feb 17, 2013 12:08 pm
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Bedlam9 wrote:
Quote:
And you have measured continuity from that chassis solder joint to the ground pin of the plug using an ohm meter? I don't care what wires you see. I want to know what you measured. Its a "yes" or "no" answer.


I gotta invest in a multimeter.


Until you have verified that you have a solid connection between the chassis and the ground pin of the plug, you are not "good to go".

In fact, you are foolish to do anything inside a vacuum tube amp without a multimeter. How do you know that the power supply filter cap(s) are fully discharged before sticking your hands inside the amp? You don't. If you have played the amp recently before doing any work on it, the caps could still be holding a significant charge that, while it may not kill you, will give you a rude shock. I suggest before you do any further work on this amp that you buy a decent DMM immediately. They can be had for under $50. Just make sure the AC and DC rating of the DMM is high enough to accommodate the voltages in your power supply. Most are.

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Post subject: Re: 1975 Silverface Champ upgrades
Posted: Sun Feb 17, 2013 12:10 pm
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Bedlam9 wrote:
I'm gonna see if my neighbor has a multimeter when they get home but do yous think i can get away with playing the amp and not getting electrocuted cause I gotta record some stuff...??


"Do you feel lucky today, punk?"

Dirty Harry

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Post subject: Re: 1975 Silverface Champ upgrades
Posted: Sun Feb 17, 2013 1:33 pm
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bluesky636 wrote:
Bedlam9 wrote:
I'm gonna see if my neighbor has a multimeter when they get home but do yous think i can get away with playing the amp and not getting electrocuted cause I gotta record some stuff...??


"Do you feel lucky today, punk?"

Dirty Harry

haha I will definitely get a Multimeter, I'm not gonna go inside the chasis until I get the readings and check the ground pin.


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Post subject: Re: 1975 Silverface Champ upgrades
Posted: Sun Feb 17, 2013 5:27 pm
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Bedlam9 wrote:
bluesky636 wrote:
Bedlam9 wrote:
I'm gonna see if my neighbor has a multimeter when they get home but do yous think i can get away with playing the amp and not getting electrocuted cause I gotta record some stuff...??


"Do you feel lucky today, punk?"

Dirty Harry

haha I will definitely get a Multimeter, I'm not gonna go inside the chasis until I get the readings and check the ground pin.


Nor should you be playing it, in my opinion, until a solid ground is confirmed. :wink:

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Post subject: Re: 1975 Silverface Champ upgrades
Posted: Sun Feb 17, 2013 5:53 pm
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bluesky636 wrote:
Powdered Toast Man wrote:
Speaker: Weber 8A125


4 ohms.


Weber even offers it in the "Champ correct" 3.2 ohms.

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Post subject: Re: 1975 Silverface Champ upgrades
Posted: Sun Feb 17, 2013 6:00 pm
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I've been using Fluke DVM (or DMM) for YEARS. Hell for decades. But, the ones to get are in the $150-250 range.

A friend bought one of these. And has been satisfied with not only amp use. But, any kind of household or auto needs.


http://www.amazon.com/Klein-Tools-MM200 ... multimeter


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Post subject: Re: 1975 Silverface Champ upgrades
Posted: Sun Feb 17, 2013 11:23 pm
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BMW2002Ti wrote:
I've been using Fluke DVM (or DMM) for YEARS. Hell for decades. But, the ones to get are in the $150-250 range.

A friend bought one of these. And has been satisfied with not only amp use. But, any kind of household or auto needs.


http://www.amazon.com/Klein-Tools-MM200 ... multimeter


Cool, thanks I'll check that out.


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Post subject: Re: 1975 Silverface Champ upgrades
Posted: Sun Feb 17, 2013 11:50 pm
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A good thing to think about is running duble twisted heater lines to the tubes. Really reduces hum, characteristic with single-ended amp.

Need to lift ground solder point from lamp.

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Post subject: Re: 1975 Silverface Champ upgrades
Posted: Mon Feb 18, 2013 5:41 am
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Bedlam9 wrote:
BMW2002Ti wrote:
I've been using Fluke DVM (or DMM) for YEARS. Hell for decades. But, the ones to get are in the $150-250 range.

A friend bought one of these. And has been satisfied with not only amp use. But, any kind of household or auto needs.


http://www.amazon.com/Klein-Tools-MM200 ... multimeter


Cool, thanks I'll check that out.


If you don't want to wait, you can prolly pick on up at Home Depot or Lowes.

Art


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Post subject: Re: 1975 Silverface Champ upgrades
Posted: Mon Feb 18, 2013 7:00 am
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[/quote]Nor should you be playing it, in my opinion, until a solid ground is confirmed. :wink:[/quote]
I got the multimeter... So I'm gonna put the "red thing" on the solder joint and then put the "black thing" on the ground pin and if the multimeter beeps I'm good to go? I'll be back with the results...


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Post subject: Re: 1975 Silverface Champ upgrades
Posted: Mon Feb 18, 2013 7:37 am
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Bedlam9 wrote:
I got the multimeter... So I'm gonna put the "red thing" on the solder joint and then put the "black thing" on the ground pin and if the multimeter beeps I'm good to go? I'll be back with the results...


Yes.

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Post subject: Re: 1975 Silverface Champ upgrades
Posted: Mon Feb 18, 2013 7:53 am
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Ground pin to solder joint beeped.


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