Workin On Tube Amps - Safety First!

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mechanicalmastering
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Workin On Tube Amps - Safety First!

Post by mechanicalmastering » Sat Jan 21, 2012 6:14 pm

So, I'm about to make my first attempt at modifying an old tube amp and I want remove the "Death Cap" and make some other modifications,,,, and I am totally freaked out. What are some of the safety steps I need to take inorder to ensure that this doesn't become my LAST tube amp modification?

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Jeff White
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Post by Jeff White » Sat Jan 21, 2012 6:43 pm

Have a professional do it.
I record, mix, and master in my home studio, Ch?teau Blanco, and in various spaces in the Philly area. http://jeffwhiteaudio.com/

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Z-Plane
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Post by Z-Plane » Sat Jan 21, 2012 7:16 pm

1. Keep one hand behind your back
2. Make a cap discharge tool
3. Keep one hand behind your back

I'd be a bit concerned about your "other modifications" idea. The above might get you through popular mods when following detailed instructions, but its not sound advice unless you know exactly what you're doing. What are you doing?

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mechanicalmastering
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Post by mechanicalmastering » Sat Jan 21, 2012 8:57 pm

I'm swapping the 2-prong power cable out for a 3-prong and hopefully doing this:
Image
,,, to give it a safer design as discussed on this:http://messageboard.tapeop.com/viewtopi ... ne+amp+cap thread. I'm no stranger to a soldering iron and I'd like to try my hand at doing simple modifications that could save me money and advance my understanding of various components. Shun me if you like but I don't have a ton of dough to spend on techs and I'm only attempting to seek help and educate myself on how to take the proper precautions to be safe. I have a lot of small vintage tube amps and signal tracers on the way and if this is something that I can handle safely then I'd prefer get my feet wet and accomplish this myself, surely that is an attribute that many of you once possessed at one time or another, please excuse my humble attempt to educate myself.

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RodC
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Post by RodC » Sun Jan 22, 2012 7:25 am

You are always welcome to drop by our place. (as are most TOMB members) and we will help you get started.
'Well, I've been to one world fair, a picnic, and a rodeo, and that's the stupidest thing I ever heard come over a set of earphones'

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Post by Jim Williams » Sun Jan 22, 2012 7:52 am

How Darwinian.
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Gregg Juke
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Post by Gregg Juke » Sun Jan 22, 2012 2:27 pm

...gears-sludz-alert, gear-sludz-alert, weeee-awwwww-weee-awwww...

Dude axed a question...

GJ

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mechanicalmastering
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Post by mechanicalmastering » Tue Jan 24, 2012 9:28 pm

You are always welcome to drop by our place. (as are most TOMB members) and we will help you get started.
Now THAT is some awesome assistance, thanks for such a curious and good-natured offer. Sincerely.

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Post by ckeene » Wed Jan 25, 2012 4:30 am

mechanicalmastering wrote:I'm swapping the 2-prong power cable out for a 3-prong and hopefully doing this:
Image
,,, to give it a safer design as discussed on this:http://messageboard.tapeop.com/viewtopi ... ne+amp+cap thread. I'm no stranger to a soldering iron and I'd like to try my hand at doing simple modifications that could save me money and advance my understanding of various components. Shun me if you like but I don't have a ton of dough to spend on techs and I'm only attempting to seek help and educate myself on how to take the proper precautions to be safe. I have a lot of small vintage tube amps and signal tracers on the way and if this is something that I can handle safely then I'd prefer get my feet wet and accomplish this myself, surely that is an attribute that many of you once possessed at one time or another, please excuse my humble attempt to educate myself.
I've done this on a couple amps. I not a fan of leaving the (now) useless ground switch in the circuit. It's extra solder joints and it's confusing to someone who might need to work on the amp later on. Better still, take the switch out entirely (keep it in the same bag with the 40 year old blue capacitors you replace!) and cap it so no one who uses the amp thinks the switch does anything.

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RodC
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Post by RodC » Wed Jan 25, 2012 4:51 am

ckeene wrote:
mechanicalmastering wrote:I'm swapping the 2-prong power cable out for a 3-prong and hopefully doing this:
Image
,,, to give it a safer design as discussed on this:http://messageboard.tapeop.com/viewtopi ... ne+amp+cap thread. I'm no stranger to a soldering iron and I'd like to try my hand at doing simple modifications that could save me money and advance my understanding of various components. Shun me if you like but I don't have a ton of dough to spend on techs and I'm only attempting to seek help and educate myself on how to take the proper precautions to be safe. I have a lot of small vintage tube amps and signal tracers on the way and if this is something that I can handle safely then I'd prefer get my feet wet and accomplish this myself, surely that is an attribute that many of you once possessed at one time or another, please excuse my humble attempt to educate myself.
I've done this on a couple amps. I not a fan of leaving the (now) useless ground switch in the circuit. It's extra solder joints and it's confusing to someone who might need to work on the amp later on. Better still, take the switch out entirely (keep it in the same bag with the 40 year old blue capacitors you replace!) and cap it so no one who uses the amp thinks the switch does anything.
Naw.. that would make it too easy. Leave it in place, put a label on one side "Suck", mark the other "Suck less"

Everyone can appreciate one more suck knob/switch in the studio.
'Well, I've been to one world fair, a picnic, and a rodeo, and that's the stupidest thing I ever heard come over a set of earphones'

http://www.beyondsanityproductions.com
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ckeene
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Post by ckeene » Wed Jan 25, 2012 5:12 am

:lol:

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Post by crow » Thu Feb 09, 2012 7:38 am

And remember to save the Death Cap for Cutie.

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Gregg Juke
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Post by Gregg Juke » Thu Feb 16, 2012 10:08 am

I wonder if "Cutie" knows who she is?



I guezzzzzzz she'll find out.

GJ

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toine6
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Post by toine6 » Wed Feb 06, 2013 12:23 pm

So I bought this old 1940's wire recorder, the preamp works, but the motor wasn't working, the box had water damage, so I figured it's wire recording days were done, but that I could maybe use it as a tube amp, just to amplify dynamic mics and run synths through etc.

It looks like someone cut the original cord at some point and hand wired and taped another plug and cord to it. If that wasn't dangerous enough, the remaining original cord is all brittle and cracked. SO... I don't really know what I'm doing, but I want to replace the old 2 prong adapter to 3 prong. I figure I can cut off the 2 prong part of the second cord, and tape a third cord with 3 prongs in series, so it will have a 1940's cord, taped to 1970's cord, to 2013 cord with 3 prongs!! JUST KIDDING about that part.

But seriously, I do want to replace the whole cord with a 3 prong cord, then I'd like to build a wooden box and stick the whole tube amp in there. The wire recorder box was made of wood, so I figured it should probably be okay to use wood, but I'm not sure. Also, I don't know how to ground it (staple ground to bottom of wood box???) Or do I need a metal box of some sort?

I'm aware the tube amp could kill me, but I have no wife or kids, and don't like paying taxes to the IRS anyway. I never took a course in electronics and don't understand electronic schematics, but I've done quite a few minor repairs on my equipment.

Can anyone tell me in layman's terms how to replace the 2 prongs cord with a 3 prong, and also if it's okay to mount it into a wood box.

I took some pictures.. If I could get away with just replacing the 2 prong with another 2 prong, and not have a fire hazard/electric death trap on my hand, then that would work too.

http://imageshack.us/a/img715/1232/dscf1689u.jpg

http://imageshack.us/photo/my-images/29/dscf1690o.jpg/

http://imageshack.us/photo/my-images/26 ... 691bn.jpg/

http://imageshack.us/photo/my-images/842/dscf1692d.jpg/

http://imageshack.us/photo/my-images/62/dscf1693w.jpg/

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Post by dfuruta » Wed Feb 06, 2013 1:12 pm

two prong cords are hot and neutral, and so you want to replace those with hot and neutral from your 3 prong cord. the third wire on your 3 prong cord, the safety earth, should be connected by as short a piece of wire as feasible to the metal chassis as solidly as possible (use a spade terminal or something similar attached to a screw with a lock washer & nut).

& don't use a cord sticking out of the box...get an IEC C14 inlet and use a detachable cord.

this thing is already inside a metal case, so if you want to build a wooden box around that, go for it. just make sure you have adequate air-flow. maybe a metal box would cut down on noise, but who cares?

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