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Hi Everyone, boy this site has been a big help for me to restore this radio. I have all the caps to restore this radio My question is, I understand that it is a good idea to put a "safety cap" in place of one of the regular caps. Can someone tell me what cap that is. I have a couple .01 safety caps that I got extra on another radiio project. I have the shcematic all I need is what number cap it is. Also is a .0012 okay to replace the .0015 cap. thats the only one I could find that was close.
Thank you in advance
Bob J.
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Bob,
Your safety caps will replace the capacitors that your line cord connects to, I believe that is item 63.
In most cases a .0012 instead of a .0015 would be close enough.
Steve
M R Radios C M Tubes
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Hi Steve thank you for your reply. Though I am somewhat confused. # 63 is the line filter condensor, black box held in with one screw with 4 leads, 1 leg of power cord lead and one green wire together green goes to switch. And other leg of power cord goes with white wire to power transformer. THan of course it has black lead that is ground for the transformer. Do I replace this box with safety cap totaly or is it somehow connected in conjucntion with it. If it replaces this filter do I just connect each end of safety cap to each two wires and leave ground as is and leave box in place. I think I might have just answered my own question. Am I on the right track? I think what threw me is this cap being different the the round paper cap.
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Ohhhh, is it you use "two safety" caps one to each set of wires and other ends to ground!!??
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Yes, one goes from each side of the AC line to chassis ground. Its probably easier to just gut the original bakelite cap and place the new caps inside.
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Thanks Exray
What does the safety cap do over a regular cap? Because if it connects to power cord lead, and lead to on off switch on one end of the cap. and the other end of cap to ground. Than It doesn't have the ability to break the circuit because the two leads would still be directly connected. Or am I missing the point of a safety cap.
thanks
Bob
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Safety caps are designed to fail open. Normal caps may fail open...or fail shorted. Here is where the safety factor comes in. If your cap shorts out, one side of the line is going to be connected to the chassis through the shorted cap, creating a dangerous situation. Now, if the cap fails open, that side of the line will still be isolated from ground because of the now-open cap.
--
Ron Ramirez
Ferdinand IN
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The name "safety cap" is misleading. Actually only one vendor I know of uses that term but it has entered the lexicon.
It doesn't add any safety to the user per se. The safe aspect is like Ron describes, means that it fails open and is flameproof. If you're familiar with some of the older AC bypass caps like the bumblebee types they had a nasty habit of overheating and exploding - sometimes spraying bits of foil all over the chassis.
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Ohhhhh I get it now! Wow your never to old to learn from others. I Love restoring these old radio's, But I want to be safe. My next question is I have a model BK 700 tube tester I tested all tubes but it doesn't have a socket for the # 41 tube. can anyone recommend a tube tester I could use for that. I have looked on ebay and they have alot of testers but I don't know which ones can test those large 6 prong tubes. At this point I just hope those are both good in this radio as I have no way to test them. So would like to get one that can test these any suggestions?
Thank You
Bob
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Well you could always buy an old Eico 625, or if you want to upgrad, youi could buy a Hickok. Mine is a model 539.
Then again, your 41 tube ie electrically almost identical to the 6K6, so if you had an octal plug (as in salvaged from an octal tube dud, a six prong femail socket, and the pinouts (use nostalgia air on he web or any tube manual,) You could make an adapter. This would also work for measuring a 42 tube using 6F6 settings, and maybe others.
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Thanks at least I have an ides on what I would look for.
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exray Wrote:The name "safety cap" is misleading. Actually only one vendor I know of uses that term but it has entered the lexicon.
It doesn't add any safety to the user per se. The safe aspect is like Ron describes, means that it fails open and is flameproof. If you're familiar with some of the older AC bypass caps like the bumblebee types they had a nasty habit of overheating and exploding - sometimes spraying bits of foil all over the chassis.
Actually, there is somewhat of a safety issue. When a line filter capacitor fails shorted, you could have a hot chassis, depending upon which way the non polarized plug is plugged into the wall.
Steve
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Steve Davis Wrote:exray Wrote:The name "safety cap" is misleading. Actually only one vendor I know of uses that term but it has entered the lexicon.
It doesn't add any safety to the user per se. The safe aspect is like Ron describes, means that it fails open and is flameproof. If you're familiar with some of the older AC bypass caps like the bumblebee types they had a nasty habit of overheating and exploding - sometimes spraying bits of foil all over the chassis.
Actually, there is somewhat of a safety issue. When a line filter capacitor fails shorted, you could have a hot chassis, depending upon which way the non polarized plug is plugged into the wall.
Steve
True, but there's an implication that has grown feet that the application of the "safety cap" makes an old radio "shock-proof".
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[/quote]True, but there's an implication that has grown feet that the application of the "safety cap" makes an old radio "shock-proof".[/quote]
Bill, you are absolutely correct. If someone dosen't believe it, they should try standing barefoot on a concrete floor and touch the chassis while it is plugged in. 
Steve
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I have added a GND to my radio (well, a 3-prong cord, chassis being grounded)
does that make my chassis shock-proof?
I also added a fuse, does it render the safety cap superfluous?
-Mars
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