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PostPosted: 26 Jan 2010, 20:50 
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Hi Reed, the purpose of a Dim bulb tester is to check for shorts in a device without cooking it - kinda like a continuity tester, but under the actual load..

Here is another video on the Dim Bulb Tester


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PostPosted: 28 Jan 2010, 23:16 
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Joined: 14 Oct 2008, 17:35
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Try it without the tubes, then try it with the tubes. If there is a real problem the bulb will stay brightly lit continuosly, if not try some crappy speakers and see if you get any audio out of it. If you get any clear undistorted audio, then it is most likely working. If it is stereo, it might be a good idea to check one channel at a time, just leave the tubes out of that channel not being tested. ;)

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PostPosted: 26 Sep 2013, 20:48 
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Joined: 02 Sep 2008, 14:34
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Location: Rochester, NY
This is the one I use. I like it based on small size and the ability to from Test to Live with the throw of a switch.
Attachment:
Light Bulb test set duplex outlet.pdf

Very handy to for me.


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PostPosted: 24 Oct 2013, 12:06 
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hey guys
the dim bulb tester is in essence a"manually" selectable current limiter. as in the wattage of the lamp determines the limit.
if the use of this device isn't apparent to you i advise any and everyone to do a little more research.
sometimes i think schematics for "devices" should come with some application or"use of" notes.
in crazzyabttubes case with his ea3 the conditions he described would have me checking for leaky cap's in the bias stage and checking my ouput tubes for grid leaks along with checking bias voltage.
does anyone know why?
or better yet explain why i would checked these thing based on the conditions described?


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PostPosted: 24 Oct 2013, 18:00 
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There is a potential problem with testing things without the tubes in place. If there is a solid state power supply and all the filter caps are not rated for the full B+ voltage you can cook them. Often a cap will tolerate a voltage well above its rated one, but if you use a tester like shown and keep it on for any length of time you might run into problems. The bulb might not indicate a problem and the caps can cook. I prefer to use a variac to start up new projects that have problems. This is only after the first time I power something up. To do the first power up I attach loads as needed (resistors on the outputs if a power amp) and ground inputs and follow the procedures in the write up at the beginning of the tube forum. If the fuse blows, (or any of the other odd things happen, like smoke, fire, sparks, etc) then I go to the variac and slowly raise the voltage. I may be different from the typical diyer, but with careful assembly I seldom have something not work on the first try. I am a very careful builder and I'm sure this helps. I also as you all might suspect have a huge supply of replacement parts.

Good listening
Bruce

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PostPosted: 24 Oct 2013, 21:28 
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gofar99
the dim bulb tester by virtue of what it is and does will not harm the device under test and will give an immediate indication of cooked cap's.
in the case of dialing back the voltage on a variac your proportionally limiting current as long as the resistance remains the same but in the case of a hard short what's limiting the current plowing through through your variac (hopefully a dim bulb tester with a carefully chosen lamp value)
in the case of testing a tube chassis unloaded causing cap's to die because of a lack of loads would make me really wonder about it's design.
i have heard about guitar players mod'ing their amps by dropping in a solid state rectifier in place of a tube rectifier and popping filter cap's because the new peak voltage does exceed the filter cap rating but that's like dropping rocket fuel into a bunsen burner and wondering why you can't control the flame


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