Check shorting pins of tubes

[grtamp]

Hi all, There is a simple circuit to use for testing short pins of the tubes?

I have a multi tap transformer and maybe I could build a shorting tester.

my PT secondary:
0 - 130V @ 45mA
0 - 60V @ 30mA
14 - 0 - 14V
0 - 9V 45mA

Thanks
R.

[pompeiisneaks]

If a pin is shorted, it will test positive with a multimeter on continuity mode.

You just test making sure none of the pins beep except the heater pins that must have continuity.

One of the easiest tests on a tube. I did a video on it a long time ago and it's still one of my top viewed videos.

It's a quick go/nogo test for a tube if you're seeing continuity between anode and heaters say (what I had happen to mien and burned up the entire amp tubes heaters sending 400V down the string)

~Phil

[grtamp]

Hi Phil, Thanks, but I thought the tube under test must be in power on condition!!?!! Like old tube tester!

[pompeiisneaks]

That was just an 'added function' of the tube testers from my understanding. I may be mistaken, though. Are there cases where the tube doesn't short at low voltage/current but at full voltage/current it does? Maybe some kind of arc damage that happened?


From wikipedia on tube testers:

Short circuit test
Usually, emission testers also have a short circuit test which is just a variation of the continuity tester with a neon lamp, and which allows to identify if there is any shortcut between the different pairs of electrodes.


~Phil

[grtamp]

Hi Phil, make some test with DMM in continuity mode on some shorting tubes, but the test don't work!.. When the tube is pulled into the amp , the fuse blowing, so your suggestion is not ok for me.

Someone have an idea for a little circuit for check tubes!
Thanks
R.

[pompeiisneaks]

The blowing of the fuse in and of itself doesn't mean the tube is 'shorting' it could mean there's something seriously wrong with the tube otherwise, like it's gone gassy etc, it could be a component issue where the tube is conducting too much too fast.

A short, by definition means that you get continuity between two points. In tubes the only continuity you should get ever is between the heater pins.

If the tube is 'arcing' that's a different failure state and is somewhat hard to test for, unless you get it up to full voltage of the tube operating range, and then detect current flow and see if it suddenly spikes at a certain point (you'll also HEAR it when a tube arc's with a popping noise).

Maybe I'm misunderstanding what you're asking?

~Phil