LordWellfleet
Joined: Jul 12, 2012
Posts: 171
Cape Cod, USA
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Posted on Jun 14 2016 12:42 PM
I couldn't find this subject already in the forums, so I'm hoping to tap into some group wisdom. (And I must confess, I'm woefully under-educated on tubes and electronics in general.)
Can anyone point me to a decent tube tester? Do such things still exist? In days gone by you'd see them in places like drug stores or anywhere else you could buy tubes. I'd prefer a new one, as I fear buying a vintage one might require a tube tester tester.
Here's why I ask: Last night I thought my tank had a bad tube. So, I replaced it. After replacing it, the unit still sounded dry and thin--that is until, employing the ancient wisdom, I thumped it on the side with my fist. That got it working great--I might say better than ever! But, was it the tube change and the thump? Or was it just the thump that "fixed" the tank? Is the original, replaced tube is OK? I have no way of knowing.
—
Everybody up!
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bamboozer
Joined: Jan 18, 2010
Posts: 672
Delaware
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Posted on Jun 14 2016 03:54 PM
There out there somewhere, on the hunt for one myself, but for me used is fine. As you stated there used to be thousands of them at drugstores, usually stocked full of tubes as well.
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Surf_Skater
Joined: Sep 06, 2012
Posts: 1300
Lawrenceville , GA
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Posted on Jun 14 2016 06:26 PM
Apparently Orange makes one. Kind of pricey unless you have to test a lot of tubes. Here's a link for one on Craigslist.
http://atlanta.craigslist.org/nat/msg/5631594581.html
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eddiekatcher
Joined: Mar 14, 2006
Posts: 2778
Atlanta, GA
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Posted on Jun 14 2016 07:14 PM
When the thump on the unit improved the sound, that was an indication that you probably have a poor connection somewhere or a cold solder joint. Of course it could be a tube with a flakey internal connection. If swapping the (a) tube (s), didn't reveal the problem proceed with caution......
With the unit active in the circuit and plugged into a live amp, try tapping on each of the tubes with your finger nails. I use a fluttering probe with the nails on several fingers. A microphonic tube should make noise with this probing. Then I wiggle the tubes around in their sockets to see if this makes noise while the unit is active. A lot of bad connections can be traced this way. If this makes it act up, reseat the tubes in their sockets several times. Then go on to the RCA cable connections on the chassis and on the pan. You can tighten the outside of these connections to improve their signal ingegrity.
Then.....and remember, THE UNIT HAS HIGH VOLTAGE PRESENT AND CAN KILL YOU, if you want or need to get into it more, Remove the back cover and probe each of the component solder joints with AN INSULATED instrument. I use a small strip of thin plywood but a lot of techs use a chopstick or something comparable. Normally if a problem is lurking, you will hear it through your amp. Cold solder joints are really quite prevelent. If the tube wiggling indicated an issue but didn't correct the problem have your tech re-tension the tube sockets. But remember, the tube sockets have high voltage present and the filter caps in the reverb unit can store this or part of the high voltage for several days. Be careful use only an insulated probe. No screwdrivers, lead writing pencils, etc. Always leave one hand behind your back while performing these tests as to not allow a potential electrocution by accidentally leaving the other hand in contact with the chassis or some other ground potential.
My dad was a ham operator and had several very high tech, for the time, tube testers. I never used them much. Swapping out tubes is way cheaper and really does a quicker job.
Good hunting,
ed
— Traditional........speak softly and play through a big blonde amp. Did I mention that I still like big blonde amps?
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Badger
Joined: Nov 16, 2013
Posts: 4537
Wisconsin
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Posted on Jun 15 2016 06:53 AM
I went to the store with Dad many times as a kid, tube testing stuff pulled out of the back of the TV and those aren't going to give you the full story anyway. Much faster to swap, but first...
Agree with Ed; if you jostled it & it starts working this is almost always a physical-layer issue, i.e., loose pin/tube socket, RCA connections (pipe cleaner with a little Deoxit for the inside of the RCA female joint too is your friend).
Yes, good hunting. 
— Wes
SoCal ex-pat with a snow shovel
DISCLAIMER: The above is opinion/suggestion only & should not be used for mission planning/navigation, tweaking of instruments, beverage selection, or wardrobe choices.
Last edited: Jun 15, 2016 06:54:14
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LordWellfleet
Joined: Jul 12, 2012
Posts: 171
Cape Cod, USA
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Posted on Jun 21 2016 12:55 PM
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skeeter
Joined: Feb 27, 2006
Posts: 2065
Virginia, USA
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Posted on Jun 21 2016 01:51 PM
What? You mean I can't find one of these down at the local Rexall anymore?
— Paul
Atomic Mosquitos
Bug music for bug people is here!
Killers from Space
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eddiekatcher
Joined: Mar 14, 2006
Posts: 2778
Atlanta, GA
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Posted on Jun 21 2016 04:23 PM
Hey Skeet,
Did you find that one on American Pickers?
It's a doozie. You ought to consider working it in to an Atomic Mosquitos' show............
ed
— Traditional........speak softly and play through a big blonde amp. Did I mention that I still like big blonde amps?
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eddiekatcher
Joined: Mar 14, 2006
Posts: 2778
Atlanta, GA
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Posted on Jun 21 2016 04:49 PM
Every now and then I get the urge to bring out some of the really cool stuff and here is an example. Like Leo Fender, my dad at one point, had a radio repair shop. In 1936 he bought this "Supreme Model 89 Deluxe" electronics tester. It is designed to test resistors and capacitors as well as tubes. Inside the compartment on top is the original certificate of calibration dated January 20, 1936. I have his original VTVM (vacuum tube volt meter), RF signal generator and an NOS Central Electronics Oscilloscope from 1952 which is still new in the box.
Unfortunately, a lot of his test and ham radio equipment from the 40's and 50's was stolen from my mom's house by service people who worked on the furnaces and hot water heaters after my dad passed. The greatest loss to me was the National Radio HRO receiver and all it's plug-in tuning inserts.
I just get sick thinking about that callus bastard who over time, cleaned out my dad's ham shack.
ed
— Traditional........speak softly and play through a big blonde amp. Did I mention that I still like big blonde amps?
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JohnnyMosrite
Joined: Jun 14, 2006
Posts: 910
New York City area
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Posted on Jun 21 2016 05:50 PM
To the eddiekatchers and such in the world;
1. Never take your eyes off valuable equipment - especially with contractors who probably use illegals to save on costs. I either make the effort to remove my stash if foreign (as in I don't know them) contract workers are about or I keep my eyes open. It's not that I don't trust them; I don't trust anyone.
2. Yes - tubes have high voltage - but it isn't the voltage that kills you; it's the amps. (3 amps in a guitar amp is more than enough to smoke you). Don't believe me? Try this simple experiment in the privacy of your own home:
Get 8 flashlight batteries and wire them up in series - you want 12 volts.
Now get a couple of alligator clip leads, hook up to + and - on battery pack and put the other two leads in your mouth or attach to some sensitive body part (ahem). Note the sensation.
Now repeat with a 12 volt car battery that's rated at 50-75 amps. Assuming you survive, note the difference in sensation. It was the same voltage but the amps (should have) made a difference. Your body will draw the the larger amperage. The flashlight batteries are way less than 1/4-1/2 amp
Kind of like the difference between getting hit with water by a squirt gun and hit by a fire hose.
Some pearls of wisdom provided by yours truly..
J Mo'
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JohnnyMosrite
Joined: Jun 14, 2006
Posts: 910
New York City area
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Posted on Jun 21 2016 05:55 PM
Regarding original thread. HITCOCK military grade tube testers from WWII are great. they use to be cheap..they pop up on ebay every so often. If you have a tube amp, a tube tester is a must. Replacing a tube is expensive these days.. I'm cheap and save my pennies. I don't toss a tube unless it is out of spec or truly dead.
BTW - maybe you shouldn't try that experiment I just related at home, boys and girls.
J Mo'
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