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OT - Got My Tube Tester Yesterday

Started by Paul Marossy, July 20, 2004, 09:20:04 AM

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Paul Marossy

July 20, 2004, 09:20:04 AM
Won an auction a few days ago for an EICO 625 tube tester that has been reconditioned and is in very good shape considering it was manufactured in March 1959. Anyhow, it tests all the common guitar tubes and an amazing amount of tubes in general. I bought it because I got tired of guessing what condition my tubes are in. I think an investment of $80 is worth it. It's not a Hickock (however you spell that), but a good emission type tube tester for the money.  8)

Looking at the insides is a trip. Stuff I have never seen before in there. It must have been a challenge to design something that can check 100's if not 1000's of tubes...

Lonestarjohnny

#1
July 20, 2004, 12:19:02 PM
Hey Paul,
The 625 is a very good old tube tester, and you got a great deal on it, Eico was my dad's fav brand, I still have his old tube tester, when I get my site up i'll have pic's of a lot of old stuff, My first Scope, a Heathkit, and my first tube tester, an Eico also, can't remember the Model offhand,
there is a lot of info out there for these tester's also, you can find tube setting chart's for a lot of the newer tube's that it will also test,
Just hit some of the tube tester sites,  8)  8)  8)
JD

Paul Marossy

#2
July 20, 2004, 04:17:46 PM
Yep, that's a cool little tester. I downloaded a manual for it off the 'net before I even got it in my hands. It won't test for Mu, but at least it gives you some idea of the condition of the tubes under test.

There's an interesting write up on tube testers here: http://www.tone-lizard.com/Eico.html

ErikMiller

#3
July 21, 2004, 03:46:19 AM
Congratulations on getting the Eico. I have an Eico 667 tube tester that I got from my surplus dealer. Looks like it was a great old company; kind of a poorer man's Heathkit.

In the manual that came with it, they tell how to work up your own settings using the tubes' specifications. Very handy, even though it's not likely that there's been a new tube released since their charts were printed.

I don't always agree with the settings they suggest. All my 6AL6's were testing borderline until I checked the settings against the procedure for creating settings.

Paul Marossy

#4
July 21, 2004, 10:06:09 AM
Thanks.  8)

Isn't that Model 667 the that measures transconductance? That is a step up from a simple emission tester. And, with that you really could match tubes...

ErikMiller

#5
July 21, 2004, 05:06:56 PM
The 667 was the last model of their top of the line, and yes, it measures what they call "dynamic conductance," which is a combination of mutual conductance, plate conductance, and emission.

So I don't get an exact measurement in mhos, but a relative "merit" number. It's good for comparing tubes with each other.

They go for under $100 on eBay. Good deal.

Paul Marossy

#6
July 21, 2004, 05:10:13 PM
That's right they called it "dynamic conductance"....
Hmm. I'll keep an eye for one of those.

Gilles C

#8
July 23, 2004, 10:34:02 AM
When I find the time, I'll have to to a recap job on this one that I got for free. It's kind of working, but the needle keeps shaking.

http://www.finitesite.com/gtechblues/photos/TubeTester.jpg

I forgot about it. But you reminded me that I had to fix it...

Hey, it also checks transistors.

I re-checked the instruction booklet (dated 1967), and it says that PNPs are the most popular...

It tests for gain and leakage. It could be interesting to check a few germaniums when it's fixed.

Paul Marossy

#9
July 23, 2004, 10:48:20 AM
Very nice, Gilles.  8)
It looks pretty user-friendly.

Gilles C

#10
July 23, 2004, 11:20:53 AM
Right Paul,

I just tested it again, and the needle swings like hell.

But when I saw the price you paid for yours, I felt ashamed of not at least trying to fix mine that I got for free...  :oops:

But when I was younger (in the 60-70s), the Eico was the standard for DIY. As were Eico oscilloscopes.

That one (Mercury) was owned by a tech, and given to his son (a friend of mine) when he quit working in the field.

Paul Marossy

#11
July 23, 2004, 11:53:35 AM
I'm certainly no expert on tube testers, but a bad cap or two sounds like a reasonable estimation of the problem with the wavering needle. I can't imagine the meter itself being bad, although I suppose that's not impossible.

ErikMiller

#12
July 23, 2004, 01:54:46 PM
Yeah, Gilles, that's a sweetie there, as it can be used to match.

Having the ability to do that lets me buy up old tubes at the swap meet and then match them. Nice ability, in addition to the main use of the tester in my amp repair business.

Gilles C

#13
July 24, 2004, 12:00:28 AM
:)  As soon as I'm back from vacation (1 week left), I'll check it out for sure.

Then I could start searching for used tubes...

Thanks for the motivation guys.

Oh, and btw, 2 weeks ago, I ordered a Berhinger MIC200 to be able to experiment with a 12AX7 preamp, and see what I can do from there, a DIY and a commercial side by side...

http://www.behringer.com/MIC200/index.cfm?lang=ENG

They say they carefully select the 12AX7, and I like how their products sounds, so...

Fret Wire

#14
July 24, 2004, 12:13:03 AM
I have the Sencore TC-162 and TC-142 Mighty Mite's, both basically like Paul's in function. The 162 is solid state, and the 142 uses a 12au7, which needs calibration more often.
http://www.ndh.net/home/schlangen/roehren/sencore_tc162/sencore_tc162_e.html
I'm eventually going to get an MU 140 or MU150, which does mutual conductance.
Fret Wire
(Keyser Soze)

Fret Wire

#15
July 24, 2004, 12:51:55 AM
Fret Wire
(Keyser Soze)

Paul Marossy

#16
July 24, 2004, 01:03:53 PM
Thanks, but I have already rounded up a manual before I even received the tube tester.  :)

It looks like they had three versions of that Model 625 tube tester:

1. One was like the one I have.
http://www.diyguitarist.com/Images/EICO625-Front1.JPG

2. Just like the one I have, but with a hinged cover over the controls.
http://www.tone-lizard.com/images/Eico_625.jpg

3. Blue front on it like what is shown on that site linked above.
http://www.tone-lizard.com/images/Eico625.gif

Regan

#17
July 25, 2004, 01:56:01 AM
Cool little unit!
You might find you will go on a testing frenzy and test every tube you can find and then start raiding them out of stuff just to test-then you will box it up and use it very little.
I have 3 tube testers, all b&k dynamic mutual conductance models(650,700,707), two of them a recent purchase, but I have had one for a few years now.
The fact of the matter is, you really can't match tubes well on anything but a labratory grade tester like an avo, etc.
Another thing is, just because a tube tests weak, doesn't mean it sounds bad. Lots of mullards don't have the gain that other 12ax7's have, but they still sound great. I find that I keep the weak tubes for myself, and sell the "good" tubes to others.
Most people that I know with tube testers only really use them for testing shorts and grid leaks.
Bottom line is, its another tool in the box, but its not as good a tool as your ear. But they are a cool looking tool:)
Regan
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