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Vacuum Tube Testers - helpful tips
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Author:  Les [ 29 May 2012, 15:06 ]
Post subject:  Vacuum Tube Testers - helpful tips

Here is a helpful tidbit for use with your Eico 666.

The EICO 666 is the early version of the EICO 667. As such the setup of the testers is, for the most part, exactly the same for both models. These testers have a bank of levers that setup the tube elements, voltage ranging for the grids, screens and plate, and a shunt ranging used for setting the shunt on the meter for proper reading of the current. Where you run in to differences is due to the range of tubes they are capable of testing. The Eico 666 will test tubes that have up to 8 pins where as the Eico 667 has the ability to test tubes up to 12 pins. Because of this, the number of setup levers is different. The levers on the Eico 666 are labeled thus:
1 - 9, C, V, S
While the levers on the Eico 667 are labeled thus;
1 - 12, C, V, S
The numbered levers correspond to pin numbers on the sockets. "C" is the plate cap clip. "V" set the voltages for the elements and "S" sets a shunt resistor on the meter.
Now, where this information becomes useful is for the fact that when Eico introduced the 667, they stopped production of the 666, but of course tubes were still being produced and the tube charts were continuously updated. The charts for the 667 can be used with the 666 if you know where the differences are. And it really is simple. Below is a reference example I used to help another DIYer who was having difficulty with this very issue.

The chart sample is from the Eico 667 chart data. As you can see, the "Levers" group has 13 positions indicated. The Eico 666 only has 10. So the user, when using a Eico 667 chart for the Eico 666 is faced with the apparent dilemma of “how do I make this chart work”. It is actually very, very simple. It helps to understand how your tester works and what each lever represents. It is easy to over think and go wrong or say “I don’t know”. As you can see in the reference, I have broken down how the grouping applies to the Eico 666. Just remember, each numbered level corresponds to a pin in the socket and nothing more. So when you’re working your Eico 666 from an Eico 667 chart, you will simply ignore the lever setting for levers 10, 11, & 12.

For visual comparison:


I know someone is probably looking at the reference given above and comparing it to the setup of a 0A2 from the Eico 666 chart. And he is probably thinking "wait a minute, these aren't the same settings, Les must be wrong". Yeah, I noticed that too. Actually, they're both correct for both models. However, the settings presented for the 0A2 from the Eico 667 chart is more correct. The Eico 666 chart has you set filament voltage to 117v and pin 1 (lever 1) is connected at filament supply. Pin 2 (lever 2) is set at GND. Pin 4 (lever 4) is also taken to GND. The remaining pins are "open". The Eico 667 chart ignores a filament setting (actually says 0), and instead selects a higher plate drive using the "V" lever and Plate setting @ "60" (that doesn't mean 60 volts). The levers therefor connect pin 1 (lever 1) to PLATE, lever 2 to GND and all others "open". What does this represent? Over time, Eico updated their test parameters to give a more accurate result. This was apparently one of those updates.

:beerchug: CHEERS!!

Author:  Gio [ 07 Mar 2014, 18:24 ]
Post subject:  Re: Vacuum Tube Testers - helpful tips

Hi folks.

Great news. I picked up an EICO 667 tube tester locally. It's great when you can meet a nice person with similar interests, pay cash and avoid postage, paypal, ebay, customs. The unit seems like it is in good working order. It needs some cosmetic work, clean up, new power cord, knob ... Minor stuff. The common sockets are well worn and a few of the odd sizes look like they are unused.

Once it is cleaned up it will look nice beside my EICO 625 which I purchased in restored condition and calibrated against a supposedly calibrated tester. ;) It came with a measured tube (emission test) so I will have to compare to the EICO 667. Of course the problem with that is that if they don't match ... well, I won't know which is correct or if both are wrong! :confused: Stay tuned... and photos to come too!


Author:  bluesboyst [ 18 Oct 2017, 21:28 ]
Post subject:  EICO 667 tube tester help

Hi....I have an EICO 667 which was working fine. It works fine testing 6L6 tubes but does not work for 12AX7's. I tried about 8 different 12AX7's and I cannot get the tube to light up....these tubes are good.....any idea why the tube will not light up when in the socket to test them?

Author:  Gio [ 18 Oct 2017, 21:47 ]
Post subject:  Re: EICO 667 tube tester help

Are you adjusting the heater voltage setting? There is a knob which controls the voltage for the tube heaters. The 6L6 is a 6.3V tube and the 12A_7 are 12.6V heaters. Be careful, if you put 12V on a tube with 6V heaters, you will likely damage the tube.

Author:  bluesboyst [ 19 Oct 2017, 07:46 ]
Post subject:  Re: EICO 667 tube tester help

There are 3 knobs I set... Plate, Grid and Filament....all where set to listed values.

Author:  Geek [ 19 Oct 2017, 12:52 ]
Post subject:  Re: Vacuum Tube Testers - helpful tips

Idea - Topic change to "Tube Tester Tips" and pinning it?

Author: [ 22 Oct 2017, 09:25 ]
Post subject:  Re: Vacuum Tube Testers - helpful tips

Good idea Gregg. Thanks for the suggestion. Changed to sticky.

Author:  Gio [ 22 Oct 2017, 09:29 ]
Post subject:  Re: EICO 667 tube tester help

bluesboyst wrote:
There are 3 knobs I set... Plate, Grid and Filament....all where set to listed values.

Sounds like the 9-pin socket may not be getting the heater voltage. You should be able to confirm this with a DMM without having to open up the unit. If you don't have voltage on the heater pins you will have to open it up and start by checking for a broken wire around the socket heater pin tabs.


Author:  hujingdi [ 22 Feb 2019, 01:19 ]
Post subject:  Re: Vacuum Tube Testers - helpful tips

Good, beautiful equipment

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