New tube tester eico 666

[menger66]

My buddy found this at the high school where he work at it has all the manuals along with some nice sub books it seems to be working though I have a lot to learn about it yet. Any thoughts err or reviews on this tester?

[Leo_Gnardo]

Bound to be a devil of a tester.

More or less a go/no go like my Knight. And even that isn't always accurate. It'll tell you if you have short circuits, and whether a tube has emission. Won't tell you about noise or gain. I've seen some users of these kind of testers claim that 12AX7 & similar tubes sometimes test low on the meter, but seem to work just fine in amps. So don't panic and toss out pre tubes just because they don't hit hi marks on the meter.

These type of testers also use a fairly low voltage on tube plates. Power tubes that test OK with 175-200V, no guarantee they'll behave themselves when you put 400, 500, 700V on them in a real amp.

Restoring it, the usual things. Clean switches & if there's any electrolytic cap, replace it. If there's no fuse it may be a good idea to fuse the AC line.

Some old tube testers had selenium rectifiers. You'll want to replace those with silicon, much more reliable and won't emit a cloud of noxious smoke should they fail.

I put a couple test points on mine to read filament voltage. You can test your tubes at a proper - usually 6.3V - filament voltage. And go one step further, dial filament voltage to whatever your amp is really supplying.

[Phil_S]

I love it on eBay when someone selling tubes shows the lit up tube in one of these with the needle in the green range.

Nice find anyway. Enjoy it.

[ampmike]

I found the same one at a car show flea market.I like the rollex tube chart.Mine probably needs some cleaning and care.I have a smaller one I use often,I think I paid 35 bucks,Good luck,Mikey

[beasleybodyshop]

I recently found an Eico 667 and have restored it. Good little tester. It tests for "Mutual Conductance" which isnt necessarily grid emission but not as accurate as the Hickock circuit testers, like a TV3/7 or a 600, etc.

For what it's worth, i tested a whole slew of known good and bad tubes from a TV7 tester that i fully calibrated and restored (meter movement refurb and calibrated, new caps, adjusted, calibrated, yadda yadda) and With a little work understanding the dial indications I was able to interpret similar testing results to the TV7...very similar, within 5 percent i'd say. So yes, not something i would encourage use for testing and selling to the hifi crowd but its a good go/no go tester that with a little work can provide some info on tube life and heather/cathode shorts test.

[beasleybodyshop]

also, be aware that the roll chart in these things is notorious for being inaccurate. There is a final master chart floating around the web. print that bad boy off and chuck the roll chart. It's especially inaccurate for 12AX7s

This is a bit anal, but i went and replaced every resistor in mine with 1 percent Dale RN series, with the exception of a few. Yes, that was nuts, but it ensures accuracy. I love mine.

If you can't tell

[menger66]

Thanks BBS, I may go through this tester next winter as a project, It's in pretty good condition and works fine for now, but im sure it could use a going through. My buddy that gave it too me works at the high school and finds goods stuff for me every now and then. mark

[johnnyreece]

Here's a handy spreadsheet I found on the interwebs. Note that there are multiple tabs. I just bought a 667 myself and have been looking over info.

[beasleybodyshop]

I would put some diodes back to back across the meter. These is info on this somewhere...Google it.

Also there is a mod to install a bayonet lamp in series with the bias control to prevent damaging it if there is a shorted tube. Once again, there is info with a Google search...sorry but I can't remember off hand.

[danno2000]

Here's a handy spreadsheet I found on the interwebs. Note that there are multiple tabs. I just bought a 667 myself and have been looking over info.

That only works for the 667, too many lever positions in spreadsheet. I did some camparisons using 12ax7, 6x4, 6sn7...do more later , the 12ax7 all read low using the latest settings from using the 1978 charts, the rest were ok, I compared them to a B&K 625. When I restore the Hickok 600A I will do another comparison. So the 666 seems to work quite well other than 12ax7, looking at the one speadsheet on the site here for the 667, increasing the grid up to 32 and plate to 88
works quite well.
Dan

[Stevem]

Like Leo posted that's strictly a emissions tester and a go no go tester in regards to shorts in a tube, it will not tell you how well a given tube amplifies signal/ current.

This type is ok for testing Recto tubes although as Leo posted once again they do so at a far lower voltage then the average amps uses so in regards to Recto tubes and output tubes they could still be bad and arc over on you in a real amp.

Another thing that folks do seem to know is that as a tube that is used to amplify signal gets weaker it can still be / sound ok in a given amp , but there comes a big change over point where the tubes does not respond as fast to in coming signal and will not follow your playing dynamic' s all that well or the speed of your picking!

[martin manning]

It’s more than an emission tester: http://tone-lizard.com/eico-666/