Received "New" Eico 667 Tube Tester - Rebuilding

inspiredsports

Well, the tiptoe in the water part of my tube gear experience is over. I'm all in!

After buying 2 tube buffers, a Dynaco PAS-3X preamp, and then a Conrad Johnson PV-7 preamp, I realized I want to be able to keep tabs on the tubes I own and buy.

On Thursday, I received my first tube tester (a relatively nicely kept Eico 667 built in the mid '60's) that I am completely going through and will be rebuilding.

It is almost mechanically perfect, but I am going to re-tape the Roll Chart, re-glue the roller tubes to the sprockets, and replace the power cord which is getting a bit brittle.

Electrically/electronically, the unit does have a couple of warts that I will be correcting shortly.

I've tested all of the resistors and the two highest value resistors in the Shunt circuit (6 position Lever "S") are bad. The 683 ohm 1/2 W 1% resistor measures 169, and the 171 ohm 1/2 W 1% measures 139. There is a burnt odor coming (I think) from the bad 683.

I appears as if the 10mf 25V cap has been replaced at some point, but I think I will replace it again, and the 10mf 150V is original and will be replaced.

I do have one observation about the 200 ohm Line Adjustment rheostat that balances the 105V-130V taps coming off of the transformer. It does perfectly zero the line, but when measuring impedance I can't get a reading of more than 55 ohms. I'm only guessing, but think maybe because it is an open coil design, it is just oxidized at the higher 130V end of the scale that is never needed to zero the line.

The bad resistors are at settings 4 and 5 on the "S Lever" which only come into play for higher current tubes, so I was able to test an assortment of older "second string" 12AX7, 12AT7, 6922 and 12X4 tubes that I was not worried about losing. I looked up every Eico, Simpson and Coletronics chart I could find on the internet to find a concensus, and the 1978 Coletronics seems to me like it might be the best overall chart to use.

Those tubes all tested out basically to where I would have guessed they should be based upon where they were said to have been when I bought them, and how long they have been in use.

As this is my first foray into tube testers, any general hints about testers and specific hints about the similar Eico 666/667's would be most appreciated.

Well, that's a lot of info for now, so . . .

Happy News Year!
Greg

mhardy6647

Sounds lik you're reasonably well-set, but in case you didn't know/don't have 'em, the docs are available from BAMA.

http://bama.edebris.com/manuals/eico/

I don't have hands-on experience with the 666 or 667, sorry.

Poee7R

Congrats.

It looks to be in good shape. Ive yet to get into tester's, and probably won't for a while. So when you get it up and running let me know if you would like to make a couple bucks testing some tubes haha.


Dave

inspiredsports

Poee7R wrote: »

Congrats.

It looks to be in good shape. Ive yet to get into tester's, and probably won't for a while. So when you get it up and running let me know if you would like to make a couple bucks testing some tubes haha.


Dave

I am really happy so far!

I devoted today to carefully disassembling the various pots and gently cleaning them with a lint free cloth and anhydrous alcohol. I have new caps and resistors on order so I can solder them in and calibrate next weekend.

I really enjoy doing this, but I don't know if the Eico 667 (best Eico made) is worthy of charging a fee for service. If I ever am able to swing one of the top line Hickok's I would feel more comfortable charging a nominal fee.

inspiredsports

I was going to mail order replacement from Parts Express, but I'm not sure the components they list are the best match.

I need:

1 Each - 10 mf 25V electrolytic capacitor
1 Each - 10 mf 150V electrolytic capacitor

1 Each - 3.57 ohm 1/2W 1% resistor
1 Each - 10.7 ohm 1/2W 1% resistor
1 Each - 42.7 ohm 1/2W 1% resistor
1 Each - 171 ohm 1/2W 1% resistor
1 Each - 683 ohm 1/2W 1% resistor

2 Each - 270K 1/2W 5% resistors

Does anyone have any other good online sources they would recommend to order these parts?

ben62670

For matching your machine should be just fine. To get absolute true measurements a more expensive unit may be needed. In my travels matching means way more than actual values.

inspiredsports

ben62670 wrote: »

For matching your machine should be just fine. To get absolute true measurements a more expensive unit may be needed. In my travels matching means way more than actual values.

Yep, The Eico 667 is the best Eico made and very good at about 1/4th the price, but the Hickok 539C is probably the best overall tester ever made (600 and 800 series are great also).

A mint 539C that was listed on eBay just closed Sunday at $825 delivered!

mhardy6647

inspiredsports wrote: »

I was going to mail order replacement from Parts Express, but I'm not sure the components they list are the best match.

I need:

1 Each - 10 mf 25V electrolytic capacitor
1 Each - 10 mf 150V electrolytic capacitor

1 Each - 3.57 ohm 1/2W 1% resistor
1 Each - 10.7 ohm 1/2W 1% resistor
1 Each - 42.7 ohm 1/2W 1% resistor
1 Each - 171 ohm 1/2W 1% resistor
1 Each - 683 ohm 1/2W 1% resistor

2 Each - 270K 1/2W 5% resistors

Does anyone have any other good online sources they would recommend to order these parts?

Mouser or Digikey or Antique Electronic Supply.

ben62670

PE resistors sound dirty. Can you use 1/4 watt R's?

inspiredsports

ben62670 wrote: »

PE resistors sound dirty. Can you use 1/4 watt R's?

Of course a tube tester's resistors don't need to "sound" like Mills. In this case it's just all about adjusting voltages to the various pins of the tube.

The 1% (what Eico calls "precision") resistors are in a circuit with a switch where current is shunted through either the 10.7, 42.7, 171 or 683 ohm 1/2W 1% resistor. This shunted (adjusted) voltage is then sent on its way to the an adjustment pot that fine tunes the voltage that powers the tube being tested's Plate.

The 270K 1/2W 5% resistors are the Main Line Adjust and Leak Test Calibration resistors and the 3.57 ohm 1/2W 1% is in the main "Merit" test line.

I don't want to drop below the 1/2 Watt rating Eico originally specified back in 1966 when this tester was built.

ben62670

Yes sir. I am a freak!