Calibrating Eico 666

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Calibrating Eico 666

Post by bagzy on Tue Mar 20, 2012 3:45 pm

Hi all, I received this tester and suspect it's been stored for years.
I have all the relevant info required concerning the unit I'm working on but must admit
that I'm by no means an expert of any kind when it comes to electronics.
First thing I did was deox all sockets, pots, toggles and push buttons.
Then I swapped out R8 and R19 for new 270K resistors.
The Cal. instructs state to connect an ac voltmeter across the 0-130v taps of the power transformer.
This is where I'm guessing to connect my DMM test leads to the outside legs of R1.
If this is correct, I can only get a max 30vac reading at the pot's highest setting when the instructs state to set R1 to 130vac before adjusting R7.
Can somebody set me in the right direction? TIA.
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Re: Calibrating Eico 666

Post by Bill Cahill on Wed Mar 21, 2012 3:01 am

Caps, electrolytics, redtifier?
Have you replaced any of this?
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Re: Calibrating Eico 666

Post by bagzy on Wed Mar 21, 2012 12:02 pm

Thanks for the reply Bill.

Per your suggestion, I'll change the caps and electrolytics.
BTW, I'm still wondering if my test leads are in the right place for the transformer taps? I have them hooked up to the outside legs of the Line Adjust pot(R1) which trace back to the transformer?
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Re: Calibrating Eico 666

Post by Bill Cahill on Wed Mar 21, 2012 2:02 pm

That doesn't sound right. That's on the primay of the transformer. You want to check the secondary voltage while rotating control. But, why are you concerned with that? Seems you have more important issues, first.
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Are you sure the meter movement in equipment is good?
Careful there. Some movements are very low resistance, and, if you try to put an ohm meter on them you'll peg the movement, and, may dammage it.

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Re: Calibrating Eico 666

Post by bagzy on Thu Mar 22, 2012 12:43 am

I see your point Bill, it's probably not constructive trying to calibrate the tester with old components.
I have the original parts list and will have to figure out how to cross reference to today's part numbers.
See, I told ya I was a total noob but I hope I'm learning something as I go.
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Re: Calibrating Eico 666

Post by Bill Cahill on Thu Mar 22, 2012 3:14 am

No, I didn't mean that. First, have you replaceed any paper caps? Electrolytics?
Have you cleanned switches?
What is the tester doing?
What is your complaint? Is it working at all?
There are two selenium rectifiers in this thing. One is for voltages. Maybe it's gone South??
What is, or, isn't the tester doing???
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Re: Calibrating Eico 666

Post by bagzy on Thu Mar 22, 2012 12:44 pm

I did clean every movable part with contact cleaner including all pots, switches,toggles and sockets.
I have a box full of NOS tubes and tested a few and the tester does work.
Before I rebuild this thing, I thought I could recalibrate it to see if I'm getting accurate readings or not.
The owners manual is too vague for me to figure out where I should connect my DMM to the transformer taps to set the calibration.
I appreciate your patience Bill. Very Happy
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Re: Calibrating Eico 666

Post by Resistance is Futile on Thu Mar 22, 2012 8:25 pm

The adjustments should be made with a tube in place for a load on the transformer. If you have no load on the transformer the the voltages may be a tiny bit high, but not enough to be of concern. I personally would use a tube and a multimeter. JMHO.
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Re: Calibrating Eico 666

Post by bagzy on Thu Mar 22, 2012 9:30 pm

Hi Resistance is Futile, you must be a Star Trek fan like me. Gotta watch an episode or two everyday. lol!

I would be really grateful if you could look at the owners manual on page 8
http://bama.edebris.com/manuals/eico/666/
and possibly explain to me where I connect my voltmeter to the transformer taps so I can calibrate it. I would need to follow the second last page marked 10C of the assembly PDF found here.
http://bama.edebris.com/manuals/eico/666/assembly
Thanks for any assistance you can provide.
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Re: Calibrating Eico 666

Post by Resistance is Futile on Sat Mar 24, 2012 6:10 am

You really don't need to know what the taps are. When you use the selector switches, it connects to the correct filament taps. All the tube sockets in the tester get the same taps selected at the same time.

So if you select a 6V6 or 6L6 to test and follow the chart setup then you have selected the 6 volt tap on the transformer. If you look up a tube in any tube manual it will show which pins on the tube are the filament ones. The other tube sockets in the tester will also have the same voltage at the same numbered pin sockets.

So set your Multimeter at the correct AC voltage range, and turn on your tube tester after setting the switches according to the tube setup chart then insert your tube in the correct numbered socket in the tube tester. Then on any adjacent tube socket insert you multimeter test probes into the same numbered pin sockets.

So if the tube chart calls for the filament pins as #1 and #8 then that is the same voltage (6 volts ac.) on all sockets on the tube tester, so insert the probes into any socket numbered 1 and 8. The tube lights up and now the transformer in the tube tester is loaded and should give the correct (voltage it may vary slightly), but that's where the the adjustment switch or variable pot for voltage line adjustment comes into play (you can however use it to set the filament voltage as a finer adjustment, just remember that the by using the line adjustment it not only adjusts the primary AC voltage but the filament voltages at the same time). By the way most tube testers use the built-in meter to indicate line voltage. Most tube testers are set to operate on 110 or 115 volts ac.

So if you measure your house voltage you will find it a little higher. That's why in the tube testers there is an adjustment for line voltage. If you want to test a 117 volt tube just follow the same procedure and read your meter and adjust the line voltage and you should be set.
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Re: Calibrating Eico 666

Post by bagzy on Sat Mar 24, 2012 1:06 pm

Thank you very much for that explanation.
Now I have a better starting point and a noobie like myself really appreciates clear instruction like you've given.sunny

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Re: Calibrating Eico 666

Post by Resistance is Futile on Sat Mar 24, 2012 5:13 pm

Yes I know where your coming from. Psst! I wish I had me for a elmer when I was learning all this new fangled electronics. pale Cool
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Re: Calibrating Eico 666

Post by Mike C. on Tue Jan 22, 2013 7:05 pm

The only problem with calibrating the Eico 666/667 by measuring the filament voltage with a tube installed,is the test data was compiled with a tester that was probably calibrated using the method outlined in the owner's manual.

The merit test results are affected by using a different calibration method.I calibrated mine per factory instructions,and when I install a tube and measure the filament voltage,it
is extremely close ,or dead on.

That being said,frankly I don't think it matters whether the 666/667 is calibrated or not.The test data is so loaded with errors you can't really trust the merit readings all that much anyway.Not trying to rain on anyone's parade,just stating my own observations.

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Re: Calibrating Eico 666

Post by bagzy on Tue Jan 22, 2013 9:15 pm

I was given an equivalent replacement diode rect. and a cap went up in smoke because of it. So much for straying from the schematic.
I have to wait a while for other things to show up and will be putting in an order for parts.
Not in a big hurry to get the 666 working but it is on the to do list.
Is factory calibration any different from the owners manual?
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Re: Calibrating Eico 666

Post by Mike C. on Wed Jan 23, 2013 6:43 pm

bagzy wrote:I was given an equivalent replacement diode rect. and a cap went up in smoke because of it. So much for straying from the schematic.
I have to wait a while for other things to show up and will be putting in an order for parts.
Not in a big hurry to get the 666 working but it is on the to do list.
Is factory calibration any different from the owners manual?

I have a feeling that you put the diode in backwards.The marking on the original is very confusing if I remember correctly.

The calibration procedure outlined in the owner's manual is the same as the factory calibration,I should have stayed with one term.

I didn't mean to make it sound in my previous post that the Eico 666/667 aren't good testers,they are, in my opinion.The data errors just make the learning curve with these units a tad long.I've had a 667 (actually,2) for almost thirty years.After a while, you'll have the bogus data sifted out and everything will be fine.

Fred Scoles,a member over at ARF,was kind enough to make me a copy of the very newest data book for the 667.I didn't even know that book existed.It appears to have fewer errors than any of the other books.

If you contacted him,I'm sure he would make you a copy if he has time.He charges a very nominal fee to cover ink and the exceptionally large paper he uses.

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Re: Calibrating Eico 666

Post by Resistance is Futile on Thu Jan 24, 2013 4:42 am

bagzy wrote:Hi Resistance is Futile, you must be a Star Trek fan like me. Gotta watch an episode or two everyday. lol!

I would be really grateful if you could look at the owners manual on page 8
http://bama.edebris.com/manuals/eico/666/
and possibly explain to me where I connect my voltmeter to the transformer taps so I can calibrate it. I would need to follow the second last page marked 10C of the assembly PDF found here.
http://bama.edebris.com/manuals/eico/666/assembly
Thanks for any assistance you can provide.
----------------------------------------------------------------
first off, you have one side of the transformer primary connected to pin 2 of the line adjust pot. (this is the center tap-don't measure that off that one)That will have the full line voltage of 110-120 Vac.

1. you can measure your voltage off of the fuse holder (either end) with one probe.
2. then try both of the outer pins on the line adjust POT 200 ohm (R1) pin 1 or pin 3. The one that has the higher voltage is the one to use.
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Re: Calibrating Eico 666

Post by easyrider8 on Mon Mar 25, 2013 1:29 am

When calibrating the 666 you connect your voltmeter to the primary side of the power transformer, one lead can connect to the fuse and the other to one end of the rheostat, if you connect to the wrong end of the rheostat you will never get the voltage to 130.

I was a bad move to use deoxit on the sockets and switch's as this will cause problems on the leakage tests. You may have to wash the deoxit out with another cleaner. The only way to use deoxit on a tube tester is sparingly on the tip of a "Q" tip.

The only other problem you may have is "whiskers" growing in the adjustment pots, you may have to take them apart and clean them.

Everything else to self explanatory, just follow the manual.

Dave
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