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 Post subject: Eico 667 Improvement
PostPosted: Feb Thu 03, 2005 4:49 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 7
Location: Toronto, ON Canada
Hello Guys, I just picked up a few EICO tube testers from eBay, I know that makes me an idiot. I have 2 625's and a 667, the 667 has a bizarre meter problem. Befor even plugging the unit in, if I touch the meter or touch in in any way it goes nuts flipping all over the place. Any ideas?<P>Regards<P>Anthony<P>------------------<BR>


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 Post subject: Eico 667 Improvement
PostPosted: Feb Thu 03, 2005 6:50 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1982
Location: Oswego, NY, USA
The problem might be static charge. To see if it is, the next time the pointer goes nuts huff your breath on the meter lens (face)to see if it settles down. If that helps, then wipe a little diluted dishwashing detergent (in clean water so it leaves no streaks) on the meter face and leave it there, so it will control the static. And the next time you may have to disassemble the meter for other maintenance, also wipe some on the inside surface of the lens. Various anti-static products, such as Staticide also work. Meter faces always receive a light coating of anti-stat at the factory, but can go bonkers in dry weather if someone unknowingly wiped the coating off. Also, some coatings don't last forever.<P>Fred <P>------------------<BR>


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 Post subject: Eico 667 Improvement
PostPosted: Feb Thu 03, 2005 6:58 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 420
Location: Winnipeg, Manitoba, CANADA
Since vinyl records are making a comeback, this may make it easier for you. Years ago I bought one of those vinyl record anti-static guns. It really works. I would try any Hi-Fi shop today; you just never know. I use my gun on tube testers, VTVM's, or even your TO-6. If you have a dry shop, this should help a lot. <P>------------------<BR>


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 Post subject: Eico 667 Improvement
PostPosted: Feb Thu 03, 2005 8:00 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 7
Location: Toronto, ON Canada
Thanks for the tip Fred.<P>BTW Randy I used to use my Static Zapper on my sister. :-)<P>------------------<BR>


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 Post subject: Eico 667 Improvement
PostPosted: Feb Fri 18, 2005 2:42 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 7
Location: Toronto, ON Canada
I checked all the connections on my 667, fixed the meter which was binding, replaced the Diodes which were defective BTW, CR1 was actually wired in backwards!<P>I metered all the resistors and recalibrated the unit with the test proceedure. It seems to measure good and bad tubes as it should, though the meter still has a slight high frequency vibration when you pull the merit switch. It is not there when you do the line AC adjustment.<P>I have tried putting the diodes in but that either causes the meter to immediately move backwards or whack the far right stop when I pull the merit switch. I have tried all 4 variations that the diodes can be mounted between the posts.<P>Any suggestions on the diodes and the HF vibration?<P>Regards<P>Anthony<BR><P>------------------<BR>


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 Post subject: Eico 667 Improvement
PostPosted: Feb Fri 18, 2005 3:36 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 30748
Location: Livermore, CA
Hi Anthony<P> Might try adding a high value, low voltage electrolytic cap (100 mfd @ 25 volts) right across the meter. This should dampen the vibration.<P> I also add two diodes, parallel, back to back, across the meter movement. This prevents hard pinning if the setup is wrong(You won't bend the needle.) <P>------------------<BR>Norm


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 Post subject: Eico 667 Improvement
PostPosted: Feb Fri 18, 2005 6:07 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 410
Location: Tokyo, Japan (2006~)
Hi Anthony;<P>Sounds like you have the oscillation problem Chris H used to tell us how to fix... If your 667 was built from a kit (it does sound that way from a backwards diode), the lead dressing that the original builder did may be causing this on some of the high gain tubes you are testing.<P>Check to see how the leads going to your tube sockets are routed, and are nicely run closed to the bottom surface of the panel plate. Also, Chris H used to recommend to put ferrite beads on the leads close to the tube sockets. I have not tried this since my 666 doesn’t have any oscillation problems, but that was always Chris' standard recipe for this problem.<P>Search for Chris H in the search bar and you should be able find some of his posts that talked about this. It was sometime around last fall, IIRC…<BR><P>------------------<BR>Chris M.<BR>Windy City USA


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 Post subject: Eico 667 Improvement
PostPosted: Feb Fri 18, 2005 9:17 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 7
Location: Toronto, ON Canada
Thanks Chris and Norm, the unit was definately built buy a rank amatuer. The wiring is horendous, also he forgot to tie the wiper to the other side of the pot on the 3K plate potentiometer. I will replace the caps next, I guess I can use any value in place of 10 UF as the are just filter caps to ground? I will try the 100 uF cap across the meter, I will also try testing a few rectifiers to see if I get the oscillation there.<P>With the diodes, so they are both wired between the terminals? In the same polarity as the meter or one foward and one reversed?<P>Regards<P>Thanks again for the pointers.<P>Anthony<BR><P>------------------<BR>


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 Post subject: Eico 667 Improvement
PostPosted: Feb Fri 18, 2005 10:33 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 410
Location: Tokyo, Japan (2006~)
If the tester has been wired as badly as you describe, I recommend picking one of the tube sockets (like your octal since it gets used often for the high current tubes) and re-dress the leads going to it, and see if the oscillations would subside in any magnitude. This should reveal where the problem is originating from....<P><P>------------------<BR>Chris M.<BR>Windy City USA


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 Post subject: Eico 667 Improvement
PostPosted: Feb Fri 18, 2005 11:44 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 10748
Location: Mpls, Minnesota
It is the high mu tubes that have a tendancy to oscillate, not high current, so singleing out the octal socket wouldn't be a complete cure. If the leads are dressed properly you won't have a problem.<P>If you have this problem testing rectifiers it is not tube oscillation, but meter oscillation and the cure Norm suggested will cure it.<P>Dave<P>------------------<BR>Intelligence is the ability to use your knowledge


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 Post subject: Eico 667 Improvement
PostPosted: Feb Sun 20, 2005 10:10 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 7
Location: Toronto, ON Canada
Hello again, I replace the caps with some 47 uF caps and installed a cap on the meter as suggested. This has stopped the needle from vibrating spastically when testin the merit of the tubes. The meter has a nice gracefull swinging motion to it now, kind of cool. When I test a 6SN7 the meter still causes the meter to swing off to the far right, albeit a lot more gracefully and without the vibration and buzzing. A 12AX7 on the other hand reads just fine. I have calibrated the unit an I think I have fixed it's many problems. I just can not figure out why the meter goes off the scale for some tubes. I have tested all the resistors and they are within spec, adjusted all the contacts so the gap is less than the blade thickness to ensure switches are making contact. Other type tubes seem to test fine in the same socket. Any more suggestions Lads?<P>Regards<P>Anthony<P><BR>------------------<BR>


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 Post subject: Eico 667 Improvement
PostPosted: Feb Sun 20, 2005 9:14 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 410
Location: Tokyo, Japan (2006~)
Hi Anthony;<P>My 666 does the same for some tubes also. Its a matter of how "Plate" knob and "S" lever settings in EICO's tube setup data was determined at the time your particular roll chart version was developed. That knob is placed in series with the meter for sensitivity adjustment.<P>You'll find that the "Plate" knob and "S" lever settings vary for the same tube on different versions of roll charts. When you run into this situation, you may want to look up some later Coletronics versions of the setup data and try again. EICO's original data contain many errors. <P>------------------<BR>Chris M.<BR>Windy City USA


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 Post subject: Eico 667 Improvement
PostPosted: Feb Mon 21, 2005 3:19 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 7
Location: Toronto, ON Canada
Thanks Chris, I will look into that. It seems logical as I have some Generic 6SN7 tubes that test "on the meter" and some GTB versions that send the meter on a rocket ride to the right. The 100 uF capacitor suggestion really helps though as the meter now just sort of saunters off the the right. :-)<P>I was reading througn the manual to see what components are in the Merit circuit. I suppose I could look up the specs on the tubes and put a potentiometer and Amp meter in series with the "Merit Circuit" a byoass switch to switch it in and out of circuit and use it to "Compensate" for the settings by limiting the current in the circuit.<P>Regards<P>Anthony<P><P>------------------<BR>


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 Post subject: Eico 667 Improvement
PostPosted: Feb Mon 21, 2005 3:20 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 7
Location: Toronto, ON Canada
Thanks Chris, I will look into that. It seems logical as I have some Generic 6SN7 tubes that test "on the meter" and some GTB versions that send the meter on a rocket ride to the right. The 100 uF capacitor suggestion really helps though as the meter now just sort of saunters off the the right. :-)<P>I was reading througn the manual to see what components are in the Merit circuit. I suppose I could look up the specs on the tubes and put a potentiometer and Amp meter in series with the "Merit Circuit" a byoass switch to switch it in and out of circuit and use it to "Compensate" for the settings by limiting the current in the circuit.<P>Regards<P>Anthony<P><P>------------------<BR>


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 Post subject: Eico 667 Improvement
PostPosted: Feb Mon 21, 2005 5:07 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 410
Location: Tokyo, Japan (2006~)
Hi Anthony;<P>I don't think you should add any extra circuit to compensate for 6SN7G and 6SN7GTA/B. That's what the PLATE knob and the levers V & S do exactly.<P>Try this setting with the 1st triode section of your 6SN7GTB<BR>79-80-5411111-12111-3-3, leakage, merit button use the same as the data you have.<P>Also try (1st triode section):<BR>20-95-5411111-12111-3-2, leakage, merit button use the same as the data you have.<P>These are both 6SN7 settings for my 666 over various versions of published data. I added "11" to the second set of levers since yours is a 667 with two more levers for transistors. Lever Pos. "1" is Ground on 666 and 667. <P>As you can see, the PLATE knob and V & S lever setting is exactly what you are describing as the "circuit to compensate" for the same # tubes with different suffix, which have different ratings and performances. <P>------------------<BR>Chris M.<BR>Windy City USA


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 Post subject: Eico 667 Improvement
PostPosted: Mar Fri 25, 2005 9:55 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 30748
Location: Livermore, CA
Hi Alex<P> Eico 667 is the same as 666 with a few extra levers. These levers connect up to extra pins on the sockets. <P> If no one come up with Eico 667 the 666 schematic is in Alan's book Tube Testers and Classic Electronic Test Gear.<P>------------------<BR>Norm


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 Post subject: Eico 667 Improvement
PostPosted: Mar Fri 25, 2005 10:30 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 10748
Location: Mpls, Minnesota
Schematic sent<P>Dave<P>------------------<BR>Intelligence is the ability to use your knowledge


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