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 Wanted 6E5 Magic Eye
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 Return to top of page · Post #: 1 · Written at 11:49:37 PM on 13 May 2014.
Art's Gravatar
 Art
 Location: Somewhere, USA
 Member since 22 October 2013
 Member #: 1437
 Postcount: 896

Hi Guys,
I'm after a good condition 6E5 magic eye valve if anyone has one to spare.
Mine is working in a radio, but the part that is normally lit at zero volts
is mostly burnt out and dim, only the opening part is bright.
Cheers, Art.


 
 Return to top of page · Post #: 2 · Written at 9:15:01 AM on 14 May 2014.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5239

Did you replace the 1M resistor, normally in the base? Those have an attrition rate rather than a fail rate and are rarely in spec.


 
 Return to top of page · Post #: 3 · Written at 1:25:27 PM on 14 May 2014.
Art's Gravatar
 Art
 Location: Somewhere, USA
 Member since 22 October 2013
 Member #: 1437
 Postcount: 896

Hi Marcc,
Yes the resistor on mine is in spec (1024), though I didn't check it before.
The pattern I mentioned can be seen in the magic eye even when it isn't powered.

Just a question as well... to control the brightness of the entire display,
would you use a resistor for B+, or just use a higher value resistor for the 1 Meg resistor?
Cheers, Art.


 
 Return to top of page · Post #: 4 · Written at 12:52:53 AM on 15 May 2014.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5239

6E5 (VT-138) is very voltage sensitive. Looking at the one in my capacitor tester and another straight on all you should see is the white background and the circular plate in the middle set dead. Alive at full deflection -7.5V possibly a line which if not quite right overlaps.

Target voltage is 250V .2mA (pin4) Triode plate resistor 1M triode plate current 2mA Anode is pin 2

Anode is the one to make sure the voltage is correct albeit you can change the shadow angle by varying the 1M resistor.

There is a tutorial on the web specifically on "eye tubes" That's what the yanks call them. Below shows what you should see with it working.

http://radioremembered.org/tuneye.htm.


 
 Return to top of page · Post #: 5 · Written at 1:38:23 AM on 15 May 2014.
Art's Gravatar
 Art
 Location: Somewhere, USA
 Member since 22 October 2013
 Member #: 1437
 Postcount: 896

I have measured DC before installing it, and it's 254 Volts measured with a DMM.
I used this example:
http://www.radiomuseum.org/forumdata/users/72/Muiderkring_6E5_typical.jpg
except I left the 1M resistor connected between the pins to
save running an extra wire.

I'm not sure I'm communicating why I think it's almost had it.
It's like it's burned in part before I got it.
It's actually functioning correctly, and the bottom part is the proper brightness.
It's possible it took a hit in the original equipment while in the zero volts position because a transformer has flashed, and left burn marks inside the case.


 
 Return to top of page · Post #: 6 · Written at 10:00:28 AM on 15 May 2014.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5239

I can't really see that being an issue the IT-22 actually puts 540VAC onto pin 4 and 530VAC onto pin 3

It would be interesting to see what you have (photo), but if it is doing everything right, I can't see it being electrically faulty.

Marc


 
 Return to top of page · Post #: 7 · Written at 10:27:51 AM on 15 May 2014.
Wa2ise's avatar
 Location: Oradell, US
 Member since 2 April 2010
 Member #: 643
 Postcount: 830

Seems the phosphor wears out from too many electrons over time. You sometimes see the same thing on CRT TVs and CRT computer monitors that had the same image displayed too long.

QUOTE: It's like it's burned in part before I got it.
It's actually functioning correctly, and the bottom part is the proper brightness.


That's essentially it.


 
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