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Tektronix 2213 CRT Modification

I have a great Tek 2213 that was purchased form a TV station. The scope is in great condition, but CRT is very dim. IIRC, I've read that these scopes had a slightly high filament voltage resulting in short CRT life, and there was a mod that Tek did to fix this problem by removing a few turns on the XFMR. Is this right? I also remember someone saying that there was a marking on the back of the scope or the xfmr if they had been modified. Well, I found a replacement CRT with plenty of life left in it, but I don't want it to fail prematurely again. Is this a user modification, or is it pretty lenghty? Any info on this subject appreciated.

Thanks, Steve

Reply to
Steve
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Steve wrote in news: snipped-for-privacy@4ax.com:

Yes;a half-turn was removed from the T940 inverter xfmr's HV filament winding,the brown wire at the top of the bobbin.

You have to re-adjust the CRT grid bias after the mod is done.

CRT filament mod 2213 S/N range; B010100-B029389,200001-203411

Modded scopes should have a Tektronix ID Number label on the rear somewhere;M50226 is the Mod number.

S/N's B027000-B030000,202500-203411 should be checked for prior modification BEFORE implementing the mod.

IIRC,inverter xfmr's with an -01 suffix will already have the mod.

from my schematic peniclled-in notes,CRT fil voltage ;

**measure disconnected from PCB!!** (true-RMS meter)

unmodded 7-7.3 VRMS modded 6.1-6.4 VRMS

2X mod 4.4-4.6 VRMS (2X= mod mistakenly done twice) 
--
Jim Yanik
jyanik
at
kua.net
Reply to
Jim Yanik

Thanks so much, that's exactly the info I was looking for.

Best regards, Steve

Reply to
Steve

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