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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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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 |
#2
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Tektronix 2213 CRT Modification
Steve wrote in
: 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? 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. 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 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 |
#3
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Tektronix 2213 CRT Modification
Thanks so much, that's exactly the info I was looking for.
Best regards, Steve On 14 Jan 2007 22:36:52 GMT, Jim Yanik wrote: Steve wrote in : 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? 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. 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 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 |
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