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465M numerous problems

Hello all,

I currently have on hand a tektronix 465M(military version) that has numerous issues:

  1. Power supply problem, The green power own led blinks and according to the manual it says low line voltage (I have checked the power supplies +32, +5, -5 all check out okay, possible faulty detection circuit?)

  1. problem with the delay time pos pot. doesnt seem to work. (working on currently)

  2. beam shape when beamfinder/trace is displayed, it looks like a oval/ blur no matter how much the controls are adjusted and maybe the CRT is out of alignment?

Did any of you have similar issues with this model. Also would this even be economical to repair considering the amount of problems or are these usually easy fixes. Or should i use this to anchor a boat. Opinions/ help on problems 1 and 3 would be greatly appreciated. Thanks guys.

Reply to
Gavin
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"I have checked the power supplies +32, +5, -5 all check out okay, possible faulty detection circuit?"

Not that I doubt your work, but if you just used a VOM/DVM -- that says nothing about its proper rectification and filtering. First, have very good lighting and a magnifying glass (and a very discriminating eyesight). Why? Once found a resistor with a very small crack -- tested okay (correct resistance) cold -- but then when equipment operated just enough heating caused it to go open.

Electrolytic capacitors, due to the age (and potential field abuse - military, etc.), I examine extremely closely with "old boatanchor" test and radio equipment. Often if I find one or 2 that are questionable -- for my equipment -- I replace them all (preventative for further service bench visits).

gb

Reply to
w9gb

Reply to
w9gb

thanks. ill go look at that. i must have had a brain fart forgetting to check the capacitors first. Oh i had one more question, is it normal for the board to be.....errr sticky?

Reply to
Gavin

use an ESR meter on the caps!

Rod

Reply to
Rodney.Marriott

Gavin wrote in news: snipped-for-privacy@w5g2000hsg.googlegroups.com:

That could be electrolytics LEAKING onto the PCB. That stuff WILL eat thru PCB traces.

also,where you test supplies,you should use a Variac to lower/raise the AC line voltage to see if the supplies still regulate at the low and high ends of the specified input range.

--
Jim Yanik
jyanik
at
kua.net
Reply to
Jim Yanik

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