EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: nrgeek on January 27, 2012, 12:26:29 am
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Ive got a 475M .. I cant get the red var on the A and B time/div knob to click off by turning to the right .. tried left in case was different than the channel 1 and 2 var knobs .
Nope ..calibration light is still on .. no click .. anyone here that is very familiar with this model scope care to chime in on a solution !?
Much appreciation in advance ! ;D
Sean
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Well it sounds to me like there is something wrong "Mechanically" with the pot. I would open it up and see whether or not you can see movement at the pot at all... the reason i say this is that you cant feel the click... makes me wonder about the pot itself. They do sell replacements for these.. i will have to dig around to where i saw one recently.
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Yea I just found one myself .. and its here in tn Qservice they sell Scarce and obsolete parts to restore your old test equipment http://www.qservice.tv (http://www.qservice.tv) 15.00 for new or 12 fir used tested.. I will spend the other 3 bucks :)
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I have my 475 in bits, if you need photos just ask. I have just looked and it's driven by a muff coupling with Allen screws in to lock the long shaft to the input shaft of the pot. have they come a little loose? If not I can't see what else it could be other than a mechanically defective pot itself.
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I took the case off , this morning , and its not the pot part number I thought it was .. the only thing other than finding one .. and looks like it may be tough .. is to take out set screws ( loosen ) .. take of the pot . of course marking the position, and seeing if it turns off by hand .. if not gonna have to find part number 311-1793-00 and so far on the net .. its a no go on that part number including ebay .. someone has got one sitting around on a shelf or in a dead machine .. I just gotta hook up with that person :)
Attached a pic of the pot in case anyone curious lol (http://img543.imageshack.us/img543/649/p1280280.th.jpg) (http://imageshack.us/photo/my-images/543/p1280280.jpg/)
and the red var knob that is attached to that pot (http://img855.imageshack.us/img855/4788/p1280284.th.jpg) (http://imageshack.us/photo/my-images/855/p1280284.jpg/)
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I finally found one .. took post on TekScopes yahoo group to locate someone that had a spare they would part with .
:D
Ashley over at http://www.kiss-electronics.com/ (http://www.kiss-electronics.com/) Cornelius, Oregon hooked me up with what I needed! They specialize in repair and refurb of old boat anchor test equipment
Thank you Ashley ..
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That's awesome!
Nice to know you can still get parts for these things. I got pretty lucky on mine.. it works great but you never know what the future holds.. spare parts is a good thing!
I'm just getting back into it as well so im looking forward to learning as much as I can!