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Author Topic: TEK 475 Flickers  (Read 3038 times)

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Offline PsychoMasterTopic starter

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TEK 475 Flickers
« on: August 17, 2015, 09:54:31 am »
Hello Folk
When I first switch on my beloved Tektronics 475A on channel one the screen flickers about when you touch the vertical selector dial but settles down after ten minutes warm up so I have not messed with it .It obviously won't sort itself out so any advice would be welcome.
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Offline SaabFAN

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Re: TEK 475 Flickers
« Reply #1 on: August 17, 2015, 10:16:34 am »
Try to get some "Kontakt" Cleaner into the knob. It probably is just a little bit dirty inside.
If that doesn't help, it might be necessary to replace the knob or repair it, because some parts are bent or out of alignment.
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Offline PaulAm

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Re: TEK 475 Flickers
« Reply #2 on: August 17, 2015, 11:35:41 am »
Do not use contact cleaner on the attenuator contacts.  I'm assuming you meant the attenuator since the channel selector controls are push buttons.

The contacts on the Tek cam switches are gold plated and should only be cleaned with a small piece of copier paper soaked in IPA.  They do get dirty over the years.  Cleaning them is a delicate but relatively easy task.  The full procedure is in a thread somewhere.
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Offline SaabFAN

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Re: TEK 475 Flickers
« Reply #3 on: August 17, 2015, 01:24:40 pm »
Is that Kontakt-Cleaner (I have "Kontakt 60" here) bad for gold-plated contacts?
What about Kontakt 200 Oil btw.
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Offline SoundTech-LG

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Re: TEK 475 Flickers
« Reply #4 on: August 17, 2015, 04:21:38 pm »
In that Front End circuit, anything you put in there that does not evaporate completely will change circuit impedances, and alter the characteristics of bandwidth etc. Do you really want to do that?
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Offline PsychoMasterTopic starter

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Re: TEK 475 Flickers
« Reply #5 on: September 20, 2015, 09:14:46 pm »
Hi All
Thanks for the replies , I am so late as the caps went on my old motherboard and I am too tight to get a new one so a awkward repair was needed.I reckon on no more than a clean with alcohol and a good blow as a first attempt.
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