Hex keys for removing Tektronix rotary knobs

Discussion in 'General Electronics Chat' started by hrs, Mar 5, 2016.

  1. hrs

    Thread Starter Member

    Jun 13, 2014
    82
    7
    Hi,

    I have a Tektronix 475A oscilloscope. All of the rotary knobs are fastened to their shafts in the radial direction with hex screws. My metric set of hex keys goes down to 1.5mm which is just a pinch too small so those are probably 1/16". All hex screws appear to be the same size except for the one in the "Delay time position" knob. This one is smaller. Could this one be 0.05"?

    Some of the screws are not so hex anymore, as if they've seen too much abuse from metric keys that don't quite fit. I'd like to replace some or all of them. Does anyone know the exact designation of these screws, thread type etc?

    I'm not so versed in US customary units and associated tools, threads etc. so any help would be appreciated.
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,548
    2,373
    Last edited: Mar 5, 2016
  3. dl324

    Distinguished Member

    Mar 30, 2015
    3,244
    622
    They're mostly 1/16" hex on my 466. Time delay is smaller and I didn't have the correct size handy.

    I checked some 7000 series plug-ins and the set screws are the same size, so you could used parts from donor plug-ins.
     
  4. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,694
    904
    5-40 has become uncommon in regular hardware stores and big-box stores. 4-40 is much more common, but it cannot be substituted well. McMaster Carr in the US has them: http://www.mcmaster.com/#set-screws/=11eqmjw

    Not sure whether it ships internationally.

    John
     
    Hypatia's Protege likes this.
  5. ian field

    Distinguished Member

    Oct 27, 2012
    4,415
    784
    AFAIK: the grub screws on my 465 are fractional inch.

    Metric keys will sometimes work if the screw isn't tight, but an improper fit causes wear - and you *REALLY* don't want that!
     
    Hypatia's Protege likes this.
  6. hrs

    Thread Starter Member

    Jun 13, 2014
    82
    7
    Excellent, thanks! It seems like the required Allen keys and set screws are available on Ebay and ship to me.

    I think the previous owner(s) found that out too. But I can probably glue in a small rod with some loctite and get it out.
     
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,548
    2,373
    I confirmed it on my 'scope they are as in post #2.
    Max.
     
  8. ian field

    Distinguished Member

    Oct 27, 2012
    4,415
    784
    Just make sure none of the glue runs into the thread!!!
     
Loading...