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TEK 465 Scope - Power Supply Voltages

Discussion in 'Electronic Repair' started by Guest, Feb 17, 2007.

  1. Guest

    Guest Guest

    I left my 465 on for a few days and now there is no trace. All voltages are
    correct except 2KV, 95V and 32V Unreg. The 32V blows the .25 amp fuse. Any
    suggestions?
    Thank you,
    Dale
     
  2. DaveM

    DaveM Guest


    I'm looking at the 465 and the 465B manual, and I don't see any of these low
    voltage supplies. The only unregulated outputs are +120V and the unregulated
    source for the +55V regulated output (actually +78V) and +15V unregulated. .
    There is a +110 regulated output, but no 95V output.
    Which version of the 465 do you have? (465/465A/465B)
    --
    Dave M
    MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
    address)

    Some days you're the dog, some days the hydrant.
     
  3. Jim Yanik

    Jim Yanik Guest

    It's a 465M,not truly a *465*. It's more like a 455A2B2 with wider BW.

    The 32V-unreg runs the HV,he probably has a bad multiplier or CRT.
     
  4. Guest

    Guest Guest

    Sorry,it is a 465M.
    Dale
     
  5. Guest

    Guest Guest

    Jim,
    What do you suggest for the next trouble shooting step? Unplug the CRT? or?
    Thanks,
    Dale
     
  6. Jamie

    Jamie Guest

    If you have a HV-Probe, stick it on the Anode lead.
    I don't know what the HV is suppose to be on that unit
    how ever, the last one i looked at was aprox 12k.
    I had to replace a trippler in old MIll Spec scope
    made by Dumont years ago. i still have the scope at
    it works nicely.. 60 Mhz..
    I ended up making a new trippler using the old
    case that was in there. because i too, left the
    scope on for a couple of days and came back to
    find the fuse blown out.
    I used a dermal tool to remove all the old contents.
    used some common HV diodes and got some caps together.
    soldered them together on a predilled board with no
    foil. laid it in the case, and used HV putty layers
    at a time with a heat gun to fill the majority of it.
    then top it off using silicone.
    It works perfect..

    What i did to test it, i disconnected the HV coil
    lead going to the trippler. did a HV ac test from there.
     
  7. Jim Yanik

    Jim Yanik Guest

    disconnect the HV drive to the multiplier.The 95V should come up and the
    32Vunreg fuse should not blow.

    Do you have a 465M service manual?
     
  8. Guest

    Guest Guest

    Thanks Jim. Yes, I have the manual on CD.
    Dale
     
  9. Guest

    Guest Guest

    Jim,
    I disconnected the HV drive at pin 10 of the transformer where it is
    connected to the HV multiplier. Fuse still blows. What next?
    Dale
     
  10. This isn't the usual shorted tantalum cap problem? :)

    --- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
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  11. Jim Yanik

    Jim Yanik Guest

    Was that the wire from a post on the side of the multiplier to a separate
    post on the xfmr?
    then the HV osc xstr is probably failed.

    time to troubleshoot.

    BTW,there's an excellent circuit description in the service manual that
    tells how the circuits work,I always referred back to them,I consider them
    invaluable.I hope they included it on your CDROM.
     
  12. dale

    dale Guest

    Jim,
    Yes, the lead I disconnected was from a post on the multiplier to a separate
    post on the xfmr. Sam mentions a tantalum cap. Is there a certain one that I
    should check? If the osc transistor failed would it load down the supplies?
    I'll be on travel for a few days and unable to do any more testing until
    Thursday pm. Can I write you at kua.net?
    Thanks,
    Dale
     
  13. Jim Yanik

    Jim Yanik Guest

    Don't you think a shorted xstr would blow the 32Vunreg fuse?
    FIRST,I suggest you READ THE CIRCUIT DESCRIPTION for the HV oscillator.
    Then you should know how to troubleshoot it. I'm not going to tell you
    "check this,then this ,then this".....ad infinitum.

    I also do not have any TEK manuals to reference,I work from memory.
     
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