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Tektronix 2246

Discussion in 'Electronic Repair' started by [email protected], Apr 17, 2006.

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  1. Guest

    Traces and readout intensity are sometime very brighter than usual.
    When this occurs two out of four neon bulbs located in HV "module"
    flashes. These two bulbs are connected at pins 2 & 3 of CRT. I'm also
    looking for the tech manual.
    Any ideas?

    Thks,
    Daniel
     
  2. Guest

    You'll have to wait until Jim Yanik comes around for comfiration, but I
    suspect the CRT.

    Actually, that is not bad luck, IIRC there are some very hard to get
    ICs for Tektronix scopes. Think it was the horizontal amp. Your problem
    has nothing to do with that, so hopefully either you have ICs for
    another scope or can find a CRT for yours.

    Once sure of the problem, ESI in Cleveland OH has alot of Tek stuff.
    You might try Skycraft in Orlando FL but they don't have as much, or
    didn't last time I was there. Other than that there is always eBay.
    There are other places, I just don't know of them.

    Good luck with it.

    JURB
     
  3. Guest

    Thanks for reply. Glad to hear about availability of TEK CRT's. In the
    meantime of Jim advice's I'll use my 2213. Not the same feeling,
    definitively.

    Daniel
     
  4. Jim Yanik

    Jim Yanik Guest

    wrote in
    TEK puts a couple of neon lamps between the CRT cathode and grid to limit
    the voltage difference between them to less than ~130v to protect the
    CRT;pins 2,3 are CRT cathode and grid.(P1,14 are filaments)

    I do not have access to any TEK manuals anymore.
     
  5. Jim Yanik

    Jim Yanik Guest

    wrote in
    I have a 2213,too.
    Nice scope,built it myself,from boards and parts other techs didn't fix.

    [plus a few purchased parts to complete the job,and a FREE non-salable CRT
    thanks to Vern Isaacs who ran CRT manufacturing at TEK.]
     
  6. Jim Yanik

    Jim Yanik Guest

    wrote in
    BTW,the DC restorer diodes could be breaking down intermittently under HV.
    They're part of the CRT brightness circuit.
     

  7. That reminds me of the old Johnny Cash song, "I got it one piece at a
    time". ;-)

    <http://www.cowboylyrics.com/lyrics/cash-johnny/one-piece-at-a-time-2214.html>
     
  8. Jim Yanik

    Jim Yanik Guest

    The first TEK scope I built from old boards was a 5 Mhz 221 mini-scope,but
    it had problems in the 4 layer PCBs,I had to jumper too many runs,so I
    traded it for boards for my 2213. It's CRT was too small for much
    use,anyways.
     
  9. What's the next model, the 321? I still have one of those that more or
    less works (or at least it did the last time I tried it a couple years
    ago). Some of the design of that is strange. I have to power cycle mine
    a few times before the trace appears, and only at full brightness. I think
    I concluded it was fault in the CRT because everything else checked out.

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  10. Jim Yanik

    Jim Yanik Guest

    An entirely different class.
    The 200 series were a group of handheld,battery-powered scopes with really
    small CRTs.

    The 300 series (after the 321) were from Sony-TEK.
    The 321 was first sold in 1960,BTW.It was TEK's first solid-state scope(and
    also battery-powered).
    The 211,the first 200 series scope,came into being in 1972.
     
  11. I recommend you check for a couple of failure possibilities:

    First: DC restorer diodes might be damaged, as Jim says.
    If ok, check for cold solder joints near insity pot (cracked due to
    mechanical stess, cold solder, etc.9.
    If ok: I suspect CRT (had this 3 times), but CRT seldom fails to my
    experience in the 2213/2215 sereis scopes.


    hth,
    Andreas
     
  12. The 221 etc. series scopes still run fine nowadays. You need a calm
    hand and a lot of experience to keep them healthy. But in the end, for
    using in field service at a customer site, I like these small scopes.
    The BW is low (0.5 up to 1 MHz, depending on model). But most times
    enough for the things I have to do in field: get a quick impression of
    where the fault is, these scopes are real helpful.

    The battery and the plastic molded case gives my most time problems
    when I get these units for repair.

    Personally, the 213 with the integrated DMM is what I enjoy most. It's
    a good combination, and still useful in 99% of my service work.
    If you take a little bit of care, and handle these analog scopes well,
    they last real long.

    Andreas
     
  13. Guest

    TEK2246.

    Thanks to all for inputs.

    I have made a cleaning and resoldering job around diodes and high
    voltage caps under the HV plastic covers. I think it was never cleaned
    since 20 years as it was a quite dirty area. Now trace and readout are
    stable again and the neon bulbs doesn't flashes anymore. Maybe it's
    fixed. It's working fine since two days now.

    BTW as I do not have the diagrams are those diodes (MSC 152-0242-00632)
    the DC restorer one's?

    Daniel
     
  14. Jim Yanik

    Jim Yanik Guest

    221 was 5 Mhz,
    213=1 Mhz,
    211-212-214=500 Khz
    The plastic pins in both case halves are important,they retain the circuit
    board's position,keeps the interconnect pins from spreading the receptacles
    open and the tiny leaf spring from falling out and shorting things.They
    caused a few meltdowns,with those NiCds.
    213 and 221 were the best of the 200 series.
     
  15. Jim Yanik

    Jim Yanik Guest

    wrote in
    the proper TEK part number would be 152-0242-00,and they would be the DC
    restorer diodes. I don't have the specs or cross references.
     
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