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Tektronix 2445B Scope Fault

Discussion in 'Troubleshooting and Repair' started by Bazzatron, Aug 12, 2010.

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  1. Bazzatron

    Bazzatron

    5
    0
    Aug 12, 2010
    Gooday to all out there!

    This is my first post on your forum so be gentle with me.

    I have a Tektronix 2445B scope that shows "Test 05 Fail 44" on startup
    "Press A/B Trig To Clear" which when pressed all seems well.

    What is this error message all about?
    Will it prove fatal and can it be fixed if so how?

    Thanks for reading hope you can help

    Regards Bazzatron
    Western Australia.












    '
     
  2. shrtrnd

    shrtrnd

    3,795
    503
    Jan 15, 2010
    The "press A/B trig to Clear" automatically comes up when any one of the power-up test fails, ....that's normal, it's working correctly.
    When you power-up, scope runs it's own internal test routine, one test failed, giving you the above notification.
    Routine Test #05 is a test on the main board.
    The error code is telling you the Positive Level is Too Positive.
    (I'm a little busy here right now, when I've got some time, I'll check into the solution for this error, and post another reply with additional info.)
     
  3. shrtrnd

    shrtrnd

    3,795
    503
    Jan 15, 2010
    Ok, first I'll tell you probably what you want to know:
    Your error code is not fatal, and you can keep using the scope just the way it is with no problems.
    Now I'll tell you what's going on with it, in case you're interested, but I STRONGLY suggest you don't do anything about it yourself. This is just for your information only.
    The test that generated the error code detected a high peak on the LEVEL of your line trigger signal. There isn't any potentiometer to adjust THAT, it's all done in the electronics. What a repair shop would do, is run the 'self-calibration' for the instrument, (DON'T do this yourself). The repairman would remove a jumper inside the instrument to enable the self calibration, and adjust horizonal, vertical, and trace pots to set the scope levels. But you ABSOLUTELY cannot do that without a lab standard calibrated DC voltage source. If you adjusted anything without an exact DC cal standard, you'd screw the scope alignment royally, and wouldn't know where you were at with it. I suppose you didn't NEED to know that, but since you're on this site, asking questions, I thought you might LIKE to know.
    You're fine with the scope the way it is, it's just telling you the trigger level is a little too positive (but don't touch it yourself).
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,473
    2,819
    Jan 21, 2010
    G'day from a sandgroper.
     
  5. Bazzatron

    Bazzatron

    5
    0
    Aug 12, 2010
    Tek 2445B Fault

    Gooday all,

    Thankyou for your prompt reply to my questions regarding the startup fault displays.

    Whew! You have certainly put my mind to rest I had a suspicion that nasty things
    were about to happen.

    I am well aware that this scope has a few years on its clock and could and probably will develop faults, to this end i have downloaded service and operators manuals but they are
    not always clear as to what if any procedures need to be done.
    Is there any way to read from the scope its time-on-in-use data?
    It would be interesting to know how many hours its done etc.

    Well rest assured i will be a good boy and leave well enough alone in this instance!


    Thanks again

    Barry.
     
  6. shrtrnd

    shrtrnd

    3,795
    503
    Jan 15, 2010
    I don't know of any way to find out actual hours on the scope.
    Mfgr says it was built for 2,000 hours of no-problem use (just for your info).
    As always, recommended calibration from the mfgr is once a year.
    But Calibration is always expensive. And your problem is not a serious one.
    In your case, I'd run it until you start having other problems, then consider calibration.
    Just my opinion.
     
  7. Bazzatron

    Bazzatron

    5
    0
    Aug 12, 2010
    Thanks for your efforts regarding the info for finding Hours of use.

    I will read through the service and operators manuals and if i find
    a reference to reading hours of use i will post the results here.

    Thanks again everyone
    Regards from Down Under
    Bazzatron
     
  8. Bazzatron

    Bazzatron

    5
    0
    Aug 12, 2010
    Tektronics 2445B Hours-Run & Power-Cycles

    Sucess!!
    I have found the procedure to show the hours of use and power cycle count.

    Using the 2445B/2455B/2465B Oscilloscope And Options Operators Manual
    070-6860-00

    Appendix A

    Page177

    Extended Functions With Diagnostic Exercisers

    Exer 05
    Display Operating Time And Power Cycle Count
    Is the Exer to use as per the procedure on page 177
    And page 178 shows how Exer 05 displays the data when it is run.


    Whew! these tektronix people sure know how to write a tech manual
    all the info is there IF you can find it!

    Well guys hope that info will be of value to others wanting to know how many hours run and power on cycles their 2445B scope has done and to keep track of times between calibrations.

    Regards
    And Thanks again for all your valued input to my questions

    Bazzatron
    WA
     
    Last edited: Aug 13, 2010
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,473
    2,819
    Jan 21, 2010
    So, come on, how many operating hours does it have on it?
     
  10. Bazzatron

    Bazzatron

    5
    0
    Aug 12, 2010
    scope hours and on off cycles

    Sorry about the delay in reply

    I ran the routine and got 29,276 total hours on and 3,152 on-off cycles.

    works out to approx 3.36 years of use since built

    assuming build date was 1989 or 1990 thats not bad

    3.36 years of use in 20 years

    Am having further issues now with inability to reduce intensity
    will investigate and advise when i find the problem
    i suspect bad caps etc :D
     
  11. Mark Allen

    Mark Allen

    1
    0
    Oct 2, 2010
    I had exactly the same problem with a 2445B yesterday! Check your -8 volt and - 5 volt supplies... mine were low. DC voltage test point is the empty 14 pin IC socket on the main board near the sequencer chip. Both those - supplies were low and I found a100uf cap had changed value and was only about 62uf. This was the input cap on the -8 volt which is a voltage doubler circuit. Replacing the caps in the -8 and -5 volt supplies restored normal operation and eliminated the error at start up. NOw all voltages are well within normal tolerance.

    I too have a brightness control problem and the verticle centering pots seem to have a strange stiction effect to them. Whereas you move the pot then a short time later the change takes place. Brightness is erratic but once set stays where you put it. The problem at least with miine is not the Z axis hybrid or the display sequencer chip. I pulled both from a working unit and subed them in. I suspect more bad caps somewhere on the main board. The other problem is that I only have the 2445 manual... could only find that one on the net and the potentiometer arrangement on the B model seems slightly different. So ordered the "B" manual from Artek MEdia and am waiting.
     
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