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My new old Precision Tube Tester

Discussion in 'General Electronics Discussion' started by tryppyr, Feb 9, 2014.

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  1. tryppyr

    tryppyr

    228
    1
    Oct 22, 2013
    I have dozens of old tube type radios that I have lately been thinking about repairing. What I didn't have, until yesterday, was a means to effectively test the tubes short of simply turning the radio on and seeing what happened. Well, now I do.

    I haven't tested the tester yet, beyond simply plugging it in and knowing the light lights up and the needle centers on the dial... but hey, if there is a problem we'll fix that first.

    This unit came with the booklets of tube test data, as well as an adapter used to connect smaller tubes.

    - Greg
     

    Attached Files:

  2. tryppyr

    tryppyr

    228
    1
    Oct 22, 2013
    Ran a few tests today. Because I don't know if the tubes are good or not, it's hard to say if the results are meaningful. However, it seems to me that the meter ALWAYS reads exactly in the middle (the Weak band) and I would expect some variance. The Short light came on for four out of the five tubes, so I suspect it works.

    Not much else to go on at the moment.
     
  3. shrtrnd

    shrtrnd

    3,749
    482
    Jan 15, 2010
    Did you open it up?
    That's a pretty old model. It might run on tubes itself. I'd check for the parts condition first.
    then clean-up any electrical contacts that look tarnished or need attention.
    The manual should give you a basic initial turn-on operational check.
    (The analog meter goes full scale, or something similar).
    There are a lot of individual checks tube testers are capable of. They could all be fine,
    or some will or won't read right. If it runs on tubes, or has high heat observable damage
    to components, I'd look at that first.
     
  4. tryppyr

    tryppyr

    228
    1
    Oct 22, 2013
    I did open it up yesterday. It has only one tube inside (an 80). Otherwise, all solid state save for the bulbs.

    It didn't actually come with an owners manual, but I found a PDF of one online and downloaded it. It contains a rudimentary diagram. I also found a schematic.
     
  5. GonzoEngineer

    GonzoEngineer

    321
    2
    Dec 2, 2011
    I have two of those, and the only tube inside is the Rectifier for the DC Supply.

    If you need schematics or parts, let me know.
     
  6. tryppyr

    tryppyr

    228
    1
    Oct 22, 2013
    Thanks. I just read the manual, and now have a sense for what I was doing wrong yesterday, so I'll try the tube tests again tonight. I'm guessing everything is fine with the unit. It was the operator that needed repairs. ;)
     
  7. tryppyr

    tryppyr

    228
    1
    Oct 22, 2013
  8. GonzoEngineer

    GonzoEngineer

    321
    2
    Dec 2, 2011
    Watch out for mods made to your tube tester. It was common for users to make modifications for newer tubes. It can really be a bitch if you don't know what they did.
    Having an unmodified 912 is premium.

    Like I said, if you need any parts, let me know.

    I will also check my tube data updates, and if I have later ones will also post them
    here.

    Those things were real workhorses, and a good bit of history goes with them.
     
  9. tryppyr

    tryppyr

    228
    1
    Oct 22, 2013
    This one does have a 9-pin socket installed (I'm guessing not factory installed) and it came with the G109 adapter, so I presume that means they also added a resistor to insure the voltage to the 9-pin would be correct.

    Thanks. I will let you know if I get hung up.
     
  10. tryppyr

    tryppyr

    228
    1
    Oct 22, 2013
    Good news! Now that I know how to use the 912 I find that is seems to be working correctly!
     
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