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Cardmatic update & ?

Discussion in 'Electronic Repair' started by Henry Kolesnik, Feb 4, 2004.

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  1. I've got one of my Hickok LS 15874 L2 Cardmatics going. I cleaned, lubed
    and realigned the switch matrix as well as other switches and also found a
    cold solder joint from a previous repair. About 100 of the switch matrix
    pins had what looked like old paper capacitor wax on them, very sticky! I
    took all the pins out, cleaned each one and the sockets. (An ultrasonic
    cleaner would have been nice.) It took several attempts to get the
    clearance correct, since the jam nut moved but I finally figured out a
    system. Now it appears to test tubes just fine but it still has one problem
    that escapes me and wonder if anyone would have any ideas. It responds per
    the manual to all test cards except card 9, Gm, Low Ib. About half the time
    card 9 will kick power off and I'm guessing it's because the meter kicks
    backwards below zero when button 2 is pressed When it doesn't I can adjust
    Low Ib per the manual and seems to work fine. However sometimes the meter
    needle doesn't go below zero enough to kick the power out but when this
    happens the Ib control has no effect! Any ides or tips appreciated.

    73
    hank wd5jfr
     
  2. Chris Haedt

    Chris Haedt Guest

    I told you if you moved those jam nuts at the bottom of the reader
    you'd have fun! Have you replaced ALL of the electrolytic caps? Caps
    could be the cause of what you are seeing. Plus--seems like there is
    also an adjustment for the sensitivity of the circuit breaker in the
    machine. There are something like 50+ cards to calibrate the
    machine--went through all of those?

    Chris
     
  3. Chris
    I am guilty of not heeding your advice on the jam nut but it was not
    intentional mistake, it was the result of several attempts to get the parts
    back together. But a dope slap imigh tbe in order. I'm very impressed with
    engineering, design, and manufacture of the switch. Except for alignment, I
    don't see any need for improvements. I'd guess the facctory had a jig for
    aligment. I used a 13/64" allen wrench as a "feeler guage" after I
    determined what clearance was necessary to make sure all pins were out and
    how much they needed to go down so the female contacts would snap in the
    grooves of the pins. It took hours but the next time it will be quicker!
    As far as the 54 test cards, I can't get proper readings on 1 thru 5 as
    my Cal. Cell is dead, or Card 9 but the rest are in spec! For the
    calibration cell Alan Douglas's book shows a 4.7 volt Zener while the
    USM-118 website has a 5.1 volt Zener and I'm trying to find out if the
    difference is important.. I think I may attempt to recharge the Cal. Cell
    mercury battery with my constant current source and see what happens.
    The tube socket voltage and resistance readings pretty much agree with
    the data in the manual. All the electrolytics pass on my Dick Smith ESR
    meter.. I'm a rifleman not a shotgunner when it come to caps unless there
    is evidence that most of the caps are suxpect because of manufacturer or
    age. Besides, I like to know what component caused the fault. Next I
    think I'll let the unit hot soak for 24 hours and look at it with a scope.
    It passes the breaker tests fine so I don't think relay needs
    adjustment. Since the Card 9 problem is not always repeatable it's difficult
    to pinpoint. What happens on Card 9 is sometimes the meter tries to go
    below zero and sometimes it kicks the unit off. I'm still trying to figure
    out how this Gm balance bridge circuit works. I've colored a set of
    schematics with Card 9 switches activiated and trying to get thru the maze
    to see if I can pinpoint the fault.
    All that being said the Cardmatic is one hell of a design for a tube
    checker! I've got to get it going because I hve hundreds of tubes to check!
    Any all tips appreciated.
    73
    hank wd5jfr
     
  4. Chuck Harris

    Chuck Harris Guest

    Don't! At best, it won't work, at worst, it will explode. The mercury
    cell is a one way reaction. It cannot be reversed.

    Been there, tried that, blew it up!

    -Chuck Harris
     
  5. It's fixed, a new day respite helps. Previously I noticed that the
    component board had been removed at some time becasue I could see signs of
    resoldered wires on the non-component side. (At that time I found a cold
    solder joint on R231.) I thought perhaps a wire had come off or someone
    transposed some. Being lazy I got the high intensity light out and thought
    I could see if there was a problem without taking the board out, there's
    only 4 screws! But before doing that I thought I'd recheck the 10K ohm Gm
    bridge resistors, pot and as I was connecting my Fluke to the10K resistor
    lead I could see it was wrapped around the post but not soldered, same for
    all of them. Eureka and happiness, good light helps. I took a pix and posted
    it at alt.binaries.pictures.radio. I soldered 4 ends and now it works like
    a champ and checks a known good 12AX7 as good. No more meter slamming
    backwards on Card 9 or power kick off and the Lo Gm pot works per spec.
    After more careful inspection I could see where others have tried to repair
    this one because I could see other signs of soldering and component
    replacements, some not so good. Since it was like this from the factory,
    it had to have been continually intermittent and became a waster of gravity.
    Anyway I'll be it didn't get much use and I think the condition of the
    switch matrix with all the waxy stuff was becasue it was sprayed trying to
    solve the no solder problem. This one is Serial No. 703 so if you have one
    near that you might want to check R 402, 403, 404, and 406 for no solder!
    73
    hank wd5jfr
     
  6. Which just undescores what I've been telling my techs all
    along. VERIFY everything before you start flogging the
    assembly.

    Jeff
     
  7. In this case the "assembler" needed flogging!

    hank wd5jfr
     
  8. This was a very interesting post Henry, I have one of these and it seems to
    be working OK. I have everything except the cal cell is dead. I would like
    to see a pic of those jam nuts that you shouldn't touch if possible as I
    thought about cleaning the card reader.
     
  9. Alan Douglas

    Alan Douglas Guest

    Hi,
    The calibration cell simply verifies that the meter is 100
    microamps and a total of 250 ohms. And it contains the limit resistors
    for the leakage test. I wouldn't worry about it.

    Incidentally I wouldn't use any silicone lubricants on the
    card-reader pins. While the original organic grease has stiffened with
    time and needed to be replaced, it was probably carefully selected to
    do its job. On the Cardmatics I've repaired, I've used a grease
    originally supplied to General Radio by Oak, but I have no idea where
    to get more of it. It was described to me by the GR engineer who gave
    me some, as "Beacon M325" grease.

    73, Alan
     
  10. For noisy TV tuners back in the 1960s when I was working in a Radio and TV
    shop we used Lubriplate white grease that came in a small black and grey
    tube that resembled travel toothpaste.We sprayed the wafer switch in the
    tuner, rotated several times and then applied a light coating of Lubrplate
    with a small stick and rotated several more times. On turret tuners we
    cleaned the pads and wipers with contact cleaner on a Qtip and then applied
    Lubriplate. This was in Norman, Okla where the humidity played havoc with
    tuners making them intermittent and after the treatment we never had call
    backs. Somewhere I have a partial tube of this stuff but haven't located it
    as yet, so I used DeOxit on the Hickok switch matirix but would have used
    Lubriplate if I found it. After about more than 20 moves there's lots of
    possiblities where it is. Two local auto parts stores didn't have anything
    but silicone grease which I haven't used except as a heat transfer aid on
    power transistor heart sinks. I think that Lubriplate would be a good
    lubricant/protector unless there's something better that I don't know about.
    I'm guessing that there's something better after 40 yeats and would be
    interested in what users have used>
    Now to repair number 2!
    73
    hank wd5jfr
     
  11. Jim Adney

    Jim Adney Guest

    Very nice going, but I'm not able to see your photos (server doesn't
    have that newsgroup) so could you describe for the rest of us what
    this connection looked like?

    thanks,

    -
     
  12. Lou
    Under the black cover over the matrix swtich there are 3 black bakelite
    slabs (3.5" X 4.5" X ~1/4") with 187 holes sandwiching 185 pins. With the
    black cover removed (2 screws) and the card plunger pushed in and you'll
    see that the sandwich "floats" on four 8-32 threaded posts. Each of these
    posts has 2 nuts sandwiching the slab sandwich. The position of the lower
    4 nuts (I called these jam nuts) determines how far in the 185 pins go into
    their female counterpart where there is no hole in the card. If there's a
    hole in the card the pins must not make contact with their female
    counterpart, and this clearance is about the thickness of a dime. In
    addtion all these jam nuts must be on the same plane so that the sandwich
    is orthagonal and will not bind so it can move smoothly.
    A pix would have been easier but the batteries are being charged. Let me
    know if you still need a pix.
    73
    hank wd5jfr
     
  13. Thanks Henry, I see what you are saying. The pins come up to about an 1/8'
    from the top of the plate. One thing I just noticed, there is no pin in the
    17A position, bottom left corner spot. I wonder if mine is missing or it
    was made that way?
     
  14. There's 187 holes with 185 contact pins. A17 has a threaded guide post that
    sets the gap (about a dime) between the two female connectors that the pins
    connect when there's no hole in the card. H17 doesn't have a pin nor does
    it have the lower female solder connection, I guess they didn't need it.
    Perhaps when someone has or will find a need for the 186th pin we'll have to
    find an extra pin and a lower female contact and a place to route and
    terminate the wires.
    73
    hank wd5jfr
     
  15. Jim Adney

    Jim Adney Guest

    Thanks to those who sent photos. Those "posts" are more commonly
    called "turrets", I believe.

    Finding these missed solder joints must have given you a VERY well
    deserved good feeling. Congratulations.

    -
     
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