Heathkit V-7 Meter Problem?

Discussion in '"Boat Anchor" & Classic Equipment' started by KN4SMF, Jun 4, 2021.

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  1. KN4SMF

    KN4SMF Ham Member QRZ Page

    Today my auction purchase of a 1956-only Heath V-7 VTVM. After a a cursory check out I went ahead and plugged it in, and all seems to work about like I'd expect. I was able to use the 2 meter adjusting knobs and it looks nominal so far as that goes. The unit had never been serviced, as far as I could tell.
    With the power off, however I have a zero adjustment situation. Refer to the attached pictures. They are self explanatory. But the problem is that zero-ing the meter movement with the adjustment screw depends on which position the machine is in. If I sit the machine upright, the adjustment screw won't even go far enough to zero the needle. In these views the window is removed so you can see the needle pivot assembly. Of course it is zeroed here with the faceplate off, because I pushed the adjustment further than the screw adjustment could do.But when I turn the machine on its back it will zero fine. Note the position of the adjustment slot. Then when you turn the machine back upright, the needle falls way below zero. If I were to turn the machine on its right side, the needle will go quite a bit to the right, approaching halfway.
    But like I said, powered up everything seems to work correctly. Do I simply have a flawed meter movement here? Anybody have a remedy? Thank you.
     

    Attached Files:

    Last edited: Jun 4, 2021
  2. K4CCW

    K4CCW Ham Member QRZ Page

    Check out this thread for good info on meter repairs & adjustments. There are many such threads on “meter balance” on ARF - and elsewhere. You’ll need good eyesight and a steady hand with a light touch but it can be done. A watchmaker friend would come in real handy!

    https://www.antiqueradios.com/forums/viewtopic.php?t=157995

    Good luck!
     
    N2EY likes this.
  3. KN4SMF

    KN4SMF Ham Member QRZ Page

    I checked it out alright. And tried it. If only it was that easy. "Slide the weights" it says. Yeah right. Good way to knock the movement off its pivots, which is exactly what happened. I had the dickens of a time getting it back on them. Almost decided to scrap the entire machine and call it a loss. I gave it one last try, and apparently got lucky. I guess the best thing would be to zero the needle while the machine is laying on it back and leave well enough alone. As long as it will electrically zero, and the needle is under the influence of opposite powered poles, then logically it will read accurate in actual use.I dare not fool with it again. I don't know how they mass produce these things, but surely they don't make them by hand, hunkered over a work table with fine hand tools loosing their eyesight and their sanity making them like a little old German watchmaker in 1790.
     
  4. K4CCW

    K4CCW Ham Member QRZ Page

    Yes, after a number of attempts with mixed success I usually only open them up these days if there’s nothing to lose and it’s not working at all anyway.

    Remember, I did say you’d need a steady and and a light touch. Not sure I have either any longer.:)
     
  5. N2EY

    N2EY XML Subscriber QRZ Page

    Well there you go.

    I have two V-7s and they both have exactly the same issue.

    Maybe. You want to check it against a known-good meter.

    Actually, they were all made "by hand". So were practically all vacuum tubes.

    Of course they had the right tools, training, etc., and nobody had much coffee on a workday.

    The word "manufacture" literally means "to make by hand".....

    73 de Jim, N2EY
     
  6. W9GB

    W9GB Ham Member QRZ Page

    Heathkit of the Month #19 , December 2009
    by Bob Eckweiler, AF6C

    The Heath V-7A VTVM and family
    http://www.w6ze.org/Heathkit/Heathkit_019_V7a.pdf

    Static buildup on the meter can cause the meter to appear erratic even when the device is off and the meter is in good shape.
    A little dishwater detergent wiped on the meter face should clear it up. Be sure the meter returns to the same point each time it is deflected and that the manual meter zero control can bring the pointer to the meter scale zero mark.
    If you can peek inside the unit, make sure the battery has not leaked and corroded the cup or spring. the positive contact is just a #6-32 bolt and can be replaced.

    ===
    HOLLOW STATE NEWSLETTER
    “For lovers of vacuum tube radios”

    THE HEATH VACUUM TUBE VOLTMETERS
    Issue # 44 , Spring 1998
    The Universal Test Instrument and a Piece of Electronic History
    by Kurt H. Miska, N8WGW
    This article originally appeared in Electric Radio magazine,
    under the title "The Heath Vacuum Tube Voltmeters," October 1994, No. 66, p. 28.
    http://www.navy-radio.com/manuals/hsn/hsn-issue 44.pdf
     
    Last edited: Jun 5, 2021
  7. KN4SMF

    KN4SMF Ham Member QRZ Page

    Well, it's a loss after all. I got everything worked out and getting ready to button it up, and the needle fractured up to bits like a hundred year old dead pine needle, Apparently it had turned to 100% pure oxidaton from the inside out and outside in.
     
  8. N2EY

    N2EY XML Subscriber QRZ Page

    Oh well....

    Please don't discard it. Sell it or keep it for parts - there's some unobtanium stuff in a V-7.
     
  9. KN4SMF

    KN4SMF Ham Member QRZ Page

    I just stupidly paid $29 for it plus shipping for a grand total of $42 that I really didn't have money to spend. Makes me sick. Now I want it out of here so I can try to heal from my stupidity. Know what else I've been noticing? Looking at them on ebay and elsewhere, a lot of them have needles sitting way below zero. I bet the needles in all of them are powder, ready to disintegrate with the slightest touch. Maybe new the balancing was correct. But its not any more. Just because its Heathkit, don't go ga-ga. That's my new motto. They DID make some real junk, like any company.
     
  10. N7EKU

    N7EKU Ham Member QRZ Page

    Hi,

    The needles were painted nicely when new, however by now much of it has oxidized and flaked off. So now they weigh less and the unit is out of balance.

    I just re-balanced one last month. No coffee and both feet on the ground! Once I had it close, I found it easiest to make the final adjustments by adding small amounts of paint on the counterbalances where needed. It's so nice to have it balanced in both the horizontal and vertical positions.

    73
     

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