Manna from Heaven: Donated Heathkit SB-650 Digital Display for K1T

Discussion in '"Boat Anchor" & Classic Equipment' started by W7UUU, Jun 4, 2016.

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  1. K7JEM

    K7JEM Ham Member QRZ Page

    You DO know why the transformer hums, don't you?
     
  2. W7UUU

    W7UUU QRZ Lifetime Member #133 Administrator Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    Yes of course.

    I'm quite sure that once back on the chassis there will be enough pressure on the laminations to silence it. Sitting "free air" on the bench, just a touch of my hand and they stop.

    Dave
    W7UUU
     
  3. K7JEM

    K7JEM Ham Member QRZ Page

    Doesn't know the words!
     
    AC8UN and N2EY like this.
  4. W7UUU

    W7UUU QRZ Lifetime Member #133 Administrator Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    Hahahahahahahahahaha!!!!

    Whew! You had me scared that I was missing something that I KNOW Jim would flog me over LOL!!!

    :)

    Dave
    W7UUU
     
  5. W7UUU

    W7UUU QRZ Lifetime Member #133 Administrator Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    Gonna give it a rest for the night.... but I do NOT see a solution - never occurred to me that Nixie tubes, with their very thin wire "pins" would not insert into the "sockets"... Oh Boy, they do NOT want to do that!! 12 pins per tube - I had one break just from it being an original that had been exposed to water (i.e., rust!)

    Tried for almost an hour and couldn't seat a single tube....

    Open to suggestions but this is not looking good....

    Dave
    W7UUU
     
  6. W7UUU

    W7UUU QRZ Lifetime Member #133 Administrator Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    Thinking ... extend all 12 wires from each tube with wire-wrap wire soldered to each "pin" of the tube, plugged into the "socket"...

    Even if I can get the tubes working "floating on wires" I can later anchor them and use the tube light shield to hold in place...

    ??

    Dave
    W7UUU
     
  7. W7UUU

    W7UUU QRZ Lifetime Member #133 Administrator Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    I'm off to bed....

    but I think I have to just give up on this one. I don't see a path that makes any sense.... the flimsy wires on the Nixie tubes simply BREAK OFF without the slightest provocation! I've killed TWO TUBES just with gentle efforts to get them into the "sockets"...

    Breaks my heart.... but I just don't see a path any longer on this one.

    Open to ideas but off to bed.

    169.9 volts HV DC solid as a rock, transformer laminations have gone silent - no more buzzing! ... but no tubes inserted, 2 dead from rotted wires...

    Dave
    W7UUU
     
  8. N2EY

    N2EY Premium Subscriber QRZ Page

    Aw, shoot, Dave, that's a deal-killer because the Nixies are the key to the whole thing. If the pins are so rotted from water exposure that they're snapping off, the project will never be reliable.

    Perhaps the thing to do now is to gather up all the parts and put them in a labeled box. Perhaps replacement parts will become available someday.

    Sorry it came to this. Isee only two solutions:

    1) replacement Nixies, which are pretty rare.

    2) Some other form of Nixie, adapted to the board.

    In "Mr. Carlson's Lab", he built a "digital dial" recently, using Nixies. The ones he used are smaller and he didn;t use sockets, just soldered them to the board. I wonder if they could be adapted?



    Part One.

    73 de Jim, N2EY
     
    Last edited: Sep 3, 2016
  9. W7UUU

    W7UUU QRZ Lifetime Member #133 Administrator Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    Thanks Jim - but I think it may be time to call this one. I actually do have spare Nixies from a couple of IB-101 counters I bought for cheap. But the reality is those machined pins at funky angles are absolutely devilish to insert a Nixie into. The tubes from this original unit can be inserted just fine into the "working SB-650" - as long as the tube wires stay in the plastic forms and as long as the socket holes are perfectly aligned. In other words, I can take one of these original tubes and successfully insert it into the test 650.

    I'll work with it some more this morning, using tubes from one of the IB-101 counters, and see if I can get anywhere.

    But there is going to come a point where I have to say I can't keep diverting all my precious bench time and resources on this device, of which I already have a fully working example sitting right there on the work bench. Sensibility at some point has to take over.... I bet that over at Southgate Radio that the head of engineering would very likely take the same stance, and demand that the bench engineers get back working on other, more productive projects :)

    I'll give it one last go after coffee....

    Dave
    W7UUU
     
  10. N2EY

    N2EY Premium Subscriber QRZ Page

    OK - just don't break anything!

    And other, higher-return projects begging to be done.

    Plus, over time, you may find other solutions. Another SB-650, with different problems, may come your way, so that from the two you can make one good one. (I can imagine there is an SB-650 out there with a good board, but missing most of the chips, with a beat-up cabinet and many parts missing.)

    Plus it is from the too-far-gone units that parts come to keep other units alive.

    One question: Is the dried glue a good dielectric?

    Indeed. There have been projects that turned out to just not be a good idea, and others that required more than the available resources. There have even been projects where it took years to gather all the parts....but when they all showed up.....

    Good luck!

    73 de Jim, N2EY
     

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