HelloDirect Headset Switch Cleanout

The headset / phone switch in my ancient HelloDirect phone headset became increasingly intermittent and finally stopped switching at all, so I tore the thing apart. It has two snap latches on each side in addition to the single screw in the bottom:

HelloDirect headset interface - top interior

HelloDirect headset interface - top interior

The 4PDT switch just to this side of the volume drum can’t be taken off the board without unsoldering all 12 terminals and two case anchors, so I just eased some DeOxit Red into the openings and vigorously exercised it. That seems to have done the trick.

I cleaned out a bunch of fuzz and a spider husk while the hood was up…

 

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  1. #1 by Keith Neufeld on 2012-09-04 - 16:58

    I’m the proud second owner of an Altair 8800 that literally hasn’t been powered on since 1976. I have a fair bit of work ahead of me to CAREFULLY check capacitors, voltage regulation, etc. before applying power.

    I also understand (haven’t opened it yet) that the card-edge contacts are not gold-plated and that oxidation tends to be a problem with them. My inclination would be reseat the cards a few times before applying power, hoping the wiping action of insertion would deoxidize a conductin path on each; and possibly clean the card edges with a (non-metallic, non-abrasive-impregnated) plastic scrubby pad; but I’m not sure what to do about the sockets. You seem to know what you’re doing with DeOxit, and I’m interested whether you have any particular advice for this situation, regarding sequence of events, method of application, etc.

    I just searched for your most recent post that included DeOxit. By all means take this conversation offline or move it to a different forum/medium, if you find that more appropriate. I would also be quite happy to send you photos of the cards when I get to the cleaning stage, if you’d like to post them as an example of a deoxidizing process, and if you weren’t concerned that it would draw a flood of other requests for assistance.

    • #2 by Ed on 2012-09-04 - 19:28

      the card-edge contacts are not gold-plated

      Eeeewwww! That means they’re lead-solder-coated at best and tin-plated at worst. Whiskers ahoy!

      DeoxIT Red (which is what I have a lifetime supply of) is supposed to work wonders on plain copper contacts and not much else. However, I’ve used it to good effect on pretty nearly anything with sliding contacts, so I think there’s a bit of cleaning and lubricating going on, no matter what they say.

      As part of checking the caps for ESR, you’re going to take the whole thing apart anyway, so you may as well clean the card edge contacts before reinserting them. I doubt the scrubby thing would achieve much, unless the contacts are really corroded, and it might tend to scrub off what’s left of the plating. I’d rub the contacts with cotton cloth (or lint-free pads if you’re fussy) and a dot of DeoxIT, refreshing the cloth as needed.

      The contacts inside the sockets probably have the same troubles. I’d wrap a fold of cloth+DeoxIT around some stiff cardboard and use that to wipe the contacts, so as to clean & lube them, refreshing the cloth as needed.

      Those connectors had an insertion lifetime of maybe a few dozen cycles, so I wouldn’t go crazy with the cards, lest that entirely wipe away the contacts. The Deoxit should lube the process, but I’d still avoid too many insertions…

      But that thing will be really neat when it lights up again!

      I wish I had my old Digital Group Z80 system with the dual cassette tape drives… [sigh]

      • #3 by Keith Neufeld on 2012-09-04 - 19:39

        What am I looking for by way of whiskers? Visible growth between tin-plated anything and everything?

        I have a spray can of DeoxIT contact cleaner wash. Would this be satisfactory, or should I look for some red? And am I looking for the white cotton rag to pick up crud, and when it stops, I’m done?

        I’ll take it easy on the contacts, as you suggest. Thanks!

        • #4 by Ed on 2012-09-04 - 20:05

          What am I looking for by way of whiskers?

          Anything that looks like metallic fur. That growth was a nasty case, but should give you the idea.

          If there’s outright corrosion due to moisture or somebody dumping a soda inside, then that’s a whole ‘nother problem!

          a spray can of DeoxIT contact cleaner wash

          Haven’t used that stuff, but it will probably work as well as anything. I doubt you can restore the contacts, but if they’re in OK shape (due to lack of use, if nothing else) they should work fine with a little cleaning & lube.

          I’d spritz the cleaner onto a cloth and use that, rather than hosing down the contacts & socket, but that’s just because I don’t like aerosol products. You should use it “according to package directions”, of course … [grin]

  2. #5 by hexley ball on 2012-09-05 - 13:33

    I logged quite a few miles on S-100 bus systems. Here are some things that may help get the system running:

    1. Don’t be timid when you clean the contacts of the edge connector. A few swipes with a Pink Pearl will show them who’s boss.

    2. Many of the PC cards of that era used sockets for the chips (had to, the chips failed way too often to solder them in). Unfortunately, this was before the advent of dual wipe sockets, so often the sockets themselves prove erratic. I suggest loosening every socketed chip and re-seating it to break up any oxide that has formed.

    3. The bulk supplies in the original Altair were a bit marginal. If you have the machine loaded with a lot of cards, be sure to check the +8, +18, and -18 rails to make sure they are holding up. It was not unknown to retrofit a larger transformer into the Altair for extreme cases.

    4. When it is finally running, try entering the following with the front panel switches starting at address 0:
    1100 0011
    0000 0000
    0000 0000

    That is “jmp 0000″, so you should get a nice infinite loop to light the LEDs.

    Good luck.

    • #6 by Ed on 2012-09-05 - 15:17

      A few swipes with a Pink Pearl

      You barbarian, you! [grin]

      Although an eraser shines ‘em right up, I think it embeds little rubber shreds in the nooks & crannies that tend to work out later and cause intermittents. I’m willing to be proved wrong on that, but contact cleaner would be a less aggressive way to begin negotiations.

      loosening every socketed chip and re-seating it

      Pushing firmly on the chip produces a disturbing crunch as the pins break loose and slide down into the socket; it’s hard to not wince when that happens, though.

      I worked on a project once where the CPU wriggled its way entirely out of its pin-grid-array socket and fell down on the backplane. Powered the box up one morning and only the fans started…