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Mill --- Let thy be healed (bigger than Jesus)

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  • Mill --- Let thy be healed (bigger than Jesus)

    Well not by much - but according to records I think I got about 15 lbs on him,,,

    Anyways ---- years ago I think I might have been given some bad advise on here about my DRO, it started to flake out when I first turned it on, would flicker and the numbers display would only be like half connected and hard to read, then once warm it worked fine, I tore into it and seen some puffed out caps so gutted out an old computer for same value stuff, threw them in and problem totally solved and I was so happy I posted about my fix,,,

    someone ended up chiming in and said to just start leaving my DRO on all the time as its the cool down and warm up's that are rough on things, and it takes next to nothing to leave on (electrical costs) im not an electronics guy but this did kinda make sense to me so I started leaving it on for days at the time - then weeks - then months,,,

    then my glitch showed up in the X scale --- well I never fixed it but started to shut down the unit off when not using sometimes for weeks and low and behold it's been rock steady - I had not had a glitch in about 4 months or more in fact it really does coincide with shutting the unit off and giving it a break,,, does this make sense to anyone electronic wise? it is for sure in the scale and no caps or anything in there that I know of --- what component in a scale could benefit from this?

  • #2
    We used to cycle electronics using cold sprays and heat guns to show up intermittents that would otherwise escape detection. Consider that differing materials have different expansion coefficients, and it's a wonder that electronics can survive at all. Sometimes a deep cooling will fix a problem for some time, other times a resoldering can put enough heat into a junction to cure an ill- even if the point being resoldered wasn't the problem in the first place.

    Considering the very small dimensions inside an IC, it would seem that getting a life-long connection between components and lead outs would be a daunting task to begin with, and with all the heating and cooling during use and off times, the chances of an intermittent would be high.

    Removing and applying a voltage can be enough of a shock to affect a borderline connection or trace- or component. Electrolytic caps don't particularly like operating at zero voltage- they have a tendency to go open. And when operated at rated voltages, they can be quite stressed- particularly in a switching power supply circuit. Couple this with an inferior electrolyte or inferior separator and/or metallization and it's a wonder that some of these caps last as long as they do. Other types of caps may develop problems when a voltage is across them- many of these tiny caps use materials that are quite voltage sensitive. Leaving them sit at zero voltage can 'heal' them.

    I'd like to hear the 'definitive word' on leaving it on or powering off between uses. It has been said that leaving your computer on is best- others like myself have been turning it off between usage for decades with no tangible evidence that it hurts anything. The same 'advice' can go for all electronics- do you leave your stereo on 24/7? Do you shut off your fluorescents when leaving a room, or do you leave them on-

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    • #3
      Many things can cause electrical failure. It AT&T we were taught that the major causes of failure were excessive heat, excessive voltage, static and vibration. That was before the market was flooded with cheap electrolytic capacitors. Often the introduction of any of these factors will cause other failures that introduce excessive voltage, heat, etc.

      In your case it sounds like you may have a component that is overheating and thus going out of spec. Overheating can cause opens, changed values and shorts too. When it cools it drops back to the correct value and works until it overheats again.
      At the end of the project, there is a profound difference between spare parts and extra parts.

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      • #4
        Originally posted by darryl heinrich View Post
        ....

        I'd like to hear the 'definitive word' on leaving it on or powering off between uses. It has been said that leaving your computer on is best- others like myself have been turning it off between usage for decades with no tangible evidence that it hurts anything. The same 'advice' can go for all electronics- do you leave your stereo on 24/7? Do you shut off your fluorescents when leaving a room, or do you leave them on-
        "Definitive"? Maybe not.

        But the turn-on event is stressful on the power supply. Capacitors get a surge of high current, rectifiers ditto. Regulators warm up and expansions due to heat occur. I have seen cases of power transistors having the leads crack due to thermal expansion and resulting fatigue. That was on some of the large sized Japanese audio transistors with two bolts holding them down.

        The rest of the circuit must warm up also, with some of the same issues.

        Leaving the electronics on is probably less overall stress, so long as they do not heat up too much, and so long as that means they stay at a constant temp.
        1601

        Keep eye on ball.
        Hashim Khan

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        • #5
          FWIW - it's not about the main DRO anymore - that problem has been long fixed, it's all about the X-scale, and it's verified by swapping the X and Y leads and then the glitch moved over to the Y read out,,,, and it's not about the cable leads or their wiring, I moved them all around while working the table back and forth many times,

          it was all about the X-scale's reader head, I took apart the scale and cleaned the glass and reader head, still had the glitch, I gave up except for shutting the unit down, it's been many months now and not one glitch! I have ZERO idea how the reader heads work. maybe like my garage door opener safety lights that have to be aimed at each other? don't know, but the electronics is not typical in there - there are very tiny and no caps that I can see or anything,

          Darryl's post sounds like it might have something to do with it but basement was always cold and so were the scales... I did take a heat gun to get them warm and see if their was a difference and no change...

          I have no idea but if someone does id sure be interested in hearing about it. can a component in there get it's values back by just catching a break by being turned off? if the DRO is on it means the scales are powered up --- this was not something I gave a thought too when I started leaving the system on all the time, now I don't think it's good practice...

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          • #6
            Originally posted by A.K. Boomer View Post
            FWIW - it's not about the main DRO anymore - that problem has been long fixed, it's all about the X-scale, and it's verified by swapping the X and Y leads and then the glitch moved over to the Y read out,,,, and it's not about the cable leads or their wiring, I moved them all around while working the table back and forth many times,

            it was all about the X-scale's reader head, I took apart the scale and cleaned the glass and reader head, still had the glitch, I gave up except for shutting the unit down, it's been many months now and not one glitch! I have ZERO idea how the reader heads work. maybe like my garage door opener safety lights that have to be aimed at each other? don't know, but the electronics is not typical in there - there are very tiny and no caps that I can see or anything,

            Darryl's post sounds like it might have something to do with it but basement was always cold and so were the scales... I did take a heat gun to get them warm and see if their was a difference and no change...

            I have no idea but if someone does id sure be interested in hearing about it. can a component in there get it's values back by just catching a break by being turned off? if the DRO is on it means the scales are powered up --- this was not something I gave a thought too when I started leaving the system on all the time, now I don't think it's good practice...
            Leds and phototransistors that make the read head work are somewhat temperature sensitive just like optocouplers. If the read head is already marginal the long operation might push it just off the cliff.
            Click image for larger version

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            • #7
              Originally posted by darryl heinrich View Post

              I'd like to hear the 'definitive word' on leaving it on or powering off between uses. It has been said that leaving your computer on is best- others like myself have been turning it off between usage for decades with no tangible evidence that it hurts anything. The same 'advice' can go for all electronics- do you leave your stereo on 24/7? Do you shut off your fluorescents when leaving a room, or do you leave them on-
              It really depends on failure mode. Temperature has profound effect on many failure modes so anything running excessively hot is usually better turned off when not in use. (Incandescent light bulbs, power supplies that operate warmer than lukewarm) Some components like batteries and electrolytic capacitors tend to fail in any case and best operating strategy depends on particular machine/component.

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              • #8
                Was on it most of the day today, I do leave it on for the day when using it, before - the glitch would have acted up at least a half dozen times for all I did, it was flawless, I was having to confirm it did not skip by double checking with the dials on my handle (PITA!) and now I don't even do that its been so solid - could still get bit im sure but for months it's been good so im glad I did not rush to buy a scale as they are kinda pricey... at least for now - keeping my fingers crossed and if I get into anything that I have a ton of time in or is super expensive I most likely will still be double checking the critical stuff with the dials.

                thanks for the crash course (bad choice of words) in the finer details of the electronics you guys.

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