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  • DRO electronics question...

    Im still not giving up on the DRO, yesterday I was testing individual resistors and came across one that varied immensely from other duplicates on the same board - I removed it to make sure and it then behaved normal so something else in the circuitry was giving me the crazy readings,

    Anyhoo, so today im back on the sunporch plugging away checking stuff out - when I run across the only crystal oscillator on the entire board and check the two leads, nothing - nothing in either direction and that's with all settings on the ohms and also in "auto mode" yet - yet ,,, one of the leads has some continuity if you check it to it's case,,,

    So I did not even know what to call the bastard and went and looked up component identification so as not to bug you guys any more than I need too, hence the fancy name I came up with of C.O. ,,, anyhoo, so I got out all my other computer crap and found about 5 littler C.O.'s and checked them, ALL the little bastards have some continuity between their two leads and NONE of them between any of their leads and their casing -------------------- am I onto something ?

    first pic is of my larger DRO's C.O. and second pic is of one of the smaller bastards on another non-related board...

    LMK what you guys think, could this be jacking stuff up? if it's bad can i by-pass the clumsy bastard ?




    Click image for larger version  Name:	DSC05511.jpg Views:	0 Size:	51.7 KB ID:	1929247 Click image for larger version  Name:	DSC05512.jpg Views:	0 Size:	48.5 KB ID:	1929248 thanks

  • #2
    No... you're not on to something. If ANY of the XTALs (crystals) were bad, you wouldn't be seeing any numbers change on the display.

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    • #3
      A crystal is essentially a piece of insulation. For one wire to be connected to the case is for the sake of shielding- otherwise it isn't part of the properties of the crystal. If there's a resistance between the leads it should be very high. There are different materials used in crystals, so I can't say whether you should be able to measure any resistance at all. A quartz crystal for example should be an open circuit.

      Some measuring instruments might react to the crystal and give false readings- after all the crystal is meant to oscillate and could be reacting to the instrument. If you vibrate the crystal mechanically it will generate a voltage and not behave strictly like a capacitor or a resistor- but that voltage could confuse a meter. I'm not saying it will, but it could-
      I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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      • #4
        Thanks Darryl - good info - You too SLK, if it's not going to help fix it then im done for the day...

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        • #5
          Think of it as an electronic tuning fork- if you 'bump' it with an untuned frequency that's close to its natural resonance, it then resonates at its exact
          tuning frequency. Kinda cool- and utterly essential. The case should be isolated from the crystal itself, so that's right. They also never fail...

          t

          rusting in Seattle

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          • #6
            Well why is it essential then? and if it's essential what does it help or hurt? BTW, neither of the leads end up having continuity to the case --- I found out the case sits on a huge base of solder almost the size of the case itself and when I was testing with a probe on the case it pushed the case into the solder base and that's actually connected to something that's obviously connected to one of the lead connections, thats where I was getting fooled with that... thanks

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            • #7
              Their using it for something right? is it a certain frequency that cockroaches hate and it keeps them from invading the unit? gotta be a reason...

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              • #8
                Originally posted by A.K. Boomer View Post
                Well why is it essential then?
                They are the system clocks. Since computers run one instruction right after another, the clocks simply set the rate of those instruction steps. Without them, you have a boat anchor.

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                • #9
                  Originally posted by SLK001 View Post

                  They are the system clocks. Since computers run one instruction right after another, the clocks simply set the rate of those instruction steps. Without them, you have a boat anchor.
                  That's incredible SLK -- what a crazy world you guys live in lol so kinda like a rate establish'er of sorts? probably runs at close to the expected capacity of all the "thinking" components and what their designed for???

                  could it hurt to try another of a different frequency ? I mean as for as blowing something up???

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                  • #10
                    you want to overclock your dro?

                    Damn gamers!
                    Last edited by lakeside53; 02-19-2021, 07:43 PM.

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                    • #11
                      Originally posted by lakeside53 View Post
                      you want to overclock your dro?

                      Damn gamers!
                      ROFL!
                      There are no stupid questions. But there are lots of stupid answers. This is the internet.

                      Location: SF Bay Area

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                      • #12
                        Hey people hop up their alarm clocks fer cry sakes --- im sure it's not the first time someone tried to hop up a DRO...

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                        • #13
                          The 11 Mhz. crystal is quite common in electronics...........

                          11.0592 MHz Crystal Oscillator
                          generate UART clock (8×1.8432 MHz); allows integer division to common baud rates; common clock for small microcontrollers.

                          You won't get any reading / continuity across the terminals. Some resistance from one terminal to the case is normal. Those crystals are available at any electronics catalog co. Mouser has them.

                          As far as the resistor being bad, I doubt it. If you not sure about it it would be best to remove one lead from the board to get an accurate reading.

                          JL..............

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                          • #14
                            As I said in the previous thread, your problems are NOT in your main electronics box. Most likely they are in a cable, a connector or your scales.

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                            • #15
                              Originally posted by SLK001 View Post
                              As I said in the previous thread, your problems are NOT in your main electronics box. Most likely they are in a cable, a connector or your scales.
                              Y'know, I'm not so sure about that. AK has said that in several instances the problem switched from one axis to another, not rolling predictably as he moved connectors. And, as I recall, sometimes switched axes after shutdown overnight. Yeah, AK isn't knowledgeable about electronics, but I know he's a good troubleshooter. Just read his posts on weird mechanical problems.

                              SO: I suggest there's some common problem. First thought was erratic power supply - erratic voltage occasionally, noise in the supposedly clean DC, a curse from an ancestor violating an Egyptian tomb, that sort of thing.

                              Or maybe, simply wonky grounding of the signals allowing nearby interfering sources of crap to confuse the DRO.

                              AK can't identify these issues because he doesn't have a scope. Or, apparently, a good DMM.

                              First thing he might do is run some independent grounds between the sensors and the head...

                              -js
                              There are no stupid questions. But there are lots of stupid answers. This is the internet.

                              Location: SF Bay Area

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