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Fixed My DRO! whoo hooo!

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  • Fixed My DRO! whoo hooo!

    Woke up - started comparison testing and was still hung up on why the yellow to ground wires were such a different reading from my functioning Y and non-functioning X so started tracking things down and this time did not get sidetracked by that 3 pin transistor in the bottom right corner where the yellow wire leads too (see the little path?)

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    So --- ended up finding right where the discrepancy was --- note the little pin hole from the first pic were the yellow wire leads to - then flip the board over in this second pic and it goes to that one second from the top resistor - see the crooked butchered up replacement I soldered in ? the X and the Y "161" resistors in this place read totally different -- the Y had something like 180.something and the X had 12. something --- this was with my meter on "auto" mode so have no idea what it means just that it's way different and was causing the difference in readings right from the leads,,, so closest I could find was a "151" in my scrap computer boards and stuff and it was a little more compact as you can see - it read around 160. something in the auto mode and that was before and after I soldered it in, fired up the DRO and the X took right off and has not skipped a beat since - that's running it full range at probably 10 times the speed I could ever crank the handles ----------- this is the best it's ever done since the glitch appeared a few years back -------- I ran both the X and Y lock to lock back and forth 15 times each and neither skipped a beat!!!

    very excited...

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    Here's the pic of the culprit that drove me mad, and I still have no idea why the Y would glitch once in awhile either - but it's been solid for days now so will cross that bridge when I come to it --- unless the bad resistor in this scale could have been robbing more power and creating a mess to the whole system - have no idea just glad to have things functioning normal for the time being,,,

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    Im going to mount it all back in the mill - and play around with it today - if it's good all day then im heading out to get me a steak and a high quality 6 pack of IPA's....

    thanks all for you help in answering my dozens of questions... I learned allot from you guys along the way...

  • #2
    AK, how did you solder that bad boy in without overheating the component or bridging ? (excellent save on the DRO)


    • #3
      I just used my crude 30 watt single point iron,,, I removed it from the scrap computer board and tested it and it was still ok and read the same - I then held it down on the other board with the tip of a regular screw driver in it's middle area (heat sink?) and just blipped the ends real quick and then tested again and it held,

      I have to mention then tested the leads at the DRO readout cable ends to compare and they are very close to the same readings now for both Y and X and that was not the case before I did this - way different...

      Just now went back and tested the old one (after removing it from the penny of course lol)

      it tested close to what it was on the board --- 11.38 and it was 12. something on the board where as the Y's 161 is 180. something and the current replacement on the X is a 151 and reads 160. something --- so guess I had a rare bad resistor? I know these things are pretty dependable but this one has something wrong with it...
      Last edited by A.K. Boomer; 03-07-2021, 02:54 PM.


      • #4
        Surface mount resistors fail sometimes as a result of mechanical stress or soldering stress. End ”plates” separate from the resistice track resulting in intermitted connection.

        exellent job considering that you were using auto mode on dmm and measuring ”some units”
        Location: Helsinki, Finland, Europe


        • #5
          Glad to hear you got a good result, I doubt if I could have managed it.


          • #6
            nice! Might be worth adding a bit of solder to that middle wire too, looks like it's only soldered on the front side of the board and not at the back.


            • #7
              Impressive fix!
              Location: Saskatoon, Saskatchewan, Canada


              • #8
                Originally posted by old mart View Post
                Glad to hear you got a good result, I doubt if I could have managed it.
                Same here, that would have been the bin and a new one bought a long time ago.


                • #9
                  Originally posted by oxford View Post

                  Same here, that would have been the bin and a new one bought a long time ago.
                  You don't know how close I came to posting pics of the display unit with arrows half way through it,,, Im glad I stuck it out! I just got done mounting everything up and adjusting, then fired it up --- found a precision collar to mount in my three jaw that was already on the RT, stabbed it with the blunt end of an endmill ---- zeroed the scales then pulled out and went totally frantic with all kinds of spastic moving of both X and Y at the same time, reverse to foreword shots all throughout the ranges --- hundreds of little jerky motions and then the moment of truth --- just watching the scales I went back to zero on both the X and the Y - is the endmill going to stab without interfering ?

                  Yes totally clean, did the process again - again totally clean --- im VERY happy - heading out to get my steak (found NY strip on sale) and some beer...


                  • #10
                    For future reference, SMT (Surface Mount Technology) resistors are marked such that the last digit is the number of zeroes to add after the first two (or three) numbers, and the result is resistance in ohms. So the 151 is a 150 ohm resistor. Standard values for 10% tolerance would be like 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, and 82, and multiples of ten thereof. 5% resistors include values between those. or 11, 13, 16, 20, 24, 30, 36, 43, 51, 62, 75, and 91. Capacitors and inductors have similar values. Some, mostly older axial carbon resistors, use a color code.

                    Most SMT resistors are metal film, and they are quite tolerant of high temperatures encountered in soldering and removal. Even ceramic capacitors, silicon transistors, diodes, and ICs can tolerate soldering temperatures of 300-400o C for 5 seconds or more. It is unusual to find a defective or damaged SMT component, but it happens.

                    Once you remove an SMT component from a PCB, dab a little non-corrosive flux on the pads, and remove excess solder. Then position the replacement component on the pads, apply solder to the joints, and then follow procedure to clean off the flux (alcohol), followed by scrub with detergent, clean water, and dry thoroughly using a heat gun or oven.

                    I hope your repair proves to be successful. Time william tell...
                    Paul , P S Technology, Inc. and MrTibbs
                    USA Maryland 21030


                    • #11
                      Paul your a Wizz --- and I knew something had to do with the last numbers being critical because even when I found a complete number that was even closer to the over all 161 number it did not measure correctly in fact some way off --- so I just started comparing ones that were maybe not quite as close overall but close when I measured them, and the 151's were the closest I could get...


                      • #12
                        The really good flux, if you do much of this, is a flux pen from Digikey. It is some sort of lemon-oil based stuff, that you'd think, "yeah, right" about, but it works super.

                        You can even solder a fine pitch SMT processor easily by fluxing the pads and leads, cleaning the iron tip, getting some solder on it, then going along the pins. Each takes what it needs, no blobbing, and it just works without hassle.

                        Resistors etc are a snap.

                        You did a good job of it on the DRO, and it is probably a positive "fix". Smart work!
                        CNC machines only go through the motions.

                        Ideas expressed may be mine, or from anyone else in the universe.
                        Not responsible for clerical errors. Or those made by lay people either.
                        Number formats and units may be chosen at random depending on what day it is.
                        I reserve the right to use a number system with any integer base without prior notice.
                        Generalizations are understood to be "often" true, but not true in every case.


                        • #13
                          And, you have beaten half-nuts Mattthemuppet for finally solving the painfully frustrating long-running puzzler of the month!
                          "A machinist's (WHAP!) best friend (WHAP! WHAP!) is his hammer. (WHAP!)" - Fred Tanner, foreman, Lunenburg Foundry and Engineering machine shop, circa 1979


                          • #14
                            Thanks all - probably made less than 5 bucks an hour on it when you consider how much time I got in it and what a new one would have cost, but im cheap, and determined, and it's allot of good quality components that would have hit the scrapper for what? look at the size of that little thing, how much one cost?

                            but not cocky - as Paul stated - time will william tell,

                            but for now - two pics are worth a thousand words... OMG was it good. just noticed now there was most likely a dog hair on my beer - don't even care if it went down the hatch - that good... ( I think it was on the safe side)

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                            • #15
                              Originally posted by mickeyf View Post
                              And, you have beaten half-nuts Mattthemuppet for finally solving the painfully frustrating long-running puzzler of the month!
                              Lol to cap it off --- im going to listen to Tom Petty's "won't back down" followed by "it's good to be king" then maybe Jimmy's "hey Joe" just to keep things real lol

                              if tomorrow when I wake and fire it up and the glitch is somehow back you will be getting some pics in the morning of the arrows penetrating the aluminum casings --- on everything....