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    #1

    Need help testing an oscillator.

    Hi,
    I have never tested an oscillator, but I think that I have one that might be faulty. It's a 20mhz one it says H20.000M2 on top of it if it matters.
    I have heard from somewhere that it is possible to test it somehow (with some resistors and a cap, I think) without an oscilloscope. I don't have a scope so this is the only way for me to test it.
    Also is there a way to bypass it somehow? By that I mean make something that acts as an oscillator or something like that.
    If anyone cares it's from a j-r programmer v2. A nand and jtag programmer.
    Any advice is welcome!
    P.S. What would happen if I put a 48.000M one in there?
    Last edited by reaper57; 01-16-2015, 03:10 PM.
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    #2
    Re: Need help testing an oscillator.

    If you make a high pass filter with a resistor and cap and then a low pass, then perhaps you can get some indication of functionality; but a scope and frequency counter is still the best way.

    This is a very crappy HPF-LPF:

    C1 IN n1 0.001uF
    R1 n1 GND 10K
    R2 n1 OUT 1K
    C2 OUT GND 0.1uF

    If you get some voltage at the OUT port when the oscillator can is on, then likely it's at least somewhat working; if it's 0V then it's dead.

    This is for oscillators, if it's a simple passive crystal, you have to amplify it.

    You probably can't really bypass it except with another oscillator of the same frequency, alterations could cause problems with the microcontroller.

    Usually oscillators don't go bad, at least I haven't had one die yet.

    Comment

      #3
      Re: Need help testing an oscillator.

      Are you trying to test the crystal by itself or the oscillator module/board?
      Do you have short wave radio that you can put close to the board and then you may be able hear changes on the radio?
      Last edited by budm; 01-16-2015, 03:37 PM.
      Never stop learning
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      http://www.badcaps.net/forum/showthr...956#post305956

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        #4
        Re: Need help testing an oscillator.

        I think he is talking about a console stuff , the j-r programmer is supposed to program a RGH chip used on xbox 360 consoles .

        Comment

          #5
          Re: Need help testing an oscillator.

          A simple crystal tester ckt:
          http://electronics-lab.com/projects/test/010/

          Comment

            #6
            Re: Need help testing an oscillator.

            If you think it is faulty it is probably simplest to replace it but you do raise a good question because I've read scoping it can shut it down anyway.

            Comment

              #7
              Re: Need help testing an oscillator.

              It looks like it uses a crystal and not an oscillator, the amplifier is in the chip on that board. So a simple hpf-lpf test wont work, you'll need to isolate it as the load produced by the test will cause the oscillator to stop working...

              They're cheap enough, agreed, just replace.

              Comment

                #8
                Re: Need help testing an oscillator.

                Unless it was dropped, the crystal is probably OK, and likely you have some other problem. I have yet to find a bad crystal aside from one in a laptop that was physically smashed.
                "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                -David VanHorn

                Comment

                  #9
                  Re: Need help testing an oscillator.

                  Without having a scope, just make an RF probe (cap and a diode) and your multimeter set to DCV. You are just looking for the presence of AC.

                  Comment

                    #10
                    Re: Need help testing an oscillator.

                    Thank you to everyone that has replied to this thread! @SM-Piyes90 that is correct! It's not only used to program the RGH chip, but it is also has an SPI that is used for r/w the nand.
                    @eccerr0r Isn't is called a crystal oscillator? The crystal or the oscillator or the crystal oscillator or however it's called wasn't soldered all the way in the hole on one side, and it did spend a few hours in my laptop's bag. But I am careful with it so I don't know if it got too much vibration from there. I ordered the replacement on Friday, but it is going to take some weeks to get here (it's from China).
                    I tried to solder a 12m one and it showed up as an unknown device straight away. I really hope that this is the problem as I have re-soldered everything (apart from the switches and plugs) on the board and tested all of the caps for shorts so if that's not the problem it's probably the IC. Team Xecutor (the manufacturer of the device) are pretty strict when it comes to their devices so I doubt that finding the IC type will be easy.
                    Anyway if anyone has any ideas on what to try tell me and I'll do it if I can.
                    I'll keep you posted on what's going on with the repair.
                    Last edited by reaper57; 01-20-2015, 04:20 PM.
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                    Comment

                      #11
                      Re: Need help testing an oscillator.

                      The crystal by itself doesn't oscillate. It needs extra circuitry to do so, the resulting circuit including the crystal is the oscillator.

                      Sometimes the crystal and oscillator circuit is built together in one can which has 4 pins. These are quite large. Some SMD crystals are also in a 4-pin package, but the 2 extra pins are just for grounding the case.
                      "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                      -David VanHorn

                      Comment

                        #12
                        Re: Need help testing an oscillator.

                        The crystals arrived a day ago and I changed the one one my programmer, now it's detected as it should be in windows and I programmed a xilinx chip with it, thank you to everyone for your time, assistance and information, I really appreciate it!
                        Keyboard not detected, press F1 to continue...

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                          #13
                          Re: Need help testing an oscillator.

                          Good to hear
                          "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                          -David VanHorn

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