I think I broke my Pluto HELP!!

  • Hi All

    I went to do the TXCO mod using a board I got from DL that I seen here, I also did the GND mod at the same time,

    I had to use a huge amount of heat to remove the old TXCO but it came off eventually,

    I installed the new add on board and did the GND mod, when I reconnected the Pluto I get what looks like a slightly different USB pop up on my PC, Says Linux File stor gadget USB connected,

    I have the Pluto external drive in file manager, I have all the devices in the device manager com port ect,

    I can SSH into it and do the frequency expansion and cpu mod,

    I can ping it, doing the IIO_INFO commands returns slightly different text than what it listed but it communicated,

    but when I try to connect with either SDR Console or SDR Angle it says device not found ??

    Have I fried it tacking out the TXCO

    Is there anything I can do,

    and failing that is there anyone that sell pre-modded Pluto's ready to go,




  • So doing some more looking at this looks like C123 is missing, C124 is also missing but looking at pictures on the net this seems to be always missing,

    these small caps are spec of dust small so no idea where it went and there is no way I will be able to replace it,

    Would C123 missing cause the RF side of the Pluto to not work (RX/TX) it is on the feed from the TXCO into the AD9363 ??

    can I solder in a larger cap across some point to do the same job??




  • I was just writing that it looks like you have no TCXO signal and to check for missing C123....

    Yes, C123 is on the TCXO signal path. If missing Pluto will not work.

    I don't think is a good idea to use a larger cap...I don't know how you made the tcxo mod, may be easier to place an equivalent SMD capacitor on the output of the tcxo board and join it to the missing C123 pad...

  • Trevor,

    C123 and C124 form a capacitive voltage divider to adapt the ~1.8Vpp output level of the original Pluto oscillator to the 1.3Vpp required by the AD9363.

    The XTALN input of the AD9363 has an input resistance of about 10kOhm in parallel with 10pF, so that the capacitance of the input pin is sufficient to form the voltage divider with C123. Therefore C124 is not placed on the PCB.

    73 Jean

  • Hi Trevor, as Wilhelm said,

    please measure (scope) the signal behind the C123. C124 is not required in that layout.
    I use a GPSDO with 3.3V signal and had a 3dBm attenuator in the path to ensure 1,8V at the chip input.

    But in the first step I would remove the ground mod. As the Pluto act 'normally' (SW side) even when the TXCO or GPSDO signal is missing (just no signal receive). If my GPSDO is off the SDR console work like normal (sure without any RX signal...). So without TXCO I would expect the same... for me I would start with the USB/SW analysis.
    And two change at the same time could cause several issues. Good luck!!

    73, Oliver

  • Thanks for the replies, I do not have advanced equipment here to do much testing, and even though I am only 40 years old these components are almost not visible for me to see never mind try to work on,

    I have the unit working with a 3.3nf Cap as it's the only one I have available in my shack, I have ordered some 18pf and will try to install one of them in line,

    I no longer feel this unit is safe so I have ordered another with the TXCO mod already completed to use as my main unit in my QO-100 station,

    On another note I was told that the GND mod can easily damage the pluto due to excessive current draw, has there been many reports of this??




  • EI2GLB Trevor the only thing I know is that you should only run the Pluto with one power source. So wenn you connect the Pluto with an ethernet adapter you need a extra power supply. If you are using the Pluto with usb connection do not use an additional power supply, because the voltage comes over the usb cable. Thats all I know.

  • They are not visible to anyone. You need to work with it under a magnifier. The gain in dexterity with the feedback from the magnification is remarkable. So you can do it. You just need to practice on something less costly first.

  • Hi Trevor

    Although this might have no relation with your Pluto, I will share my experience, just in case.

    After I did the GND mod to my Pluto, the computer no longer recognized it. Better said, the computer did recognize the USB device (for second or so), but then the disconnected, then connected again... I couldn't understand out what was going on.

    I searched the foruns, including this one, and I couldn't see anything similar. I decided to disconned the external antenna (Comet GP-3 V/UHF vertical) and, for my surprise it worked fine. I connected the external antenna again, just to be sure, and again the Pluto stop working! So I have no doubt, the antenna has caused the USB crashes!

    I have no explanation for this, but I am preety sure some clever guy will know what is going on.

    On another note, the suggested 1.8V_CLK point (to supply the new TCXO), close to C170, is dead on my unit. I used a point close to C150 instead and works fine.

    Good luck

    73 FCosta, CT1EAT/M0HOJ

  • Thanks FCosta I am lead to believe that the GND mod can cause issues, I will try without it and see how I go,

    All my parts are on route from Eastern Europe so I am at the mercy of the post, There is some great suppliers over there and as a community we are lucky to have them supply us with exciting parts to further our hobby,




  • As last solution, if you stuck, I can offer my help.

    Distance is a problem but if you send it, I can try my best.

    Received in the past 6 "dead" plutos and only 2 were really dead, the other 4 are working again. 1 with a squirrly signal but it works :) If it is really dead, I can send you a complete "new" moddified one if you want. TCXO, GND, PTT , whatever you need.

    Write me an eamil and give me some days, I do not check every day my mails.

    Hope I can help