HOME / KC901 serial VNA

defective 901 S ???

By DG9BFC •  2016-02-24 04:15:16 •  824 clicks
Dear friends

My superb analyzer stopped working

EXACTLY after one year (i found a print on pcb with 19.02.2015 showing as date) ...

The unit does not do anything anymore

Can not be switched on ... no beep ... no blink

Plug in charger and it does not show the charging sign on display (that round sign showing charge of battery when charger is plugged in)



Completely dead

Batteries are well charged (charged externally cause I did not know if internal charger works)

When charger is plugged in then the orange led in the unit is lit (so the fuse is ok and it is just the charger fuse)

Or is there a second fuse somewhere that I did not find yet??

Between batteries and mcu???

Is there anything I can check BEFORE sending the unit back in for repair????

Is there maybe a hidden function somewhere to reset the unit and bring it back to life?? ... maybe a bridge to be set on pcb???

I am fear to send the unit complete around the globe if maybe I can solve it here

Maybe I can test (and change) the switching regulator or a different part??

As you lknow I have built an mchf ... so I know stm32 and I also know surface mounted parts ...

So ... PLEASE help me


Your friend and betatester



ps I am glad that I did not sell my 901h yet ... otherwise I had nothing to measure with up to 3 gig

anything  charging  battery  charged  display 

9 Reply | until2018-12-13 11:35Add a reply
    DG9BFC  2017-11-17#1 -Reply


    i am only using original charger ... and that charger is working fine (also use it somtimes for powering other things with 12v dc and charger is still good)

    KinnieDhar  2016-03-20#2 -Reply

    For your spectrum analyzer i want to know that what device or signal you connected to it last time. Is your power supply working correctly?
    Also first of all check the power supply and the display section,

    cychen  2016-03-15#3 -Reply


    Hi,thank you for the positive feedback and I am glad to hear that you are enjoy using KC901S. You are welcome to leave us any feedback, opinions or questions.


    Kj4YMN  2016-03-15#4 -Reply

    I like your response cychen, very comforting to know you stand behind your product. My KC901S has been working very well and is extremely useful in the shop.

    DG9BFC  2016-03-05#5 -Reply


    is there no way to do a check BEFORE i send it injQuery110203344396760704266_1457189384778

    can i atach my stm32discovery kit (the stlink part) and reload firmware that way??

    would you please send me the mail adress where i should it send in??

    best would be if you send the exact adress via mail to dg9bfc(at)freenet.de



    cychen  2016-02-29#6 -Reply

    @DG9BFC Hi sir, we suggest you to ship back the KC901S so that we can take a check.

    DG9BFC  2016-02-24#7 -Reply

    it is about one year old (plus minus a few weeks) ... was working fine before ... suddenly stopped working (complete black)

    pressing f3 f 4 f5 and power did not work

    pressing f3 f 4 f5 and CS did not work

    unit does nothing ... no beep no blink

    DG9BFC  2016-02-24#8 -Reply

    serial number is 201552255115

    cychen  2016-02-24#9 -Reply

    Hello Sir,

    would you mind telling me the serial number of your KC901S so that we can try if we can find what cause this problem first? Thanks.

    Best regards


LoginPublish or Still no account?Register


Theme List

KC901 serial VNA

Relevant topic