Kuka KRC1 PC not booting

    The pc psu is not receiving power from the power module in pm6-600

    Hello, I am a beginner when it comes to industrial robots. I live in Netherlands and am working on a Kuka KR15/2 with a KRC1 cabinet, I got it working the second week after it arrived but now I am having a problem:

    A week ago the Kcp showed a screen with a message it was turning off, I haven't been able to see any other error message.. Afterwards the screen was black and haven’t been able to boot the pc up since.

    First off I tried switching the 3V motherboard battery but this was not the problem.

    Then I believed it was due to the Lead acid batteries not being charged up so I left the controller on for 20 hours. Is this correct? How do I know the batteries are charging on krc1, is there a special mode for this?

    Battery reads 24.9V, but when cabinet is turned on it stays Exactly the same, hence I don’t think its drawing any current.

    Also I tested each battery under load and the voltage stayed steady on 10.3 V.

    All the fuses on the PM6 module are ok.

    The PM6 module is receiving 400V AC, it should supply 24V to the Pc psu but it not supplying any(barely, only 0.4).

    Any tips and suggestions would be very appreciated.

    Thanks in advance,

    Rik

    Edited 2 times, last by Rikkoman (December 30, 2023 at 4:19 PM).

  • Fubini December 30, 2023 at 4:52 PM

    Approved the thread.

    that is too low for lead batteries. they should not be discharged below 11.6V to prevent damage. once they are below 11V, damage is irreversible. controller may ignore batteries below some threshold voltage. this is on purpose to prevent damage for example when there is a short or if batteries are not connected correctly (one or both have wrong polarity).

    1) read pinned topic: READ FIRST...

    2) if you have an issue with robot, post question in the correct forum section... do NOT contact me directly

    3) read 1 and 2

    Oh really, great. I did however pull high current of 30A+ on my battery test and it dropped immediately to 10.8(correction, I misread) . To my understanding with a higher load the voltage should just continue to descend more over time, not immediately? I'll do another test with smaller load also.

    Thanks I'll order some new batteries and test it out.

    then battery seem to be ok. and i would not draw 30A from it. that is several times higher than rated capacity in Ah. load test can be done with 1-2A. no reason to go higher.

    so the next check is the PM600 since that is where the KPC power is from. you can try disconnecting any 24V loads (including KPC) to see if the 24VDC (actually 27VDC) does appear. maybe there is something causing overload and it could be fault in KPC or elsewhere.

    to see if KPC itself is functional, you could also bring 24V from a different source - just make sure to watch polarity.

    1) read pinned topic: READ FIRST...

    2) if you have an issue with robot, post question in the correct forum section... do NOT contact me directly

    3) read 1 and 2

    Thanks for the response, I've haven't had the chance to work on it until now.

    I tried the new battery's, of course this had no effect(old one are ok)

    Removing the kcp and then switching on had no effect visible for me(still no power to pc).

    The same with disconnecting all the other cabinet connectors(X11, X20, X19).

    I measured 400v on the X101 coming into the PM6.

    Measured nothing on the X103.

    I measured no outgoing 27v on the x202, which connects to the PC and FE201.

    I tried to bring external 24v to the PC, the PC fan doesn't turn on when I short the reset pins or the power pins on the motherboard(should be able to turn on pc manually this way).

    Perhaps I should look more into the pm6 itself

    I found a site dedicated to the PM6-600.

    Kuka KRC1 PM6-600 Repair

    And the PDF containing information and diagrams I have translated to English and put into this git:

    GitHub - Rikkopanda/KUKA: Debugging kuka robot krc1
    Debugging kuka robot krc1. Contribute to Rikkopanda/KUKA development by creating an account on GitHub.
    github.com

    It also contains a picture of one diagram that came with my machine(I cannot seem to upload png or other files to this site).

    sounds like you have multiple problems there:

    the 27.1VDC supply in PM600 is out or the fuses are blown

    the PC is not working

    if i recall, KRC1 had Soyo motherboard and AT PSU.

    bringing 24V to X961 should allow starting KPC. the CMOS settings may be lost so it may not start up immediately but shorting power-on pins on motherboard should start it

    that is if you are shorting correct pins (the power-on button pins, not the power-on LED pins)

    if this was done correctly and still not starting, check voltages on P8/P9 connectors :

    https://allpinouts.org/pinouts/connectors/power_supply/at-motherboard-power/

    and take a good look at capacitors for signs of leakage or bulging.

    1) read pinned topic: READ FIRST...

    2) if you have an issue with robot, post question in the correct forum section... do NOT contact me directly

    3) read 1 and 2

    I tried bringing 24v to the Fe201 power pin also, together with 24v to the pc. this allowed kcp to be started.

    In the logviewer we saw previous error messages, however they all seem to have the exact same date from a year ago. First messages in the log were COMMON DRIVES ERROR1 and Under voltage PM1, but not sure how to interpret it because the dates are weird.


    The fuses are not blown. I took out the pm6, also the fuse on the pm6-600 psu module is not blown and no leaking/bulging capacitors.

    I believe it has to do with de pm6-850(power source).

    Perhaps I should test components individually now, is there any advice on where to start/ technical drawings? I've seen other forums talk about a damaged voltage regulator.

    Also in the technical drawing on the psu. I saw after the rectifier a so called 'control loop'(diagram PM6_Diagram01 in the git repository), I am not sure what this exactly does.

    Or I should just find and buy a new pm6-600 module to swap out and see if it works(they are scarce).

    Ok update it works now;

    Bought 2 pm6-600's for cheap at a auction.

    Swapping out the original with either of these seems to solve the low voltage psu problem.

    System starts up, low voltage supply works, all leds are on.

    But when starting jogging there came a lot of new/unexpected problems, which wasn't present in the original.

    With the new module, lets call it B.

    I/O configuration error driver PROFISL

    A message of overcurrent on Axis 3

    smoke came out of the motor(one of the connectors on it) along with a overtemperature message on Axis 4.

    With other new module A there were similar problems but no smoke or overtemperature.

    But very wierdly when I started moving A2, all of a sudden A4 and A5 jolted very quickly for a short moment.

    KUKA/VIDEO.md at main · Rikkopanda/KUKA
    Debugging kuka robot krc1. Contribute to Rikkopanda/KUKA development by creating an account on GitHub.
    github.com

    I measured the wiring resistance of the phases in the motor cable(on motor side and cabinet side), theses measurements did differ for some axes. Most were 0.004Ohm and some had no continuity, one had 142Ohm.

    Then I swapped out just the low voltage psu of the original with a new one. Using the original module again it started up and I could jog without errors/warnings, great :beaming_face_with_smiling_eyes: !

    I did the wire resistance measurements again and it was the same as the faulty modules, so I don't think it has to do with a faulty connection.

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