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What is wrong in this power supply circuit? Pictures

Discussion in 'Troubleshooting and Repair' started by Stevenl, Jan 18, 2015.

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  1. Stevenl

    Stevenl

    3
    0
    Jan 18, 2015
    Hey,

    i have a problem with a Fanuc power supply that was powered with 400v instead of 200v AC.
    Fanuc part nr is A16B–1211–0850.

    the problem is that one of the channels is giving a to low voltage while the others are giving to high voltage. Could anyone give me some tips to where the problem could be here? Which components should i check first? None of the fuses are or have blown. See pictures, the first picture is the measured voltages on each channel. The second is the whole power supply circuit who is feed with 200v AC.

    strømforsyning engelsk.jpg strømforsyning2.jpg
     
    Last edited: Jan 18, 2015
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    9,632
    2,013
    Nov 17, 2011
    Welcome to electronicspoint.

    Your measurements are not plausible. When you measure 1.2 volts on the +24V rail, how should RG12 be able to generated 28.5V on the +15V rail? Only if F13 has blown, but you state that the fuses are all o.k.

    Check also the voltage on A15 and the control signals to transistors Q14 and Q15. Is the reference voltage A5 o.k.?
     
  3. Stevenl

    Stevenl

    3
    0
    Jan 18, 2015
    Thank you for your answer :)

    My measurments are what they are, haha.

    The fuses f11, f12, f13 and f14 is ok.

    What should i read at A15?

    It says in the manual that the reference point A10 should read 10v. This is adjustable with VR11.

    Here is the service manual, power supply from page 114 : http://www.automationservice.biz/file/userfiles/file/MAINTENANCE.PDF

    I cant check anything more before wednesday because im at work until then.
    But i will add a picture of the unit, the best i could find online.
     

    Attached Files:

  4. Harald Kapp

    Harald Kapp Moderator Moderator

    9,632
    2,013
    Nov 17, 2011
    The 28.5V on the +15V line can't come from RG12 as this sees only 1.2V at the input. Therefore the 28.5V come from somewhere else in the unit and are returned to the power supply on the 15V line.
    The only way I see is via the +24V line where you actually measure 45.7V.

    What about diode DS17? Is it o.k? I'd guess not. It is the only component that prevents the 45.7V on the +24E line to appear on the +24V line too. Since it doesn't look like the 24V being regulated, it may suffice to put the normal load onto +24V to bring the voltages back into the normal range.

    About A15: I'd expect it to be 15V.
     
  5. Stevenl

    Stevenl

    3
    0
    Jan 18, 2015
    Update!

    Have now measured and checked around a bit again.

    It appears that the 24V regulation works fine when it is put on load.
    The power supply has two connectors supplying two different devices with power. And when i disconnect the power supply from the motherboard and let the small connector with 24V stay connected, both 24v outputs look good! The 24V part connected is going to the CRT screen in front. This now work fine. But as soon as i connect the big blue connector to the motherboard it starts acting up.

    So then it suggests that the fault lies in the second regulation loop with 15V, -15V and 5V? Most probably the -15V since that one is much higher?

    D35 and C63 is good.

    All measurements below is with the connector CP11 and CP15 connected only.

    power supply.png 20150121_182003.jpg 20150121_182034.jpg 20150121_182116.jpg 20150121_182137.jpg 20150121_182149.jpg 20150123_075733.jpg 20150123_075738.jpg 20150123_075749.jpg 20150123_075801.jpg
     
  6. abadade

    abadade

    4
    0
    Nov 21, 2019
    Hello
    I have also a problem with this Power UNIT without load all voltage its ok once I connect the power unity to mother board 5VDC go to 1V and also -15VDC when I power supply with external power no short-circuit and the current its 2.5A so do you have any idea ?
     
  7. WHONOES

    WHONOES

    774
    168
    May 20, 2017
    Most switch mode power supplies require a load on at least one of the outputs to be able to regulate properly. In your instance, it seems to be the 5V output, which is quite common. Having had a quick squint at you schematic, I spotted "Dummy Load R56" that serves just that purpose. I suggest you check it to see if it is O/C as it could be part of your problem.
     
  8. abadade

    abadade

    4
    0
    Nov 21, 2019
    thank you The resistor its OK 20Ohm
     
  9. abadade

    abadade

    4
    0
    Nov 21, 2019
    The resistor R50 in my Board its OK 20Ohm.I have also R11 not energized and I don't know why ?
     
  10. WHONOES

    WHONOES

    774
    168
    May 20, 2017
    The 2nd schematic is very difficult to read and I cannot see an R11.
     
  11. abadade

    abadade

    4
    0
    Nov 21, 2019
    Hello
    Its RY11 a relay so without Datasheet I can't define if the problem its M13 or M14
     
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