APC UPS units - troubleshooting

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  • csh
    replied
    APC SMT1000I, 2011 model, recap

    Hi, I need some advice from the experts in the APC recapping department :-)
    Got an older APC SMT1000I, 2011 model without fan that I would like to save if possible.
    It came with 2 noname 7Ah batteries inside and some packing foam to fill the space, someone was creative :-)
    It's working fine, tested it with light load, it charges batteries, passes self test, no strange behaviour.
    Except for some quiet high freq hissing coming from a transformer compartment. Its hissing all the time, with or without battery, on battery...
    Starts a second or two the after connecting mains power, after some relay clicks.
    Don't know if hissing is normal for those APC units, but because of age, I would like to recap it before use.
    It has 2 PCBs, large main one covering the whole top of the case and a smaller one that looks like some kind of PSU stuck in the back corner behind the transformer.
    Right about where the hissing is coming from :-)
    Main PCB is clean, no bulged caps, but as I was able to research, some small caps always fail on the APCs.
    Small PCB is a different story, it was partially covered in some black soot in the region between the blue Y capacitor, transformer and two larger caps.
    After treatment with isopropyl and a soft brush board is squeaky clean, no burnt components, just some darker spots from the heat on the back.
    The plan is to replace all electrolytics :-)
    I'm a hobbyist, not a pro, so I apologize in advance for my lack of knowledge :-)

    My questions:
    1. I was able to find the spec sheets of all the caps except the two SMD.
    Pictures with markings and position attached.
    Those have markings:
    Code:
    19
    33
    35V
    and
    Code:
    D1
    47
    35Z
    So I'm guessing 33uF/35V and 47uF/35V, general purpose?

    2. The small PCB is bothering me, where did that black dust come from?
    Nothing visibly blown, that protection cap is not open, it tested in circuit to something like 4.3nF which sould be in spec.
    Diodes around it are not shorted. Could it be from the transformer?
    3. This big cap at position 12 (C85) is EPCOS / TDK B41848-A7278-Z.
    I'm having trouble at finding a replacement, any suggestions about that?
    4.Anybody knows what is this smaller PCB for, some charger for battery or...?
    5. Is there any way of detaching the black wire coming from battery connector in the back? It's the only one soldered directly to PCB :-)

    Main board caps
    Code:
    Position    PCB mark        Brand / series   Values
    1        C610          OST RLG       47uF 16V
    2        C60           Uknown SMD     33uF 35V???
    3        C606          Uknown SMD     47uF 35V???
    4,7,9,10,11   C75,C35,C114,C100,C115 Lelon SSG      22uF 16V
    5        C77           Lelon RGA      47uF 63V
    6        C85,C102        IC RZM (Illinois)  330uF 25V
    12       C85           EPCOS / TDK     2700uF 40V
    Small PCB caps
    Code:
    C903      JNC JN472M (had some soot on it)
    C917, C918   Jianghai CD 263 22uF 400V
    C904      IC (Illinois Capacitor) 22uF 50V
    C938      IC (Illinois Capacitor) 10uF 50V
    C906      Jamicon TK 330 uF 5
    0V
    Attached Files
    Last edited by csh; 08-19-2023, 11:49 PM.

    Leave a comment:


  • foundups
    replied
    Re: APC UPS units - troubleshooting

    Originally posted by Behemot
    told ya

    what did you do with da buzzer?
    I resoldered it on the board.

    Leave a comment:


  • Behemot
    replied
    Re: APC UPS units - troubleshooting

    told ya

    what did you do with da buzzer?

    Leave a comment:


  • foundups
    replied
    Re: APC UPS units - troubleshooting

    Hi, I was finally able to fix it!
    I replaced almost all the capacitors with new ones, and it is working again. I still need to check if the battery is being recharged.

    Leave a comment:


  • Behemot
    replied
    Re: APC UPS units - troubleshooting

    dammit looks like me response was not sent

    transformers rarely go bad and pretty much always are custom part, it's more likely some of them SMD components under it went bad, I'd say start with those diodes and resistors near the divider, around TP6 and 7?

    Leave a comment:


  • foundups
    replied
    Re: APC UPS units - troubleshooting

    Hi, thanks for your response.
    I noticed that the buzzer gets very hot, so I desoldered it.
    You're right, I found a bad 22uF cap near the buzzer.

    I measured R155 and is about 10 ohm, is a value a bit high for a shunt.
    I think the current is measured through the CT1 transformer, the model is "460-0102C-Z LEI-8 ID30" but I can't find the datasheet.
    Attached Files

    Leave a comment:


  • Behemot
    replied
    Re: APC UPS units - troubleshooting

    I've now checked that soldering side of yours, it's also baked under the buzzer so the caps nearby will be toast as well

    suggest either measuring them first, or doing full recap right away, having those caps dead could give ya plethora of different problems, which may include the behaviour you describe

    other than that, check current sensing, R155 looks like it may be a current shunt?

    not sure if service manuals/schematics are already available for these boards, it's still fairly "new"

    Leave a comment:


  • foundups
    replied
    Re: APC UPS units - troubleshooting

    Hi, I received the new battery and I did some tests.
    The output of the UPS stays on only for one second (same as powered with the bench power suppy)
    I noticed in the PowerChute software that the UPS is overloaded, and the input voltage is totally wrong (458V).


    And here's the warning that says that the UPS is overloaded


    Any ideas on what components I could test?
    I checked the resistors that form the resistive divider that is supposed to measure the input voltage, and they seem okay.
    Then I will check the relays and larger capacitors.
    Attached Files

    Leave a comment:


  • Behemot
    replied
    Re: APC UPS units - troubleshooting

    most of these cheap units usually don't power on correctly without working accumulator(s) connected

    also do full recap, had this recently and it's same cheaped-out crap as all them chinese, several caps were beyond death (interestingly, it was quite baked around the buzzer, which seemed to got hot buzzing constantly)

    Leave a comment:


  • foundups
    replied
    Re: APC UPS units - troubleshooting

    Thank your for your response.
    I attach some pictures I've taken.
    I hope the pictures are sufficiently clear.
    Attached Files

    Leave a comment:


  • sam_sam_sam
    replied
    Re: APC UPS units - troubleshooting

    Welcome to the forum —— thank you for trying to recover an item from the landfill

    Post some very clear pictures of the circuit board front and back and we might be able to help you with it

    “I connected the UPS to mains and I measured the voltage of the battery leads (battery not connected) and I measured 0.3V. Is this normal?”

    That depends on what type of circuit it has for the charging circuit that is the reason for asking for the pictures of the circuit board
    Last edited by sam_sam_sam; 02-19-2023, 05:43 AM.

    Leave a comment:


  • foundups
    replied
    Re: APC UPS units - troubleshooting

    Hi guys, I'm new in this forum.
    Yesterday I found an APC Back-UPS 700VA (BX700U-GR) in the landfill.
    The UPS is without battery (I ordered one).
    I brought it home and immediately did some tests:

    I connected the UPS battery lead to my bench power supply (setted at 13V).
    The UPS seems to be working but the output outlets stays on only for one second (probably because my bench power supply in not powerful enough).

    I connected the UPS to mains and I measured the voltage of the battery leads (battery not connected) and I measured 0.3V. Is this normal?

    For the time being, until I have the battery, I cannot do any more tests....

    Bye

    Leave a comment:


  • Behemot
    replied
    Re: APC UPS units - troubleshooting

    is that da BR1000I?

    always post images TO THE FORUMS

    only clean, focused and if possible, cropped to what's important (=no 5MB insane-resolution photos with half of your flat, but nothing really visible in them)

    Leave a comment:


  • iAreku
    replied
    Re: APC UPS units - troubleshooting

    Hi all,

    Ended up here jumping links when trying to fix. My APC UPS Rs1000...

    I was wondering if you would be so kind to check images of my main board to see if you spot anything "fatted" or "burned down", as I couldn't find anything weird on this unit, which aside from having been stored for a few years, I performed a battery replacement in order to bring it back to life but all I can get is power from the batteries, not from the AC/wall.

    Already checked AC in up to the main board and fuses seem to be in good shape, so I'm a bit lost right now. All I can see posted here and there is about capacitors being replaced...

    Is there a way to test capacitors with a multimeter and not dying in the try? 😂

    Here are the pics:

    https://www.dropbox.com/sh/cwszg48qd...Xaxu_FPKa?dl=0


    Thanks!

    Leave a comment:


  • Behemot
    replied
    Re: APC UPS units - troubleshooting

    don't understand no pumping stuff, is that some sexual practice?

    Leave a comment:


  • loopey
    replied
    Re: APC UPS units - troubleshooting

    Well its hard to answer if you dont say what you are confused about? Did i break rules or something?

    edit: Thought it would be nice to post a followup since u guys helped me here.
    Last edited by loopey; 11-06-2022, 07:22 AM.

    Leave a comment:


  • Behemot
    replied
    Re: APC UPS units - troubleshooting

    ?

    Leave a comment:


  • loopey
    replied
    Re: APC UPS units - troubleshooting

    Yes I came again to post result of changing caps?

    Leave a comment:


  • Behemot
    replied
    Re: APC UPS units - troubleshooting

    come again?

    Leave a comment:


  • loopey
    replied
    Re: APC UPS units - troubleshooting

    Result: SUA1500I still works, tested dod 100%

    Original caps: 5x lelon sea85 h927(m) 22uF 25v replaced with pana nhg.

    Was a pia to get some joints pumped clear. Not pretty.
    Attached Files

    Leave a comment:

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