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    #1

    UPS and inverter questions

    Hi everyone,

    This is my first post being that I just made an account yesterday. I like the forum and there's lots of intelligent electronics people here, so I figured I would ask my questions here.


    When inverters get overloaded, which parts burn up?

    I have a couple 150w 12v inverters made by Monster Cable that were overloaded, but they still sort of work. The overload alarms on both are screaming when you turn them on. I got these from one of my brothers. He used them with a 13" TV with built-in VCR. He said the inverters would make noise when he first turned the TV on, but after that they were OK. Probably they got hot after extended use and the MOSFET's on them got weak. I don't know. I made schematics for them awhile back if anyone wants them. Not sure if it would help anyone because two of the chips have the numbers sanded off of them.

    I also have two Conext CNB750's that I got from my Dad that his boss used with his G5 Mac and they both got overloaded coming out of standby. I found broken parts on one of them, swapped it and it still doesn't quite work. There was a shorted MOSFET that I'm not sure what it's purpose was. I've got pictures of the part that is toast. There were also some traces that were burned through in spots. I can turn them on with the AC unplugged and they run on the inverter for like a second or so and then it shuts off and the lights on the front flash. Probably because the microcontroller detects a fault.

    Oh yeah, the MOSFET's that are in these UPS's are made by International Rectifier, but they said they were made specifically for Conext and they couldn't give me the specs or sell me replacements.

    I have some APC schematics that are in Russian if anyone is interested. They cover some of the Smart-UPS and the Back-UPS models. I'm having some success translating with Google and Babelfish.

    Anyway, sorry for the somewhat long post, and thanks for reading.


    Andrew
    Tags: None
    #2
    Re: UPS and inverter questions

    Here's some pictures of the shorted mosfet and the burned open trace.
    Attached Files

    Comment

      #3
      Re: UPS and inverter questions

      For some reason it will not let me upload the Russian schematics, so here's some other schematics I found.
      Attached Files

      Comment

        #4
        Re: UPS and inverter questions

        I found the Russian schematics here:
        http://www.epanorama.net/phpBB2/view...5c23208fe97c64

        Comment

          #5
          Re: UPS and inverter questions

          Hi andrew77,

          Welcome.

          You aren't being ignored. At writing this you have 32 views.
          I just don't think many people have worked on these things.
          I have some but I haven't had one break so I haven't done anything inside them.
          There are definitely a few here that have worked on them though.
          You're just waiting for one of them to trip over your post.
          -
          I am monitoring it myself to learn from your experience.
          And THANK YOU for the schematic.
          As things go if I ever actually need it I won't be able to find it.

          .
          Mann-Made Global Warming.
          - We should be more concerned about the Intellectual Climate.
          -
          Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
          - Dr Seuss
          -
          You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
          -

          Comment

            #6
            Re: UPS and inverter questions

            Originally posted by PCBONEZ
            As things go if I ever actually need it I won't be able to find it.
            Don't you just hate that!!

            It has happened to me countless times.

            Comment

              #7
              Re: UPS and inverter questions

              Thanks for the welcome, PCBONEZ.

              Here's a link to a basic UPS that someone made:

              http://electronicdesign.com/Articles...ArticleID=1029


              I sent emails to APC and Conext, but it wasn't much help since all they really want to do is sell you a new one. They said the parts were not available anymore. Seems like they have their heads in the wrong place. I asked about what the blinking lights mean, but they told me it indicated a fault. I already knew that from their FAQ.

              Maybe they're not even people and it's just machines that I sent my emails to. If you've ever talked to the Sony automated customer service you'll know what I mean.

              These UPS's that I've got have good batteries in them, but if I can't fix them, I guess I'll just have to make a UPS with some of the parts that I have. Might be fun and a good learning experience.

              Comment

                #8
                Re: UPS and inverter questions

                I don't care what APC says.
                - Parts is parts. -
                Just because ~THEY~ (APC) don't stock the parts anymore doesn't mean they aren't available at all.
                [And APC probably means whole assemblies when they say parts. Not like a transistor or a diode or a .....]

                If you can figure out the circuit then you can fix it.

                The people you are talking to are salesmen and PR people.
                The 'techs' are user-techs not electronics-techs. (If you know what I mean.)

                You'll never talk to an actual tech or engineer at a place like APC unless you have boo-coo bucks and you want something custom designed.
                Mann-Made Global Warming.
                - We should be more concerned about the Intellectual Climate.
                -
                Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
                - Dr Seuss
                -
                You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
                -

                Comment

                  #9
                  Re: UPS and inverter questions

                  I don't care what APC says.
                  - Parts is parts. -
                  Just because ~THEY~ (APC) don't stock the parts anymore doesn't mean they aren't available at all.
                  [And APC probably means whole assemblies when they say parts. Not like a transistor or a diode or a .....]

                  If you can figure out the circuit then you can fix it.

                  The people you are talking to are salesmen and PR people.
                  The 'techs' are user-techs not electronics-techs. (If you know what I mean.)

                  You'll never talk to an actual tech or engineer at a place like APC unless you have boo-coo bucks and you want something custom designed.
                  Mann-Made Global Warming.
                  - We should be more concerned about the Intellectual Climate.
                  -
                  Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
                  - Dr Seuss
                  -
                  You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
                  -

                  Comment

                    #10
                    Re: UPS and inverter questions

                    I know exactly what you mean.

                    When I talked to International Rectifier (they make the parts I need), they said they don't own the specs for the parts and so they they can't sell me the parts. I asked if they had equivalent parts and they said they don't even know what the specs are for the parts. So even having the part numbers is no help.

                    I wish there was a way to try parts on it without wasting a lot of money and parts. It really makes me want to just use the transformers and surge stuff out of it and make new guts for this UPS.

                    Do they make some kind of device that will let you find the limits of a part without breaking it?

                    Comment

                      #11
                      Re: UPS and inverter questions

                      Not that I know of (the device).

                      You might find a wealth of info including specs, equivalent parts, and cross references by entering creative variations of the part numbers into a google search.

                      .
                      Mann-Made Global Warming.
                      - We should be more concerned about the Intellectual Climate.
                      -
                      Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
                      - Dr Seuss
                      -
                      You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
                      -

                      Comment

                        #12
                        Re: UPS and inverter questions

                        I did use google for a couple hours or so to look for equivalent parts in my search, but I haven't had a whole lot of luck yet. One I did sorta find, but I don't know if it's really an equivalent part. For the 94-2358 there was a parts place (I forget which one it was) they listed IRF540NSTRL as an equivalent. It looks almost hopeless trying to find out what parts they used without someone having some kind of cross reference.

                        Comment

                          #13
                          Re: UPS and inverter questions

                          I don't care what APC says.
                          - Parts is parts. -
                          Just because ~THEY~ (APC) don't stock the parts anymore doesn't mean they aren't available at all.
                          [And APC probably means whole assemblies when they say parts. Not like a transistor or a diode or a .....]

                          If you can figure out the circuit then you can fix it.

                          The people you are talking to are salesmen and PR people.
                          The 'techs' are user-techs not electronics-techs. (If you know what I mean.)

                          You'll never talk to an actual tech or engineer at a place like APC unless you have boo-coo bucks and you want something custom designed.
                          Mann-Made Global Warming.
                          - We should be more concerned about the Intellectual Climate.
                          -
                          Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
                          - Dr Seuss
                          -
                          You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
                          -

                          Comment

                            #14
                            Re: UPS and inverter questions

                            I thought I might buy in.
                            1. For failure look in the most stressed circuitry ie where the output transistors are (probably MOSFETs).
                            2 The burnt track is in fact a fuse F1. This is quite a common trick, to reduce the track width to create a fuse. The fact that it has blown indicates a fault current. The circuit needs to be traced from this point to find out what components are supplied. You will find a short there.
                            3. Maybe your shorted transitor is the cause. Have you lifted the transistor legs to confirm a device short? When you do also check the diode alongside, make sure it is not shorted.

                            To repair any of these power circuits it is best to trace and write down the circuit to understand what is connected, in particular to that F1.

                            If you are dealing with a 12VDC inverter the switching transitors should be no less than 60 Volt rating if the output transformer is centre tapped as in your APC circuit. Determine if any transistors are connected in parallel like APC example (it has up to four on each transformer leg). The switching transistors may be MOSFETs or even bipolar in your inverter. If any are to be replaced this must be clearly established by part No. or be testing a known good device.

                            To determine the device current rating it is required to know how many transistors are attached to each transformer leg. Then we need to determine the type of transistor. Substitution is usually quite easy once this information is determined because switching applications are not critical.

                            Before proceeding further I will await what you can discover and tell me.
                            Gigabyte EP45-DS3L Ultra Reliable (Power saver)
                            Intel E8400 (3000Mhz) Bios temps. 4096Mb 800Mhz DDR2 Corsair XMS2 4-4-4-12
                            160Gb WD SATAII Server grade
                            Nvidia 8500GT 256Mb
                            160Gb WD eSATAII Server grade for backup.
                            Samsung 18x DVD writer
                            Pioneer 16x DVD writer + 6x Dual layer
                            33 way card reader
                            Windows XP Pro SP3
                            Thermaltake Matrix case with 430W Silent Power
                            17" Benq FP737s LCD monitor
                            HP Officejet Pro K5300 with refillable tanks

                            Comment

                              #15
                              Re: UPS and inverter questions

                              That's interesting how that happened.
                              Delayed double post.

                              ~~~~~~~~~~

                              Searched "94-2358" on google

                              Some RFQ sites indicate:
                              Manufacturer = INTERNATIONAL RECTIFIER -aka- "IR"

                              Then searched "INTERNATIONAL RECTIFIER" and found their site.
                              No luck on their site but there is a "contact us" link.

                              Also has a distributer list.
                              Searching each distributor's site for the PN came up with this one....
                              http://www.arrownac.com/
                              (enter the PN in their search)
                              .... having the part listed as:
                              ---
                              94-2358
                              International Rectifier
                              GEN 5 IRF540NSTRL
                              ---

                              Then searching Digikey for "IRF540NSTRL" comes up with:
                              http://search.digikey.com/scripts/Dk...IRF540NSTRL-ND
                              [read the spec table]
                              and a link to the datasheet back on IR's site:
                              https://cdn.badcaps-static.com/pdfs/...19cadae6b5.pdf

                              Unfortunately Digikey doesn't have stock but Newark does:
                              http://www.newark.com/jsp/search/bro...F540NSTRL&Ntx=

                              ~~ Persistence and creativity pays off.

                              .
                              Mann-Made Global Warming.
                              - We should be more concerned about the Intellectual Climate.
                              -
                              Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
                              - Dr Seuss
                              -
                              You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
                              -

                              Comment

                                #16
                                Re: UPS and inverter questions

                                Oh,
                                The PN variation with "PBF" means "PB"-Lead "F"-Free
                                Any other characters after that are packaging information.
                                Mann-Made Global Warming.
                                - We should be more concerned about the Intellectual Climate.
                                -
                                Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
                                - Dr Seuss
                                -
                                You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
                                -

                                Comment

                                  #17
                                  Re: UPS and inverter questions

                                  https://ec.irf.com/v6/en/US/adirect/...me=IRF540NSTRL
                                  Mann-Made Global Warming.
                                  - We should be more concerned about the Intellectual Climate.
                                  -
                                  Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
                                  - Dr Seuss
                                  -
                                  You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
                                  -

                                  Comment

                                    #18
                                    Re: UPS and inverter questions

                                    Good detective work. So we have define a 100V 33A N Channel MOSFET. Thats a good start. How many are there in the inverter?
                                    Gigabyte EP45-DS3L Ultra Reliable (Power saver)
                                    Intel E8400 (3000Mhz) Bios temps. 4096Mb 800Mhz DDR2 Corsair XMS2 4-4-4-12
                                    160Gb WD SATAII Server grade
                                    Nvidia 8500GT 256Mb
                                    160Gb WD eSATAII Server grade for backup.
                                    Samsung 18x DVD writer
                                    Pioneer 16x DVD writer + 6x Dual layer
                                    33 way card reader
                                    Windows XP Pro SP3
                                    Thermaltake Matrix case with 430W Silent Power
                                    17" Benq FP737s LCD monitor
                                    HP Officejet Pro K5300 with refillable tanks

                                    Comment

                                      #19
                                      Re: UPS and inverter questions

                                      There's 3 of these 94-2358, there's 4 of these 94-4311 and 4 of these other p19nb2. Here's some pictures. The first one is the 94-2358. The second and third is 94-4311. The fourth and fifth is p19nb2.
                                      Attached Files

                                      Comment

                                        #20
                                        Re: UPS and inverter questions

                                        The 94-4311 are paralleled, but I'm not real sure what they do. They're connected to a 35v 3300uf capacitor, so maybe they're the part that handles the DC from the batteries. The batteries are two 12v run in series.

                                        The 94-2358 I haven't figured out yet. Pretty hard to tell what's going on since they have so many tiny traces that are connected on both sides of the board. They have a couple decent sized diodes in between two of them. Two of them run off two of the transformer leads that say CLAMP WINDING on them. The third one I'll have to look at a lot longer to figure out.

                                        The p19nb2 are probably the inverter. They're wired in series. They have a 250v 47uf capacitor near them. There's also a big inductor that is included in that circuit.

                                        I'll look at it some more and post some more pictures after I take a break.

                                        Comment

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