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Netgear Prosafe JGS516 switch with Delta Electronics ADP-40VP PSU board (fixed)

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    #21
    Re: Netgear Prosafe JGS516 switch with Delta Electronics ADP-40VP PSU board (fixed)

    I had a Delta ADP-40VP in a Dell PowerConnect 2716 go back today, had been running for years, just moved the power cord to another outlet and it wouldn't start up again. No burnt smell, no output voltage at all. I read this thread, replaced the C5 capacitor, 47uF 25V and voila it came back to life!

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      #22
      Re: Netgear Prosafe JGS516 switch with Delta Electronics ADP-40VP PSU board (fixed)

      Newbie to the site, but not to electronics being 72 years on this planet.

      Glad I found this forum as this morning our household Netgear 1GHz switch decided not to play once the computer room (spare bedroom/my play area) power was switched on.
      No sign of life, no smell of toasted electronic bits, just nothing.

      Obvious check of main fused plug lead: all fine, though I did find the original supplier of this second-user item had fitted a 13A fuse! Now down to a more sensible 3A.

      Swap the box out for an older spare Kingston 10/100 switch and at least network connectivity restored throughout the house.

      Back to the Netgear JGS 516. O.K. time to get the lid off and look for anything obviously amiss inside.

      What a palaver. Mine has the little right angle rack mounting brackets fitted on the sides. If you don't take these off you can't separate the box top and bottom to open it as it is a clamshell design and the mounting screws go right through both leaves of the clamshell (I found that out last!)

      4 tiny crosshead screws hold each bracket on. They have probably been fitted while the paint was wet by a guy with an air-tool set to do up lorry wheel nuts ! Make sure your screwdriver is a VERY good fit and has a head you can really grip! I ended up cheating and using my trusty straight-blade screwdriver that has a really hard blade and good shaft and managed to break the death grip of the screws.

      Then you can take out the little crosshead screws around the perimeter of the box plus don't forget the 2 (one each side) on the sides of the front cover.

      Pull the front cover plate forward a little and you can then tease the clamshell apart.
      Inside very nice, tidy, minimal design. All powered from the Delta Electronics switch-mode psu sitting alongside the main board. It does have a rating plate on it: 5V 8A output.

      Well if push comes to shove temporarily I could always power the mainboard from another power supply of the same rating, so let's see if we can find anything obviously dead or dying in the psu.

      Nothing volunteered to be the culprit on that one. No obvious overheating, no obvious dry joints. Finally found the onboard fuse after disconnecting the psu (a simple plug at each end). The fuse is an encapsulated part near the incoming mains socket on the psu board. Looks a bit like a capacitor. It is soldered in. You can't therefore just remove it. However an ohms check across its pins revealed it was still alive and well.

      Now switch mode psu modules come in a bewildering number of ways that a designer can create one, so once you've eyeballed it and found no obvious dead things you are down to shotgunning by substitution (helps if you know the obvious ones to hit first such as capacitors and diodes) or you need a circuit diagram. Some makers make them available, others treat them as a state secret and even the internet won't find you one.

      Ever optimistic I gave the internet a go and found you guys.
      Guess what? Yep, the start up capacitor (47uF 25V) was the culprit. I changed it out and all is now well.

      As noted elsewhere it was caught up in the yellow goop which holds down the big capacitor next to it, but sliding the tip of a narrow craft knife down the side of the start-up capac released it easily from the mechanical grip of the goo. Then I turned the board over and desoldered it using a proper solder-sucker/pump (the ones with the spring-loaded plunger) and a fine -tipped iron.

      Be careful when soldering/desoldering on the psu board, you need to work quickly. There are lots of tiny surface mounted components around the spot where you are working If you let heat run away down the tracks because you hang around too long other things may desolder themselves or just become poor connections.

      SAFETY:
      Word of warning to real newbies doing this: switch-mode psu circuits have capacitors of high value (which means they can store lots of energy) and often of high voltage too (which means the belt is even bigger when it bites you).

      Disconnecting a psu you have just had powered up either to see if it works at all or to see if your repair has fixed it and then picking it up and handling it with you fingers all over the board (apart from the possibility of you damaging it via electrostatic discharge) gives it a great chance to damage you if those capacitors haven't discharged.

      Leave it for a few minutes and even then try to avoid sticking your fingers where they will bridge contacts on the board. You can't always rely on on-board circuitry discharging the capacs if the board is faulty.

      Soldering/desoldering is thus even more fun if the board has recently been powered up. Use a proper desoldering pump and do one leg at a time. Flooding solder across both terminals of the capac so you can pull it out while the solder is molten (and we've all done it in a push) isn't a good idea. If the capac discharges into the molten solder try remembering that your face and your eyeballs are probably in the line of flight of the solder. Remember those protective glasses we never wear?

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        #23
        Re: Netgear Prosafe JGS516 switch with Delta Electronics ADP-40VP PSU board (fixed)

        4 days ago my Netgear 16 port switch power supply failed which lead me to this forum. I followed the advice from this post and replaced the 47uF 25V startup capacitor. And now the power supply and switch works again! Thank you for the information.

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          #24
          Re: Netgear Prosafe JGS516 switch with Delta Electronics ADP-40VP PSU board (fixed)

          Not so lucky for me so far. My Netgear GS716T died last night and it has a Delta ADP-40VP power supply in it the same as the others on here. Found this forum thread and promptly popped out the 47uf cap and replaced it and no difference...still dead. Pulled out the 400V 100uf filter cap and it's got 90uf...bought a new one...new one is 97uf so not sure if that's the issue. Kept tracing and noticed the big resistor at the filter cap legs (Orange, Orange, Silver, Gold) My resistor chart says 0.33 Ohms +/- 5%. When I measure across it I get 22kOhms.
          Before I rush out and buy this one too...is it supposed to be 0.33 Ohms? I'm pretty sure 22k Ohms is wrong.

          thanks for any advice.

          Update...found this pic and I'm pretty sure this is the same type of resistor. Can I measure this type the normal method...resistance setting on my fluke?
          Attached Files
          Last edited by AlTaiRius; 02-01-2022, 11:29 PM. Reason: Extra Pic

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            #25
            Re: Netgear Prosafe JGS516 switch with Delta Electronics ADP-40VP PSU board (fixed)

            the resistor acts as a fuse - something is probably shorted.
            most likely the big chip/transistor hiding behind the white stuff

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              #26
              Re: Netgear Prosafe JGS516 switch with Delta Electronics ADP-40VP PSU board (fixed)

              Originally posted by stj View Post
              the resistor acts as a fuse - something is probably shorted.
              most likely the big chip/transistor hiding behind the white stuff
              Do you think it's the part I circled that's most likely to have taken out the resistor?
              Attached Files

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                #27
                Re: Netgear Prosafe JGS516 switch with Delta Electronics ADP-40VP PSU board (fixed)

                probably, you can meter for shorts between its pins on the other side of the board.

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                  #28
                  Re: Netgear Prosafe JGS516 switch with Delta Electronics ADP-40VP PSU board (fixed)

                  If that resistor blew, chances are good for the FET to be blown too. Now if the FET blew too, you have to check the whole gate drive circuit of the FET.

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                    #29
                    Re: Netgear Prosafe JGS516 switch with Delta Electronics ADP-40VP PSU board (fixed)

                    Same power supply on a Dell PowerConnect 2716 and replacing the 47uF 25V capacitor brought it back to life. Thanks

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                      #30
                      Re: Netgear Prosafe JGS516 switch with Delta Electronics ADP-40VP PSU board (fixed)

                      Found this thread after my Dell 2724 did the exact same thing as OP. Will try replacing that small cap and report back (might be a few years though).

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                        #31
                        replacing the 47uF 25V this working, thank you

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