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  • Caps

    List me some reasons for wireway Sweep Caps blowing.

    Ive covered most of em i think. Want to make sure. List all known reasons wireway sweep caps can blow.

    Thankee-sai Gunslingers,

    The Crimson King
    The impossible often has a kind of integrity to it which the merely improbable lacks.

  • #2
    Re: Caps

    How many are you looking for??

    Comment


    • #3
      Re: Caps

      Incorrect wiring, debris shorting across terminals, or failed components in:

      Motor terminal board(s)
      Motor plug/receptacle
      Motor cable
      C1
      Terminal Strip
      Capacitors/resistor
      SWSR
      Whatever switch-replacement gizmo might be present
      Sweep contactor in chassis

      Is this a new problem?

      Comment


      • #4
        Re: Caps

        A cap blows (literally) when you draw much more continuous current through it than it can handle (and the longer, the worse), or you put more voltage on it than it can handle.

        Although a cap is predominately a reactive device, it has some internal resistance. Current through this resistance makes heat inside the cap. In a liquid electrolytic cap (which the motor caps are), too much heat boils the liquid and boom she goes. Excessive voltage jumps the gap inside the cap and usually results in an internal short, which in turn produces heat and boils the electrolyte.

        The bigger the cap, the more liquid, and the more party fun (and mess) results when it blows.

        Over time, the electrolyte dries up a bit and the cap's ability to withstand voltage is reduced. Also, the internal resistance tends to increase, making it warm up more and hence withstand less continuous current.

        Chad mentioned several items which can lead to the above. I would bet on contactor contacts (particularly brake contacts connecting when they shouldn't) and faulty start switch causing run winding being engaged continuously.

        Andrew.

        Comment


        • #5
          Re: Caps

          Help me some more guys, please.

          I have been told that the sw reverse switch is supposed to be rated at 1/2 horse. The sw run switch at 1/4 horse.

          Ive been taught that even when the sw reverse switch is not being used, it is still run through to complete the circuit.

          So, i took the control box face off the back and started investigating what HP rating all my sw reverse switches had.

          I found many that were simply unmarked, many of the sweep reverses were 2/3 hp (?!) and some were even 1/4 hp rated.

          Guide me, children of the night. What can i get away with, what should i worry about, and why do i like frankenberry more than count chocula?
          The impossible often has a kind of integrity to it which the merely improbable lacks.

          Comment


          • #6
            Re: Caps

            AMF did some really strange things with 82/70s. A couple of our machines had thicker wires going to the motors (#12 multistrand) than they did in the front wireway off of the RS male plug... we had a couple of RS's that had #16 wire on them to power the whole machine! Needless to say, 2 changed it to #12... and even at that... I would use #12 wire to run just ONE of the motors on this machine... AMF uses #14 and #16 to power the whole shebang.

            That being said, the switch ratings vary greatly... I had some that were rated for 1/3HP that had heavier contacts in them than ones rated for 1/2HP. Depends on the manufacturer and the way they tested their product to set the power ratings.
            <span style="font-style: italic">Educatio est omnium efficacissima forma rebellionis</span>

            Comment


            • #7
              Re: Caps

              Yes, the sweep reverse switch is used in the motor start circuit, I have seem faulty switches cause start problems and blown capacitors. I would lean toward C1 miswiring on the neutral side of the motor.

              Ratings, as G sez vary by manufacturer.

              What kinda chassis are you running?
              Please.....follow the instructions!!

              John
              804-240-4982

              Comment


              • #8
                Re: Caps

                Single board MP John.

                I have to assume, what with the many and varied different HP rated Sw Rev switches already in place, that that may not have been the fault. All of the other pinsetters with "incorrect" sw reverse toggles have not and do not regularly blow caps...

                Found some metal debris in the wireway. Impossible to tell if it was touching anything, as i found it all with the help of a point blank air-gun blast.

                Tried a different chassis, put my last two new caps in, and ordered some sw rev switches that should arrive tomorrow, just in case.

                We shall see.
                The impossible often has a kind of integrity to it which the merely improbable lacks.

                Comment


                • #9
                  Re: Caps

                  I know of one thing that WILL blow a sweep cap - if the circuit is miswired to try to run it both ways at once. The one time this happened to me (guy said the chassis was OK, but no mask lights... [img]/content/btubb/images/%%GRAEMLIN_URL%%/mad.gif[/img] ), the sweep contactor pulled in, it hummed loudly for a second or two and *bam* confetti city [img]/content/btubb/images/%%GRAEMLIN_URL%%/blush.gif[/img] and me having to change my drawers...the problem with that one was in the wiring to the brake contacts. Also if they are the original AB contactors, make really sure the lowers aren't sticking, welded together, or have a spring missing (on the contact). If you want a really good tester to check caps get an ESR meter. Here is the one I have:

                  <a href="http://www.mcminone.com/product.asp?catalog%5Fname=MCMProducts&amp;product %5Fid=72%2D6355" target="_blank"><a href="http://www.mcminone.com/product.asp?catalog%5Fname=MCMProducts&amp;product %5Fid=72%2D6355" target="_blank"><a href="http://www.mcminone.com/product.asp?catalog%5Fname=MCMProducts&amp;product %5Fid=72%2D6355" target="_blank"><a href="http://www.mcminone.com/product.asp?catalog%5Fname=MCMProducts&amp;product %5Fid=72%2D6355" target="_blank"><a href="http://www.mcminone.com/product.asp?catalog%5Fname=MCMProducts&amp;product %5Fid=72%2D6355" target="_blank"><a href="http://www.mcminone.com/product.asp?catalog%5Fname=MCMProducts&amp;product %5Fid=72%2D6355" target="_blank"><a href="http://www.mcminone.com/product.asp?catalog%5Fname=MCMProducts&amp;product %5Fid=72%2D6355" target="_blank"><a href="http://www.mcminone.com/product.asp?catalog%5Fname=MCMProducts&amp;product %5Fid=72%2D6355" target="_blank"><a href="http://www.mcminone.com/product.asp?catalog%5Fname=MCMProducts&amp;product %5Fid=72%2D6355" target="_blank">http://www.mcminone.com/product.asp?catalog%5Fname=MCMProducts&amp;product %5Fid=72%2D6355</a></a></a></a></a></a></a></a></a>

                  WELL worth the money! I have a high end B&amp;K cap. tester that showed a cap was "good" when this meter showed it to be bad. I have found a lot of "good" caps are really bad...saves me a ton of time. [img]/content/btubb/images/%%GRAEMLIN_URL%%/smile.gif[/img]

                  Jon
                  I've had enough of hope & chains.

                  Comment


                  • #10
                    Re: Caps

                    Hey Monkey, are you trying to fix a problem, or just learning, grasshopper?

                    The SWSR switch is part of the motor's start circuit and carries the full starting and stopping current of the motor, via the caps and related circuitry. The starting current is considerably larger than the running current - around 20A versus 4A or so.

                    The start/stop current is only maintained for a very short time (starting takes around a fifth of a second, and stopping takes even less time).

                    Switches (and relays and contactors) that are used in motor applications have two ratings: continous current and horsepower. The continous current rating represents the maximum amount of current you can pull through the switch continously, forever, without making it overheat and die.

                    The HP rating on the other hand is a short-term rating and takes into account the higher, but temporary, starting current of the motor. If it doesn't have a HP rating, it might not be suitable for motor applications (but that's not a hard and fast rule, and if you have switches that are unmarked, you would know very quickly if they couldn't handle the task, so I wouldn't worry about it for existing used switches).

                    The HP rating corresponds the rating of the motor that can be handled by the switch. 1/3HP motor would require a 1/3HP switch, or greater (2/3HP is therefore fine for a 1/3HP motor like an 8070 combo).

                    So, a given switch may handle inrush currents very well (high HP rating), but have a lower continous current rating. The combination of the two relate to the contact design (size, cross-section, thickness, material, enclosure, etc, etc). Also, the size of the contacts may not be proportional to the HP rating (or even the cont. current rating, depending on the material used for the contacts).

                    The rating of the SWSR only affects whether the SWSR will overheat and fail prematurely (i.e. if it's too low). It doesn't affect the rest of the circuit (well, until it fails, that is).

                    But, as Steve pointed out, and Chad pointed out earlier, the SWSR switch, if faulty or miswired can cause overloading of the start circuit (and hence a blown cap).

                    As for the SWS, it has no baring on the motor circuit at all. It just completes the sweep contactor (24VAC) circuit. It therefore needs a lesser rating (anything higher than 1/10HP would be fine, so 1/4 is certainly fine).

                    Cheers,
                    Andrew.

                    P.S. You asked. [img]/content/btubb/images/%%GRAEMLIN_URL%%/wink.gif[/img]

                    Comment


                    • #11
                      Re: Caps

                      Sorry, I took so long with that last post that I missed the answer to my first question.

                      So I gather then, that the machine works for a while but eventually blows a cap? And this keeps happening?

                      I would suggest what you have already done - i.e. change the chassis and see how it goes (eliminates the contactor). Also (if it does it again), you could change the start switch and see how that goes too.

                      Andrew.

                      Comment


                      • #12
                        Re: Caps

                        Andrew,

                        That's the smartest thing I've ever heard anyone say about anything.

                        You are elite. If the Tech of the Year was distributed in various categories, I would vote you immediately for the Electrical Wizardry category.

                        Thanks.
                        The impossible often has a kind of integrity to it which the merely improbable lacks.

                        Comment


                        • #13
                          Re: Caps

                          Originally posted by *70*PinMonkey:
                          Andrew,

                          If the Tech of the Year was distributed in various categories, I would vote you immediately for the Electrical Wizardry category.
                          <font size="2" face="Verdana, Helvetica, sans-serif">I'll definitely second that [img]/content/btubb/images/%%GRAEMLIN_URL%%/smile.gif[/img]

                          Comment


                          • #14
                            Re: Caps

                            Well, shucks, I'm turning Kegel Ion red.

                            Of course, I'd be in very good company in that category.

                            Thanks fellas.

                            Comment


                            • #15
                              Re: Caps

                              Is Triac your twin brother? [img]/content/btubb/images/%%GRAEMLIN_URL%%/laugh.gif[/img]
                              So it goes.

                              Comment

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