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    Fluke rubber capacitors.

    I was using my Fluke 75 yesterday and it gave a low batt sign. I bought it around 1986 at Fry's in San Jose. I opened it up to throw a new 9-volt batt in it and noticed two yellow capacitors which looked like they had a black stripe running top to bottom on both sides. They looked like large tantalums from the shape. I put my finger on them and found the coating was rubbery and the stripe was a crack. Any ideas what they are and are they going to be a Problem? Meter seems to work fine especially with a new battery. I should send it to fluke for a new display the LCD is looking very washed out but still readable.
    sigpicThe Sky Is Falling

    #2
    Re: Fluke rubber capacitors.

    i dont know about the caps, but the display is probably fine - it's the zebrastrip that usually fails.

    Comment


      #3
      Re: Fluke rubber capacitors.

      series 1,2 or 3?
      Attached Files

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        #4
        Re: Fluke rubber capacitors.

        These?
        Attached Files
        Things I've fixed: anything from semis to crappy Chinese $2 radios, and now an IoT Dildo....

        "Dude, this is Wyoming, i hopped on and sent 'er. No fucking around." -- Me

        Excuse me while i do something dangerous


        You must have a sad, sad boring life if you hate on people harmlessly enjoying life with an animal costume.

        Sometimes you need to break shit to fix it.... Thats why my lawnmower doesn't have a deadman switch or engine brake anymore

        Follow the white rabbit.

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          #5
          Re: Fluke rubber capacitors.

          I'm not sure about the series. I looked it up online and found what you meant by zebrastrips. Mine has light colored ones so maybe series 2? I'll give it a clean and see what happens. Hope the display doesn't completely die, that's my usual luck. Thanks.
          sigpicThe Sky Is Falling

          Comment


            #6
            Re: Fluke rubber capacitors.

            Yeah, that's what they look like goon. Not exact but real close. Are they supposed to be split?
            Last edited by rhomanski; 03-01-2016, 10:07 PM.
            sigpicThe Sky Is Falling

            Comment


              #7
              Re: Fluke rubber capacitors.

              Originally posted by rhomanski View Post
              Yeah, that's what they look like goon. Not exact but real close. Are they supposed to be split?
              Yes. Breakdown voltage of the gap is 2kv
              Things I've fixed: anything from semis to crappy Chinese $2 radios, and now an IoT Dildo....

              "Dude, this is Wyoming, i hopped on and sent 'er. No fucking around." -- Me

              Excuse me while i do something dangerous


              You must have a sad, sad boring life if you hate on people harmlessly enjoying life with an animal costume.

              Sometimes you need to break shit to fix it.... Thats why my lawnmower doesn't have a deadman switch or engine brake anymore

              Follow the white rabbit.

              Comment


                #8
                Re: Fluke rubber capacitors.

                Roger that. Not a problem then. I was thinking I might have to replace them. Thanks.
                sigpicThe Sky Is Falling

                Comment


                  #9
                  Re: Fluke rubber capacitors.

                  Originally posted by rhomanski View Post
                  Roger that. Not a problem then. I was thinking I might have to replace them. Thanks.
                  They are a rather common sight on really old fire alarm systems.
                  Things I've fixed: anything from semis to crappy Chinese $2 radios, and now an IoT Dildo....

                  "Dude, this is Wyoming, i hopped on and sent 'er. No fucking around." -- Me

                  Excuse me while i do something dangerous


                  You must have a sad, sad boring life if you hate on people harmlessly enjoying life with an animal costume.

                  Sometimes you need to break shit to fix it.... Thats why my lawnmower doesn't have a deadman switch or engine brake anymore

                  Follow the white rabbit.

                  Comment


                    #10
                    Re: Fluke rubber capacitors.

                    Originally posted by rhomanski View Post
                    I was using my Fluke 75 yesterday and it gave a low batt sign.
                    The Fluke 70 series I, II and III have an outstanding 2,000 (two thousand) hour battery life. Once the low battery comes on, replace it immediately otherwise you can get funny and incorrect readings.

                    I opened it up to throw a new 9-volt batt in it and noticed two yellow capacitors which looked like they had a black stripe running top to bottom on both sides.
                    As goontron noted, they are spark gaps. See this recent and relevant discussion over at eevblog where I just finished posting some comments.

                    http://www.eevblog.com/forum/repair/...pair-teardown/

                    I should send it to fluke for a new display the LCD is looking very washed out but still readable.
                    Faded digits on early Fluke series are a known problem. See

                    http://mrmodemhead.com/blog/fluke-8x-faded-lcd/
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                      #11
                      Re: Fluke rubber capacitors.

                      Originally posted by rhomanski View Post
                      I bought it around 1986 at Fry's in San Jose.
                      Great to see it still working after 30 years.
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                        #12
                        Re: Fluke rubber capacitors.

                        That's also using it for years taking voltage and watching all sorts of signals at work.

                        I was working an autopilot once. I tapped in to an lvdt and watched it as the stabilizer was trimmed up, looked good, trim down, good, except the voltage never went away after it stopped moving. It would do it everytime. No wonder the autopilot would kick off. That lvdt is internal, had to replace the whole actuator.

                        I Dropped it many.many times. Can't say enough how good that 75 has been. I also have a simpson 360 from the same period. I've never dropped it, doubt it would have survived as well if I had.
                        sigpicThe Sky Is Falling

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                          #13
                          Re: Fluke rubber capacitors.

                          Well, I pulled the display. That rubber was really stuck to the circuit board. I cleaned the solder pads and the end of the rubber. I tried to get the rubber off the contacts on the glass but it wouldn't come off. I was concerned about pulling the contact off with the rubber so I didn't push it. Put it all back together. Good news is it still works, bad news is no change, still looks washed out. It's still usable so I'll leave it alone. Thanks everyone.
                          sigpicThe Sky Is Falling

                          Comment


                            #14
                            Re: Fluke rubber capacitors.

                            Originally posted by rhomanski View Post
                            I cleaned the solder pads and the end of the rubber.
                            Did you use IPA? Sometimes it might take multiple cleaning applications to get it completely clean. If that doesn't work, then the original zebra strip may have degraded after 30 years.

                            I have read stories of people boiling their zebra strips to make them expand, but like modemhead, I have never tried it.

                            http://www.electro-tech-online.com/t...ectors.110678/

                            Another story I read is to add solder onto the pcb so that the contacts are raised a bit to make better contact with the old zebra strip. Right now, I can't find that post.

                            Sometimes I see replacement zebra strips being sold on ebay. Here is one for $20 USD + free shipping.

                            http://www.ebay.com/itm/191806766518

                            Is it worth $20 USD? Only you can decide.
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                              #15
                              Re: Fluke rubber capacitors.

                              Found the stories about adding solder to the pcb at modemhead's blog in the comments section

                              http://mrmodemhead.com/blog/fluke-8x-faded-lcd/

                              "Chris Kay says:
                              December 4, 2013 at 10:44 pm
                              just did the cleaning of the zebra strips on my 73 iii fluke meter I noticed the display pcb pads were not very even, or missing solder so i either sucked off clean a couple, added a little fresh solder, even up the height of pads, cleaned pads as well very well with iso as well as zebra strips and glass. display nice and dark like brand new."

                              "Adam Wong says:
                              August 8, 2015 at 12:38 am
                              I have a Fluke 12 DMM that is 25 years old. The buttons stopped working because an elastomeric connector wasn't making good contact with the PCB. Cleaning did not fix it. The way I fixed it was to “touch up” the PCB with solder making sure that the solder on the contact points was a little thicker than original. The idea was to increase contact pressure between the elastomeric and the PCB. DMM works perfectly now."
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