What's inside a Blob?

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  • Crystaleyes
    Badcaps Veteran
    • Sep 2021
    • 493
    • Brazil

    #1

    What's inside a Blob?

    Is something I had often wondered.

    After picking up a DMM with a fried selector circuit trace, I thought I'd have a look and find out.


    And now you know too


    Tell you one thing, it's some seriously tough shit.
    Attached Files
    Last edited by Crystaleyes; 01-20-2023, 12:33 PM.
  • R_J
    Badcaps Legend
    • Jun 2012
    • 9514
    • Canada

    #2
    Re: What's inside a Blob?

    That is/was the microprocessor die that was under that blob

    Comment

    • Crystaleyes
      Badcaps Veteran
      • Sep 2021
      • 493
      • Brazil

      #3
      Re: What's inside a Blob?

      Yeah.

      I had just always wondering why it was hidden under a blob?

      Judging by the toughness of the resin, I would say that is to ensure that no-one can ever do a repair

      Comment

      • stj
        Great Sage 齊天大聖
        • Dec 2009
        • 30902
        • Albion

        #4
        Re: What's inside a Blob?

        it's an ICL7106
        a classic chip used in most old lcd meters.
        there is also an ICL7107 for use with led displays.

        Comment

        • stj
          Great Sage 齊天大聖
          • Dec 2009
          • 30902
          • Albion

          #5
          Re: What's inside a Blob?

          Originally posted by Crystaleyes
          Yeah.

          I had just always wondering why it was hidden under a blob?

          Judging by the toughness of the resin, I would say that is to ensure that no-one can ever do a repair
          the chip is cheaper without it's package.

          Comment

          • Crystaleyes
            Badcaps Veteran
            • Sep 2021
            • 493
            • Brazil

            #6
            Re: What's inside a Blob?

            Originally posted by stj
            it's an ICL7106
            a classic chip used in most old lcd meters.
            there is also an ICL7107 for use with led displays.
            I see. That makes sense as I've seen them in more DMM's than I can remember, but that's interesting to know, as I had assumed it was where 'all the magic' happened.

            Just out of interest, are these programmable? I mean, if they are a display controller, then how many display variaations are there for example?

            I'd thought it would be really easy to scrape the blob away to see but it was feckin hard work!
            Won't be doing it again in a hurry.

            Comment

            • eccerr0r
              Solder Sloth
              • Nov 2012
              • 8658
              • USA

              #7
              Re: What's inside a Blob?

              No they are not programmable, and likely the board was made to take the bare die plus encapsulation or a QFP hence the pads on the board...

              The 7106/7107 are integrated LCD/LED controllers plus the ADC all in one monolithic chip.

              BTW I've seen some other integrated LCD+ADCs so it may not be specifically a intersil 7106 or its clones, ... so be careful making assumptions.

              Comment

              • R_J
                Badcaps Legend
                • Jun 2012
                • 9514
                • Canada

                #8
                Re: What's inside a Blob?

                Some information for the O.P.
                It is called Chip-on-Board, here is a link to how they are done: https://learn.sparkfun.com/tutorials...s-are-made/all
                Last edited by R_J; 01-20-2023, 07:11 PM.

                Comment

                • stj
                  Great Sage 齊天大聖
                  • Dec 2009
                  • 30902
                  • Albion

                  #9
                  Re: What's inside a Blob?

                  Originally posted by eccerr0r
                  No they are not programmable, and likely the board was made to take the bare die plus encapsulation or a QFP hence the pads on the board...

                  The 7106/7107 are integrated LCD/LED controllers plus the ADC all in one monolithic chip.

                  BTW I've seen some other integrated LCD+ADCs so it may not be specifically a intersil 7106 or its clones, ... so be careful making assumptions.
                  it wasnt an asumption, i have the DT830 schematic
                  Attached Files

                  Comment

                  • redwire
                    Badcaps Legend
                    • Dec 2010
                    • 3900
                    • Canada

                    #10
                    Re: What's inside a Blob?

                    Chip-on-board still has the packaged part's pinout. OP you could check the pinout verses TC7106C in 44-pin QFP or PLCC package, what ever fits.
                    https://www.instructables.com/Replac...With-a-44-Pin-
                    Or just toss it and get a new multimeter? These low dollar multimeters have minimal input protection and are easily fried.

                    Comment

                    • eccerr0r
                      Solder Sloth
                      • Nov 2012
                      • 8658
                      • USA

                      #11
                      Re: What's inside a Blob?

                      in this case it is a 7106/7116/7136, but I have a DMM with a COB that's not one of these... it's some taiwan company I forget, and didn't look like an intersil clone.

                      Comment

                      • jiroy
                        Badcaps Legend
                        • Jun 2016
                        • 2416
                        • Lebanon

                        #12
                        Re: What's inside a Blob?

                        Those blobs are useful for light weight devices , like Christmas trees lights or tiny multimeters etc .. Mostly can be replaced .

                        Comment

                        • Crystaleyes
                          Badcaps Veteran
                          • Sep 2021
                          • 493
                          • Brazil

                          #13
                          Re: What's inside a Blob?

                          Originally posted by R_J
                          Some information for the O.P.
                          It is called Chip-on-Board, here is a link to how they are done: https://learn.sparkfun.com/tutorials...s-are-made/all
                          Wow.. That is fascinating!

                          I never imagined that they had actual wires inside.


                          Nice one. Thank you for that
                          Last edited by Crystaleyes; 01-21-2023, 09:46 AM.

                          Comment

                          • Crystaleyes
                            Badcaps Veteran
                            • Sep 2021
                            • 493
                            • Brazil

                            #14
                            Re: What's inside a Blob?

                            Originally posted by redwire
                            Chip-on-board still has the packaged part's pinout. OP you could check the pinout verses TC7106C in 44-pin QFP or PLCC package, what ever fits.
                            https://www.instructables.com/Replac...With-a-44-Pin-
                            Or just toss it and get a new multimeter? These low dollar multimeters have minimal input protection and are easily fried.
                            It was bought for a quid from a street seller so not a problem. I've already striped down what might be reusabe in the future and the binned the board

                            Comment

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