Extech EX330 multimeter current range offset fault

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • PanicMechanic
    Member
    • May 2017
    • 47
    • Serbia

    #1

    Extech EX330 multimeter current range offset fault

    My multimeter has developed this fault, a few months ago. I tried to fix it, but had no success.

    The fault is that on the current ranges it never shows 0. Does not matter if the probes are open or shorted.
    As you can see from the pics, the offser is the same (just multiplied for other rages):

    -4.9 uA
    -0.49 mA
    -0.49 A

    I don't know what exactlly caused the fault.

    The meter had a battery leak before I noticed the fault, but I am not sure if the fault was present before that happened. I just did not noticed. The battery leaked and coroded one of the spring contacts, and one of the solder joints for the battery wire on the PCB a bit. The battery was an expencive Varta with year 2025 exparation date, of course.

    There have also been a few incidents over the years, of course. Like when I was checking the if the metal chandelier was grounded (using the resistance range), and the multimeter was showing weird readings and beeping. It turned out that the the chandelier has live with mains voltage. But the resistance range works fine.

    Now, when I was trying to repair the meter a few months ago, I changed the Op-Amp TLC27M7. It had one of the higher input offset voltage versions (I don't remember which one exactlly), but I have changed it wit the 500uV offset version (the best one).
    https://cdn.badcaps-static.com/pdfs/...b897ef51de.pdf

    It did nothing.

    The other chip is: https://cdn.badcaps-static.com/pdfs/...94ef199bcf.pdf
    I did not change that.

    Then I was cleaning the rotary switch contacts on the PCB and the switch itself, and it did show a change. I have cleaned it many times, and one time even managed to get it to show 0.02 or something, but by the time I have assembled the meter again, the fault returned. Then I tried cleaning it a few more times, without success. So, I have no idea...

    Here I found the info on trimer pots: https://www.eevblog.com/forum/testge...-extech-ex330/
    But none of them are for the current range.

    I have tried to contact Extech to ask them for help. I used a business email, but they did not reply.


    https://i.postimg.cc/28v10hnz/1.jpg

    https://i.postimg.cc/V6d6nCYP/2.jpg

    https://i.postimg.cc/d0QDQfp1/3.jpg

    https://i.postimg.cc/52V6Tym8/4.jpg

    https://i.postimg.cc/cLBrSW-D2/5.jpg

    https://i.postimg.cc/CKv5RNp4/6.jpg
    Last edited by PanicMechanic; 05-11-2021, 11:20 PM.
  • PanicMechanic
    Member
    • May 2017
    • 47
    • Serbia

    #2
    Re: Extech EX330 multimeter current range offset fault

    OK, it is fixed.

    I don't know what did it.

    I reslodered all through-hole solder joints. Cleaned the PCB. Not tightened the 3 PCB screews all the way (before I had always tightened them all the way).

    And it shows 00.00 now.

    Comment

    • jinosean
      New Member
      • Jul 2021
      • 4
      • Viet nam

      #3
      Re: Extech EX330 multimeter current range offset fault

      Can you give me the picture behind switch multimeter? Behind switch Off Vac Vdc Hz...

      Comment

      • jinosean
        New Member
        • Jul 2021
        • 4
        • Viet nam

        #4
        Re: Extech EX330 multimeter current range offset fault

        Originally posted by jinosean
        Can you give me the picture behind switch multimeter? Behind switch Off Vac Vdc Hz...
        Is it like this my picture?

        Comment

        • jinosean
          New Member
          • Jul 2021
          • 4
          • Viet nam

          #5
          Re: Extech EX330 multimeter current range offset fault

          Originally posted by jinosean
          Is it like this my picture?
          please help me to solve this problem
          Attached Files

          Comment

          • stj
            Great Sage 齊天大聖
            • Dec 2009
            • 30965
            • Albion

            #6
            Re: Extech EX330 multimeter current range offset fault

            is the problem that you dont know where the contacts go ?

            Comment

            • PanicMechanic
              Member
              • May 2017
              • 47
              • Serbia

              #7
              Re: Extech EX330 multimeter current range offset fault

              Here you are:

              https://drive.google.com/file/d/1Wk9...ew?usp=sharing

              https://drive.google.com/file/d/1WlL...ew?usp=sharing


              It seems that you are missing 2 contacts.
              Or possibly you have a lower specification model that does not have those contacts, maybe?

              Comment

              • jinosean
                New Member
                • Jul 2021
                • 4
                • Viet nam

                #8
                Re: Extech EX330 multimeter current range offset fault

                Originally posted by PanicMechanic
                Here you are:

                https://drive.google.com/file/d/1Wk9...ew?usp=sharing

                https://drive.google.com/file/d/1WlL...ew?usp=sharing


                It seems that you are missing 2 contacts.
                Or possibly you have a lower specification model that does not have those contacts, maybe?
                ok, thankyou, I think i am missing 2 contacts

                Comment

                Related Topics

                Collapse

                • Rictech
                  Panasonic SA-MAX770PU SMPSU board fault....
                  by Rictech
                  Hello everyone. 😀

                  As per thread title, this unit has a serious SMPSU fault. It blows F1001, which is a 10A M205 in the phase from the mains input.
                  Very first thing I tried, was simply replacing the fuse, but the replacement ceramic fuse blew immediately.

                  Looking at the schematic for this PSU, I then removed what I thought was the next likely candidate: D1001 - the HV main bridge rectifier.
                  This isolated the fault(no longer blows the main fuse), but does not point me to the actual fault.
                  There are no devices that have exploded or otherwise show signs...
                  08-26-2024, 01:05 AM
                • sam_sam_sam
                  ESR meter came to the rescue again today with a PLC I/O card fault
                  by sam_sam_sam
                  I have been having a fun time at work with two pieces of equipment that had shorted components or shorted component cables to machine frame
                  I would check what my multi meter was telling me about how many ohms I getting with the multi meter was telling versus the ESR was telling me about weather or not it really was a short to machine ground or not

                  One note at first we thought that it might be a bad I/O card or a malfunction PLC including me as well but I thought I would try and see if removing the I/O cables would make a difference or not and this time it did make a difference...
                  12-18-2023, 08:17 PM
                • cazi1001
                  Strange fault on Lenovo ThinkPad E14 Gen. 2
                  by cazi1001
                  Hello,
                  I have a strange fault with a Lenovo ThinkPad E14 G2 (Board No. NM-D011 Rev. 1.0).

                  The first Problem, which I fixed already, was a dead TPS65944AD (USB Type-C) controller. After I fixed this fault, all functions working fine and the notebook run very well with the charger and battery.
                  On the next day, I tied to start the notebook with the battery, but nothing happened. I started with the charger and on windows, I saw, that the battery was empty. And this was nearly impossible, because the battery was charged. I disconnected the battery and found out, that the board...
                  03-24-2024, 04:16 AM
                • spleenharvester
                  Cordless Dremel 8220 rotary tool power fault
                  by spleenharvester
                  Hi all

                  I bought this Dremel several years ago (8220 + 880 2.0Ah battery). After about a dozen light uses it developed a power fault. I asked Toolstation to start a warranty claim for me and they just refunded me in full without asking for it back instead. Would be nice to fix it instead of consigning to the dustbin.

                  It is complete luck of the drawer whether it powers on or not. Sometimes it will be completely dead, no lights no response. Switching power on and off repeatedly and/or removing and reinserting the battery will eventually make it spring to life. After that...
                  04-13-2025, 02:10 PM
                • sickboy
                  Strange CRT Fault (Sony Trinitron M1410U)
                  by sickboy
                  This is a CRT I sold a few months ago and it's came back with this weird issue. It's intermittent, but not a thermal fault, or tap sensitive - just completely random. The right side of the picture completely blanks out (picture is not shifted). The on screen display is unaffected though, so not a fault in the line section. Anyone seen anything like before in a CRT?
                  11-10-2024, 05:02 AM
                • Loading...
                • No more items.
                Working...