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  • miller syncrowave display missing a digit

    anyone know where I can get the lcd that displays the last digit in the display. its starting to act up...
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  • #2
    Call Digi-Key Electronics. https://info.digikey.com/index.php/email/emailWebview
    Tell them Noel sent you. When they say "who", don't be surprised.

    Comment


    • #3
      It's possible you could have something wrong besides the display itself--could be a driver chip, or power problem. Hard to tell without a schematic diagram. However, if you can find a part number on the display itself, they don't cost much and it's worth a try. You will need a well-qualified PC board soldering person with the right equipment to change it. If it turns out to be some other problem, you won't be out much money. Problem is going to be finding a part number. If you find one, check Digi-key as Noel said, or Allied, or Mouser, or TEDSS.

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      • #4
        Oh man, I just fixed a similar issue on a Miller Extreme 12V. Is it both the top and bottom last digit?

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        • #5
          Those three little transistors along the top (Q16, Q17, and Q18) probably control both LED sets. If you have a multimeter, I can walk you through what to check. Basically, 8 of the 10 pins (all but the middle ones) are connected to the corresponding pins on the numbers next to each other. The middle ones should be connected to each other on the same block, as well as the same digit (top and bottom first digit middle pins are all connected together, etc.)

          ​​​​​I am away from my shop, but will try to find a pic that better explains this.

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          • #6
            If it's the entire digit, something tells me it's either Q18 or the connection between Q18 and the LED display. Here's a picture of a seven segment display (this one is common anode, which you can tell by the direction of the diodes).
            Click image for larger version  Name:	7_segment_display_pin_outs.png Views:	0 Size:	71.1 KB ID:	603129
            To save cost, these are multiplexed together - basically each digit is turned on one at a time for a split second, and that happens long and often enough we can't tell, so it looks like all three digits are constantly lit up. I don't see a second trio of transistors like Q16/Q17/Q18 around the bottom LEDs, so I would guess those transistors drive both LED displays. Q16, Q17, and Q18 each turn on one at a time to light up the first, second, or third digit, while a driver chip lights up the right segments for each digit (there should be two driver chips). An easy way to check is to check continuity on the middle pins (com pin in the photo) of the top and bottom LED disays' same digit for all three digits. If two are connected and one's spotty, there's your issue.

            If it's not the entire digit, check pins A,B,C...G,DP on the third digit for continuity with those same pins on the second and first digit. If you can see in the space between the display and PCB, look for burnt/curled up copper traces. If continuity checks out, then it's probably the LED module. A diode test on a multimeter can confirm this.

            The one I fixed for some reason had a burned trace. I replaced the LED too, but you can find them anywhere, including Amazon. Just search for 7 segment display. You should be able to see the part number on the bottom of one (will let you know if your display is common anode or common cathode).

            When you do, try to pull the piece before you buy. I needed to use new standoff spacers as well... You might be able to get away without that, but it was faster for me to cut the components out.

            You can just search the part number on Google, Amazon, eBay, or your vendor of choice. Hope this helps...
            Last edited by jjohn76; 10-09-2019, 11:35 AM.

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            • #7
              Helps me right after well I'll be darned. Good stuff and thank you very much.

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              • #8
                No problem. It took me much longer than I care to admit to find that burnt trace... No one else should have to endure that embarrassment...
                Last edited by jjohn76; 10-08-2019, 10:12 PM.

                Comment


                • #9
                  One last thing- if you have a diode tester on your multimeter, you can check to make sure all of your segments light up. Put it in diode test mode, your positive lead on the COM pin (common anode seven segment display), and negative lead individually to A-G an DP. Each segment should light up. If none of the segments light up, reverse the leads. If they work now, you have a common cathode seven segment display.

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                  • #10
                    thanks guys. I unplugged the last digit thats acting up and swapped it out with the one plugged into the amp display. It still had some of the red missing. but the amp digit worked in the voltage slot so its definitely the lcd chip.

                    Comment


                    • #11
                      Originally posted by Noel View Post
                      Call Digi-Key Electronics. https://info.digikey.com/index.php/email/emailWebview
                      Tell them Noel sent you. When they say "who", don't be surprised.
                      on it thanks.

                      Comment


                      • #12
                        Originally posted by Aeronca41 View Post
                        It's possible you could have something wrong besides the display itself--could be a driver chip, or power problem. Hard to tell without a schematic diagram. However, if you can find a part number on the display itself, they don't cost much and it's worth a try. You will need a well-qualified PC board soldering person with the right equipment to change it. If it turns out to be some other problem, you won't be out much money. Problem is going to be finding a part number. If you find one, check Digi-key as Noel said, or Allied, or Mouser, or TEDSS.
                        it just pulls out of the pin slot. I'll chek on those vendors. thanks

                        Comment


                        • #13
                          Originally posted by jjohn76 View Post
                          If it's the entire digit, something tells me it's either Q18 or the connection between Q18 and the LED display. Here's a picture of a seven segment display (this one is common anode, which you can tell by the direction of the diodes).
                          [ATTACH=JSON]{"alt":"Click image for larger version Name:\t7_segment_display_pin_outs.png Views:\t0 Size:\t71.1 KB ID:\t603129","data-align":"none","data-attachmentid":"603129","data-size":"medium"**[/ATTACH]
                          To save cost, these are multiplexed together - basically each digit is turned on one at a time for a split second, and that happens long and often enough we can't tell, so it looks like all three digits are constantly lit up. I don't see a second trio of transistors like Q16/Q17/Q18 around the bottom LEDs, so I would guess those transistors drive both LED displays. Q16, Q17, and Q18 each turn on one at a time to light up the first, second, or third digit, while a driver chip lights up the right segments for each digit (there should be two driver chips). An easy way to check is to check continuity on the middle pins (com pin in the photo) of the top and bottom LED disays' same digit for all three digits. If two are connected and one's spotty, there's your issue.

                          If it's not the entire digit, check pins A,B,C...G,DP on the third digit for continuity with those same pins on the second and first digit. If you can see in the space between the display and PCB, look for burnt/curled up copper traces.
                          The one I fixed for some reason had a burned trace. I replaced the LED too, but you can find them anywhere, including Amazon. Just search for 7 segment display. You should be able to see the part number on the bottom of one (will let you know if your display is common anode or common cathode).

                          When you do, try to pull the piece before you buy. I needed to use new standoff spacers as well... You might be able to get away without that, but it was faster for me to cut the components out.

                          You can just search the part number on Google, Amazon, eBay, or your vendor of choice. Hope this helps...
                          I swapped out the bad one with the voltage one it it works. so its the lcd chip. thanks

                          Comment


                          • #14
                            That's great! Glad it's a simple fix. Those seven segment displays were soldered through the black standoff on the Miller Extreme 12VS, no replacement I could find had long enough leads, so in went a spacer/socket, looks like the one your display uses.

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                            • #15
                              Excellent!

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