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Hi I ordered online a voltage meter and got this tiny cute little fast refreshing pretty darn precise reliable meter. HOWEVER I am missing on all four digits the left lower vertical light piece. What could be causing this? the solder joins look okay so where exactly must I check to fix this myself?

enter image description here enter image description here enter image description here enter image description here

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    \$\begingroup\$ Where is the image or any link to your voltage meter? \$\endgroup\$
    – Aircraft
    Aug 24 '15 at 11:18
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    \$\begingroup\$ Are you able to provide a higher res image and/or identify the IC? \$\endgroup\$
    – BenG
    Aug 24 '15 at 11:31
  • \$\begingroup\$ CZAbhinav BenG Ive added the two large photos its a tiny tiny motherboard so this is as close as I could get! \$\endgroup\$
    – Sam
    Aug 25 '15 at 12:23
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    \$\begingroup\$ Knock it out moderators al of us tech users over here are trying to solve this electrical problem which is often happening, so better get a good open knowledge going here about how these things work and how to fix them, cut it out with your off-topic moderation and leave this question as well as its handy answers alone! \$\endgroup\$
    – Sam
    Aug 25 '15 at 12:26
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    \$\begingroup\$ @Sam You've been here for four years. Look around. What happens to questions like "This gadget I bought on eBay doesn't work. Why?" when there is no schematic or any kind of documentation present? -1 for the attitude. Further, how do you call one instance "often happening?" \$\endgroup\$
    – Matt Young
    Aug 25 '15 at 12:35
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One of the display segment lines (with a resistor) is broken somewhere between the die and the display insides. Chances are its crummy soldering by the manufacturer, but it could be a bad chip or display or resistor. That will cause segment E to be off on all digits.

Look at the soldering of the lines on either side of the array of 8 resistors and to the resistors themselves. In particular look at the one highlighted below:

enter image description here

Edit: I've shown the possible places (blue arrows) where a solder joint could be bad, based on the usual pinout for such an LED display, but I think I see the problem- there appears to be a cut in the trace (circled in red). The solder joints don't look obviously bad. If it is a break (look at it under a microscope or magnifier) you can scrape the solder mask off gently with a knife and bridge the gap with a bit of very thin wire and solder.

enter image description here

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  • \$\begingroup\$ Thanks for your comment, please see my two extra new photos of the backside of the motherboard of the 7 segment LED lcd. Can you draw with arrows which ones I should resolder?? \$\endgroup\$
    – Sam
    Aug 25 '15 at 12:24
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It is seem there is a broken line between the controller pin (microcontroller/microprocessor/7-segmen driver IC) and the e-pin of the seven segment. You need to trace from seven segment to the controller with multimeter (ohm-meter) to find the broken pcb track/soldering or bad resistor.

enter image description here

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  • \$\begingroup\$ Would that be the case with a 4x 7 segment? \$\endgroup\$
    – BenG
    Aug 24 '15 at 11:29
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    \$\begingroup\$ I think so. Typical multiple seven segments circuit uses multiplexing and share same a~g and dot bus \$\endgroup\$
    – Oka
    Aug 24 '15 at 11:34
  • \$\begingroup\$ Duh. brain freeze. of course you are right. and the fact it affects all of them implies the break will be between the controller and the 1st 7 seg. \$\endgroup\$
    – BenG
    Aug 24 '15 at 11:38
  • \$\begingroup\$ I see, so probably only ONE (1) connection is incomplete??? \$\endgroup\$
    – Sam
    Aug 25 '15 at 12:24
  • \$\begingroup\$ Yes. but it will be between the first 7seg and the 7seg driver so that narrows it down a bit. \$\endgroup\$
    – BenG
    Aug 25 '15 at 22:08

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