Hey, I built a 2 digit counter with cd4026's. On the first digit (one's place), the E, F, and G segments only light up on 6 and 8, and on the ten's place digit, the D, E, and G segments are permanently lit. My multimeter shows a short between those segments and the power rail, but the solder joints look fine. Can anyone help me fix this?

 

What is the part number of the display?

 

Hey, I built a 2 digit counter with cd4026's. On the first digit (one's place), the E, F, and G segments only light up on 6 and 8, and on the ten's place digit, the D, E, and G segments are permanently lit. My multimeter shows a short between those segments and the power rail, but the solder joints look fine. Can anyone help me fix this?

Three things come to mind.
You have no current limiting resistors in line with the LED's.
The LED's need to be very High Efficiency, Low current ones.
The CD4026's are not designed to drive displays directly.

 

Hi 488
Please post a clear photo of the rear faces of the PCB's,
E
corrected user name error..

 

What is the part number of the display?

I don't know the part number. it's these:
Amazon.com: uxcell 10 Pcs Common Cathode 10-Pin 1 Bit 7 Segment 0.56" Red LED Display Digital Tube : Industrial & Scientific

 

Hi 488
Please post a clear photo of the rear faces of the PCB's,
E
corrected user name error..

 

hi 88,
The PCB track cuts are not clean, suspect copper links, check and clean up, the cuts and ensure that the adjacent tracks are not linked with unintentional solder bridges.
Give them a good clean and check.

Use a magnifying eyeglass

E

Added a few pointers.
Also note what Sarah posted

 

I see quite a few solder bridges, and that means that the soldering tip is too big. Also, too much solder has been used. I thik there were at least a total of six solder bridges, two in the very first row.

 

I see quite a few solder bridges, and that means that the soldering tip is too big. Also, too much solder has been used. I thik there were at least a total of six solder bridges, two in the very first row.

I also see many solder bridges and track shorts through partially cut track slivers shorting to the next track over. I always run a thin steel rule along every track after finishing a board to both remove the flux and detect shorts!