1
\$\begingroup\$

I have this old homemade digital clock which i'm trying to revive. It has sentimental value as it was built by my dad in his youth.

The problem is 2 of the segments only sometimes light up on the third module. There is no part number visible.

It doesn't look like it's a bad connection, i've resoldered most the wires that go to that module and as i've said, it occasionally works out of the blue..

I'm not sure where to begin investigating. I understand what most components do, but i'm a newby in electrical engineering. Any help appreciated.

My next idea is to start replacing components.. but i'm not sure how to check for bad components on the board.

I added the boost module in order to power it from 5v instead of 220v mains. The output is set to 15v as that was the value written on the board.

enter image description here

enter image description here

enter image description here

\$\endgroup\$
  • 1
    \$\begingroup\$ You might get lucky and find it's as simple as dry solder joints on the relevant segments; simply reflowing them with a soldering iron may fix it. Can you see the right voltages on the display pins? \$\endgroup\$ – Brian Drummond Oct 11 at 15:47
  • \$\begingroup\$ I'm not sure what i should see on the display pins.. the voltages are between 2.5v and 5v but i can't tell which is pins are common. \$\endgroup\$ – gedorin Oct 11 at 16:28
1
\$\begingroup\$

It's very Soviet looking. Those large LED displays were frequently made with series LED dice so if there is an open connection the whole segment will go out. If the display digit or display is potted there's not a heck of a lot you can do other than replace the entire bad part.

Maybe swap the MS digit? You might be able to rotate it 180° to get working segments but the connections won't likely be exactly mirror images.

| improve this answer | |
\$\endgroup\$
  • 1
    \$\begingroup\$ It is probably soviet. It was made in Romania in the communist period so all parts are most likely made in the USSR. Switching won't work as the 2 segments are on both sides, but i'm suspecting other components as the affected segments sometimes work. \$\endgroup\$ – gedorin Oct 11 at 15:40

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.