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Darkroom timer V2.0A project question ????? (Solved)


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Hi, this is my very first post on this forum, so I hope someone will kindly answer my question.

I'm building the Darkroom timer found on this site. I have made the circuit on my breadboard and everything works very well. So I'm making the first part, the display unit. Just for your information I make my own PCB.

That's where my problem is !!!! I'm loosing my mind here ....

Let say I have the number zero displayed on all 4 LEDS, the letter D, E don't light up on LED 1 but the other 3 LEDS are ok ???? Sometime letter C of LED 1 2 3 is barely visible but LED 4 is ok ???? That goes for other numbers too !!!!

And before you ask, none of the 7-segment of the LEDS are burned because I can switch the LED is any position, they are mounted on 20 pins dip socket that I cut.

Thanks for your answers.

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  • 4 weeks later...

Flux , except in extremely high impedance circuits like pH meter inputs, should not cause a problem.  Years ago I read in an H-P service bulletin concerning field repairs to PCBs, that unless "all" flux can be removed (think in-factory process) it should be left in place.


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