I purchased and assembled two of these kits at the same time. Both seem to have the same problem: when a contestant button is pushed (to “ring in”), both the corresponding contestant LED and the quizmaster LED light up, but don’t stay lit - they go off as soon as I release the button. If I push the quizmaster button while holding one of the contestant buttons, both LEDs will go out momentarily but light up again as soon as I release the quizmaster button.
I’ve double checked the values and polarities of all components, and I can’t see any problems with the soldering job. Any suggestions??
I have built many of these kits and the only time I have had this problem is with a mistake in the assembly - often a diode the wrong way round, and once a transisto in backwards!