Home › Evil Mad Scientist Forums › Larson Scanner and Menorah › Love the Mega Menorah 9000! … but might have overheated mine? › Re: Love the Mega Menorah 9000! … but might have overheated mine?
January 3, 2017 at 7:20 pm #22757
The Mega Menorah 9000 should be able to be stay on indefinitely.
If something got hot, that sounds like something was genuinely amiss, and there are a few different things that might have gone wrong.
The buttons do have a specific orientation, but (1) they slip in easily the correct way and can only be forced in the wrong way through protracted wrangling that involves weird bending of the pins (2) they can’t sit flat against the board if they’re in the wrong orientation. Even if you did manage to get them in the wrong way, that alone would make the button nonfunctional, but it should not overheat or cause other trouble; the switch is protected by R1, which limits the current through the switch to a very modest 5 mA. Similarly, a short circuit within the switch should only be able to cause a maximum of 5 mA current. And, 5 mA at 5 V should limit that to 25 mW of power, which is not enough to get “very hot” on a component of that size.
My best guess is that there was (possibly, is still) at least one short circuit on the board. With power disconnected, use your multimeter to check all four pins of the switch, to see how it is connected. Test first on the other switch (“Night”), to see what a (likely) good switch should look like. Two of the pins on one side are electrically connected, as are the two pins on the opposite side. Then, when you press the button, all four pins should be connected together.
Check to see if the two buttons respond this way. Also, check to see if they appear to be connected as per the schematic. S2 should connect to Vcc with a button press, S1 should connect to GND with a button press. Also, and importantly, check that these lines are not connected to other lines that they shouldn’t be. Also check, for example, that neighboring pins of the IC are not connected, and that the ends of nearby components such as R1 and R2, are not connected.
Please let me know what you find.