So, I finished the build of my IN-8-2 all-in-one clock and all seemed to be going well. Almost. I had it on and got the Wi-fi set up. I could get into the setting but couldn't change them. It wouldn't update from the time server.
Ok, not too bad so far. It gets worse. Today I try it again. It would not connect to the wi-fi at all. I leave it on for about an hour to see if it would eventually connect. When I checked on it everything was off and the 7805 in IC1 was very hot.
Uh,oh. It gets worse. After unplugging it and letting it (and myself) cool off, I plug it back in so I can probe around with my meter (like I have any idea what I'm looking for). I accidentally brushed one of the leads across the pins on SV1. Either VIN and ground or VIN and VCC. I'm not sure. Lights out except very dim backlight leds. The power indicator led stayed on.
Obviously I fried something but I'm hoping it is salvageable. Any ideas where to start?
Hi Dave, this stuff happens. Let's see what took a hit.
From the top:
1) Unsocket everything. All socketable components out (controller, optos and K155).
2) Test the 5V test point. If you still read 5V, we know that the 7805 is still working.
3) If you have 5V, let it run for a while and see if the 7805 gets hot.
4) Put the controller back in, but leave everything else off board.
5) Check the 5V again. Still got 5V? Does anything get hot?
6) If you get past this point (I don't think so) we can start putting the other components back on.
My best guess is that the controller has taken a hit. If you happened to brush VIN to VCC, we'll have given the controller and the K155 over voltage. The K155 might survive it, but the controller won't.
If on the other hand you shorted GND to VCC, the 7805 will have been shorted. However 7805s have internal short protection, and it should have survived.
Just to let you know what I am thinking: The 7805 should not get that hot under normal circumstances, but it might if you use a power supply that is unregulated or just unstable. It shouldn't usually get too hot to touch. 9V DC at 1A is the best supply for this clock.
It will dissipate more heat if you have very bright LED settings or something else is drawing current. It could have been a faulty ESP that caused it to get hot.
One step at a time.
I think the controller is probably up the spout, and we have to try and identify the other parts if we can that are candidates for replacement.