I notice the LED's are hooked up direct to 12 volts. You can't do that. It will burn the LED's up. Place a 330 ohm resistor in series with each LED to lower the current draw down.
Daniel Dillon Seminole, Ok.
Actually, for a nominal 12V system (which is usually in the 12.6-14.0V range), 330 is way too low for an LED, you'll be running 30mA through it and that's too much.
Use something in the 560-820 ohm range, and you should be ok, BUT (and this is a big but), you need to make sure your resistor is rated properly. For 560 ohm on such a system, it will dissipate about 1/4W, and you want to derate the resistor by about 4, so you would need a 1 watt resistor. If you want to work it backwards, you could use a 1/2W resistor, which would derate to 1/8W, and assuming 12V (max) across the resistor, you would something around 1150 ohms (so something like a 1.0K or 1.2K would be fine, too). This will provide only about 10mA of current to the LED, which is VISIBLE, but not horribly bright unless you're using a high-efficiency LED.
Bottom line, you have to look at all of the parameters of what you have for your components.
David Erbas-White
As mentioned by other posters, the LED's cannot be hooked to a voltage source without current limiters. Following the links you provided shows the initial design uses current limited LED's (built-in resistors). If you used those type LED's, there shouldn't be a problem. The fact you got the LED's to work again a week later shows they are not destroyed and are probably the correct types.
Nothing in the design indicates any time dependent failures (no thermal resets, etc).
Note that Relay 5 contacts provide the current path for the remote continuity indicator LED. The pad box continuity button provides current for buzzer 2 (through the ignitors) AND to the coil of relay 5; the buzzer and the relay coil are in paralell. If the continuity test works at the pad (buzzer 2 sounds) but the LED does not light, we are not energizing relay 5. The current through this path may be marginal and insufficient to RELIABLY pull in relay 5. Try a test with the ignitor leads shorted as close to the pad box as possible and see if you get the LED to light. If you can remove a lead from buzzer 2, do so and try another continuity test at the pad and see if relay 5 energizes (LED lights). There may be a current shunt issue (voltage drop across paralell devices) between the buzzer and the coil of relay 5. Marginal currents may cause erratic problems that look like something else.
This assumes there are no wiring errors.
Hope this helps.
Could be a polarity problem. A full wave bridge rec would prevent it. Gary Deaver
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