K2579 problem - LED problem

Kits Timers and Clocks
1

Hi

I hope someone can help, I had an old K2579 and have bought another kit and assembled it. But on the new one, the LED appeared not to be working and I’ve figured out why - when “started” the entire 12volts is going to the LED, unlike on the old one.

I’ve compared both and couldn’t see any difference what-so-ever, I’ve built it exactly the same - so bought another and guess what that LED has blown too, 12volts going to the second new kit.

The new kit (the first and second new kit) stops and starts fine, the only problem is the LED.

Can any cleaver member guess what might be up?

Thanks

2

Hi,

Is R7 a 1K resistor?
Is the polarity of the LED correct

This is just a guess.
But I hope it helps.

3

That was my first thought, but yes resistor is there (both boards ARE identical) and the +/- of the LED is correct.

Being honest I’m sure the LED did light up to begin with and it was only when it stopped lighting up did i check the voltage with a multimeter. The multimeter does confirm the ohms value too - if the resistor was faulty or whatever, I’m guessing the multimeter wouldn’t show 1k?

4

Is the relay engaging and disengaging.

If you look at the schematic there will always be 12 volts on the anode of the LED.

If the relay is working sounds like the LED itself maybe bad.