Bussard light kit failure

belkin321 · Post by **belkin321** » Sun Apr 20, 2014 6:48 pm

Hello.
A problem here for the electronic wizards. I have a bussard LED kit that uses a 4017 and 555 IC chips. Left and right are separate PCBs. The right side stopped working such that it does not rotate, but the LEDs stay on. If I turn the power on and off fast, the LEDs appear to rotate as normal. If I just turn the power back on, the LEDs just light again, but don't rotate. Is this a bad 4017 or 555 chip? Thanks

chiver · Post by **chiver** » Sun Apr 20, 2014 7:33 pm

Either a short some where or the chip is faulty, when I acadently cook the chip in a tea light candle the LED stays on with no flicker

Ziz · Post by **Ziz** » Mon Apr 21, 2014 5:03 am

Battery or power supply? If battery, it's possible the two circuits together are at their upper limit of the battery's V and mA capacity and now that you've been testing it for a bit, the battery is starting to die and the circuits are sensitive to the slight drop in battery strength and can't pull enough power to operate properly

Try hooking up a wall wart and see if that gets things running again.

belkin321 · Post by **belkin321** » Mon Apr 21, 2014 1:59 pm

The spinners use a wall wart power supply. I have tested each spinner independently...the left one works fine, but the right one fails as described.

brt · Post by **brt** » Mon Apr 21, 2014 3:26 pm

Static electricity can toast a 4017. Perhaps this might be affecting it.

Mr. Engineer · Post by **Mr. Engineer** » Tue May 06, 2014 7:11 pm

The 555 generates the pulse required by the 4017 to 'spin' the LEDs.

If you have a meter, you can test the voltage at Pin 3 of the 555 timer. If the needle fluctuates, the 555 is working. The 4017 is a CMOS IC, which has a wide operating voltage but is very sensitive to electrostatic which actually kills it.

1. Look for any possible shorts too.
2. Try replacing the 4017 first and then the 555. Do remember the orientation of both chips.