[SOLVED] Velleman MK152 Kit won't light properly

I assembled the MK152 Wheel of Fortune Kit but when I push the button a single LED lights up and turns off immediately upon release. If I push and hold the button, then the LEDs begin to light in sequence (clockwise), each LED illuminating for one second.

Somethings I've noticed about the assembly:

-IC2 was slightly out of its socket on one side. I pushed the chip fully into the socket but operation remained the same.

-IC2's socket is slightly raised on one side though all of the socket's pins appear to potrude though the PCB and make contact with the copper pad and the solder.

-I didn't use a heat sink when soldering. Could this have messed up the diode?


I took out the ICs to touch up the soldering work on the back of the PCB (some joints had parts of the copper pad still exposed). When trying to put IC1 back into place, I bent one of the pins (sorry, I can't remember which one). Using a pair of tweezers, I put the pin back into its correct shape and inserted IC1 into its socket. Upon restarting the device, it operated in the same manner as described in the first paragraph.

Here is a picture of the front of the kit:

DSC00543 | Flickr - Photo Sharing!

Here's the back:

DSC00541 | Flickr - Photo Sharing!



I'm not sure what to do next. I'm new to electronics in general and this is only my second kit. Any help is appreciated.

P.S.: This is my first time dealing with ICs and it took quite a bit of force to get them into their sockets. And as far as getting them out of the socket, I had to use the little flat head tool that came with my soldering iron to pry them out. Is that normal? I want to make sure I'm not messing up the chips by the way I'm handling them.

Thank You

I've compared your photographs to my working MK152 and all of your components look good except I can't tell if the electrolytic capacitors are in the correct locations. C2 should be 1µF and C3 should be 47µF. You should check that.

It's not likely that you damaged the diode. Your soldering is not too bad but most joints have too much solder on them and it looks like you had a little trouble getting the copper pads to wet. Try gently precleaning the copper with a little alcohol and a Scotch-Brite type nylon pad before you start on your next project. You could reflow the board with some flux and maybe wick away a little of the excess solder in some places. You also have some small flecks of solder adhered to flux on the board. Those should be cleaned off with a stiff brush (tooth brushes work) before you put the battery holder on as they can come loose and lodge between connections shorting them. Check out this excellent video on basic soldering: How and WHY to Solder Correctly - YouTube.

IC pins come with the leads splayed out and need to be straightened en masse a little before inserting them into a socket. Most of us accomplish this by pushing each row of dip leads against a hard flat surface carefully until they're perpendicular to the dip body and parallel to each other.

KJ6EAD,

Thanks for your suggestions. The electrolytic capacitors were indeed switched. After I did this, the LED lit up rapidly while the button was depressed. As soon as I released the button, however, the lights went out immediately (no deceleration). I then tried to desolder socket for IC2 and place it flush against the PCB with only limited success. However, after fiddling with the socket, it now takes three seconds for the LEDs to slow down and go out.

I found a YouTube video of the MK152 and the lights on that unit continued "spinning" for eight seconds after the button was released. Tomorrow I will pick up a desoldering braid and finally get the IC2 socket into place. Maybe that will lengthen the spin time.

Thanks again,
Bishop

Is there any chance that you now have one of the electrolytic capacitors in backwards?

Sorry, I forgot to update this thread. Yes, the capacitors were in backward. The unit now runs exactly as I have seen others on the internet. Thanks again.

Marking as solved