Vectronics VEC-1500K - Manual (Page 65)

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Operating Instructions
Connect a fresh battery, and turn the power switch on. The LEDs should
immediately begin flashing in sequence.
The “Blinky Light” project was designed especially for this Vectronics soldering
course. Sit back and enjoy the array of blinking lights! You have successfully
completed your project board.
Note: Changing the value of R2 will change the cycle rate of the
flashing LEDs.
In Case of Difficulty
Only high-quality components and proven circuit designs are used in Vectronics
kits. In very rare instances is a defective component the source of a problem.
Ninety-five percent of the kits returned for factory repair are due to soldering
problems or parts in the wrong locations. We advise repeating the assembly
instructions step-by-step, looking for mistakes or soldering problems. Be
especially wary of electrolytic capacitors and semiconductors. Kit builders often
miss obvious mistakes. Sometimes what is needed is a “fresh” set of eyes. You
may want to enlist a friend to go over your work.
Always check the obvious! Is the battery dead? Is the power switch on?
Connect a fresh battery and turn the power switch on (“ON” is indicated by the
switch remaining in the inward position).
Using a voltmeter, nine volts should be present on pins 4 and 8 of U1, and on pin
16 of U2. Use a DC coupled oscilloscope (5-V per division) and check pin 3 of
U1 for a pulse train.
1. All LEDs flashing, but not in proper sequence: Check jumper wiring.
2. Some LEDs not lighting: Check jumper wiring. Check LEDs for proper
orientation on PC board. Driver transistor installed wrong.
3. LEDs dim, erratic operation: Check battery voltage.