Vectronics VEC-1290K Manual - page 21

Only high-quality components and proven circuit designs are used i Vectronics

kits. In very rare instances is a defective component the source of problem.

Replacement of defective parts is covered in the Warranty section Ninety-five

percent of the kits returned for factory repair are due to solderin problems or

parts in the wrong locations. We advise repeating the assembl instructions step-

by-step, looking for mistakes or soldering problems. Be especially wary of

electrolytic capacitors and semiconductors. Kit builders often miss obvious

mistakes. What is needed is a "fresh" set of eyes. Enlist a friend to go over your

work.

Always check the obvious! Is the power supply plugged in? Is the power switch

on?

Low range: Check power supply voltage, alignment of C11 and proper jumper

configuration for antenna matching circuit. Check antenna wire connection at

ANTI on pc board. Antenna not located in an optimum location.

Audio distorted: Gain control set too high. Capacitor C11 improperly tuned, or

wrong jumper configuration for antenna matching circuit.

Loud hum on audio: Bad audio cables, check for broken shield wires. Power

supply filtering poor.

Osciilator dead: CMOS device U1 (4049A) defective.

Carrier signal, no audio: Bad audio cables, RI set to minimum. IC U2 (LM386)

defective.