Scale Lamp Replacement
Scale Lamp Replacement While designed for the longest possible
service life, the incandesent lamps that illuminate the meter
scales may eventaully need to be replaced. Typical causes
of lamp failure include schock, excessive heat buildup within
the meter enclosure due to inadequate air circulation, line
voltage spikes, and long-term filament stress fatigue.
All current model Loudness Monitors use 6.3V lamps. Previous
monitors used 12, 10, and 8V lamps. To ensure the correct
replacement lamps are installed, it is strongly recommended
that the lamp voltage be first measured. To do this, the
meter must be removed from its case. On the LED display board,
locate the printed circuit trace strips that supply power
to the lamps (see illustration below) and measure the voltage
across the lamps (across the two copper-colored strips).
You may wish to indicate the lamp voltage on a self-adhesive
label placed on the meter's rear panel for future reference.