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.

The follow lists the replacement lamp types for all Dorrough products. These lamps may be available at most electronics parts distributors.
Lamp Voltage
6.3 V
Mini-wheat T-1, size. Solder leads.
Used in all Dorrough products manufactured from Feburary 10, 1998
8 V
* JKL part number.
Phone 1.800.421.7244 or 1.818.896.0019 in California.
10 V
12 V


Dorrough produces a variety of digital audio meters, video meters, surround sound meters, and audio and video test products.
One year warranty is standard on all Dorrough products.
The company is located at 5221 Collier Place, Woodland Hills, California 91364 • Telephone (818) 998-2824. Fax: (818) 998-1507. Email: