40-A2, 20-A2, and 10-A2 Internal Fuse Replacement

The model 40-A2, 20-A2, and 10-A2 Loudness Monitors are protected by an internal fuse, which is soldered in the power supply section of the main circuit board. On rare occassions, this fuse can fail as a result of power line spikes or transients, resulting in a totally dead meter. If you experience this symptom, check the fuse for contintuity (assuming normal line voltage is being supplied to the meter). CAUTION: Be sure the meter is unplugged from the mains supply before performing this check.

To gain access to the pico-fuse, the meter case must be removed. Locate fuse F76 on the main circuit board it looks similar to a small black resistor (highlighted area in the illustrations below).

Check the fuse for continuity. If open, replace with a 1.5/2.0A pico fuse. Power the meter up before reassembling to ensure no further problem exists .

The fuse (F-76) on the 40-A2 is located in the upper right quadrant of the circuit board, as highlighted below.
The fuse (F-76) on the 20-A2 is located in the lower left quadrant of the circuit board, as highlighted below.
The fuse (F-76) on the 10-A2 is located near the lower left corner of the circuit board, as highlighted below.


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: dorroughel@aol.com