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 .