DIGITAL MULTIMETER OPERATION

The brief device description

Multimeter is the universal measuring device, allowing to carry out measurement at alternating and direct current circuit and to determine some parameters of electric circuit elements.

The device builds into rectangular plastic case. A four-digit numeral indicator, a start button ("POWER") of the device, a switch of operating modes and measurement limits, a socket for installation of tested transistors, plugs for connection of measuring wires are disposed at the upper case panel.

Back case cover is removable. Behind it, except for a circuit board, there are device power supply and a safety fuse. The back cover has a niche at where the support is removed. With its help the device can get oblique position on a working table.

Device operation

Operating procedure: power up of the device, select of operating mode and measurement limit, connect to investigated circuit, carrying out of measurements (readout), power down. For direct current measurement the switch goes to the sector, marked by "V=" , for direct current - to the sector "А=", for alternating voltage - to the "V~", for alternating current - to the "А~". The switch sets opposite to one of the chosen sector figure.

Figures designate an upper bound of a measurement range. For example, the figure "2" in the sector, marked as "V=" means, that at switch setting opposite this figure it is possible to measure by the device the constant voltage which value lies in the range from 0 up to 2 V. Choosing a measurement limit, it is necessary to proceed with expected measurand value (it should be obviously less than an fixed measurement limit) and with necessary measurement accuracy or indications of the operating instruction. For example, at carrying out of measurements on a subcircuit where voltage value should make about 1.5 V, the device with the "2" fixed limit will measure this voltage value accurate within one thousand a volt, with the "20" limit - to within the 100-th share of a volt, with the "200" limit - up to one tenth.

For device connection to investigated circuit a special connecting wires, which inserted into relevant plugs on the front panel, are used. For example, for direct and alternative voltage measurement a plugs with "СОМ" and "V W", legends are used, for direct and alternative current strength measurement a connecting wires insert into the plugs, designated as "СОМ" and "MA".

Each measurement wire on the one side has the pin with a short tip, and a long tip on another one. The pin with a short tip inserts into device plugs. The wire ends with long insulating tips connected to a circuit points in which it is necessary to carry out measurements (according to the instruction for experiment and circuit).

Power up of the device happens by pressing the "POWER" button. Power down of the device carried out by repeated pressing of this button. It is not recommended for economy of the power supply resource to leave the device for a long downtime.

Possible malfunctions and their elimination

Device feed: a battery with 9V output voltage such as "Crone". It is necessary to replace device power supply at occurrence of the conventional sign on the relevant numeral indicator discharge warning. For this purpose the follow procedures make: to extract a support from a niche of the back case cover, to turn out a fixing screws and to remove a cover. After replacement of the battery these activities must be repeated in reverse order.

The power up device prepared for operation in a current strength measurement mode and connected to known good electric circuit, does not work. Thus on the indicator in the left bit position the "1" indicates irrespective of the fact which current measurement limit sets.

Malfunction caused by blowing of a safety fuse. Replacement of this fuse should be done as the replacement of the power supply. The new fuse should work at the current of 200 mA.