Actron CP7665 Operations Instructions download pdf (Page 11)

11

Fig. 12

leads across diode and view

display.

Display will show one of three

things:

• A typical voltage drop of

around 0.7V.

• A voltage drop of 0 volts.

• A “1” will appear indicating the

multimeter is overranged.

7. Switch RED and BLACK test

leads and repeat Step 6.

8. Test Results

If the display showed:

• A voltage drop of 0 volts in

both directions, then the diode

is shorted and needs to be

replaced.

• A “1” appears in both direc-

tions, then the diode is an open

circuit and needs to be re-

placed.

• The diode is good if the dis-

play reads around 0.5V–0.7V

in one direction and a “1” ap-

pears in the other direction

indicating the multimeter is

overranged.

Testing Diodes

A diode is an electrical component

that allows current to only flow in one

direction. When a positive voltage,

generally greater than 0.7V, is ap-

plied to the anode of a diode, the

diode will turn on and allow current to

flow. If this same voltage is applied to

the cathode, the diode would remain

off and no current would flow. There-

fore, in order to test a diode, you must

check it in both directions (i.e. anode-

to-cathode, and cathode-to-anode).

Diodes are typically found in alterna-

tors on automobiles.

Performing Diode Test (see Fig. 12):

Anode

Cathode

Black

Red

1. Insert BLACK test lead into

COM test lead jack.

2. Insert RED test lead into

test lead jack.

3. Turn multimeter rotary switch

to

function.

4. Touch RED and BLACK test

leads together to test continu-

ity.

Check display – should reset to

0.00.

5. Disconnect one end of diode

from circuit.

Diode must be totally isolated

from circuit in order to test its

functionality.

6. Connect RED and BLACK test

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