Service manual

Wells-Garnder Color Vector Monitor Guide
Page 62 of 73
combinations should show a resistance and that value should be 2.5K Ohms; none of the
resistances should be 0 Ohms (shorted).
TESTING TRANSISTORS WITH A DIGITAL MULTI-METER
Set your meter to the diode test. Connect the red meter lead to the base of the transistor. Connect
the black meter lead to the emitter. A good NPN transistor will read a JUNCTION DROP
voltage of between 0.45v and 0.9v. A good PNP transistor will read OPEN. Leave the red meter
lead on the base and move the black lead to the collector. The reading should be the same as the
previous test. Reverse the meter leads in your hands and repeat the test. This time, connect the
black meter lead to the base of the transistor. Connect the red meter lead to the emitter. A good
PNP transistor will read a JUNCTION DROP voltage of between 0.45v and 0.9v. A good NPN
transistor will read OPEN. Leave the black meter lead on the base and move the red lead to the
collector. The reading should be the same as the previous test. Place one meter lead on the
collector, the other on the emitter. The meter should read OPEN. Reverse your meter leads. The
meter should read OPEN. This is the same for both NPN and PNP transistors. Thanks to Randy
Fromm <[e-mail]> for this excellent summary of the diode test method.