(e. g. in case of LEDs), or it is interrupted, connected in
reverse direction (reverse the polarity of the diode), or not
connected.
4.6 Transistor checking
(Except for DMT-1020)
Choose the hFE position at the rotary switch and plug the
transistor into the left or right half of the transistor jack
according to type (NPN or PNP) while watching its connec-
tion sequence. The current gain HFE up to 1000 is dis-
played.
The measuring conditions for this are collector / emittor
voltage = 2.8 V and basic current = 10 µA.
4.7 Test signal transmitter
Choose the position
at the rotary switch. Now at the test
tips an AC voltage signal which is very rich of harmonics of
approx. 50 Hz (DMT-1030) resp. approx. 1000 Hz (DMT-
1020) is available for measuring purposes. This signal is
overlapped by a DC voltage part so that the use of a cou-
pling capacitor is recommended.
For simple repairs this test signal can be placed e. g. at
the input of radios or amplifiers, and the signal can be
traced from step to step with an HF or LF millivoltmeter.
4.8 Battery and fuse replacement
If the battery is exhausted,
BAT
is displayed. To replace the
battery, open the housing (see also chapter 3), and the
exhausted 9 V transistor battery is replaced by a new one
while watching the correct polarity.
If a fuse is burnt, it is replaced by opening the housing
according to the battery replacement. The defective fuse is
to be replaced by a fuse 250 mA / 250 V, quick acting.
GB
18
Summary of Contents for DMT-1020
Page 2: ......
