Operating Hints; Adjustment Procedure - Hameg Instruments Hm 8040 Bedienungselemente

Operating hints
The triple power supply has three electrically isolated
supply voltages. This permits easy series connection of
all output voltages and connection in parallel of the two
adjustable 0-20V supply voltages. In case of series con-
nection the maximum output voltage increases to 45V
with a maximum current of 400mA.
In case of parallel connection of the two adjustable 0-
20V supply voltages the output current increases to
800mA max. with a same voltage adjustment range of
0-20V.
The HM 8040 module uses the supply voltages available
from the HM 8001 mainframe, so that it has a limited
max. output power. As the HM 8040 unit develops
much heat, when operated at full capacity, simultane-
ous operation of 2 modules of this type in one HM 8001
mainframe is only admissible, if the total power con-
sumption of both modules does not exceed 36VA.
It is absolutely necessary to provide good heat dissi-
pation or ventilation.
Functional test and alignment procedure
This test will permit you to check the functions of the
module at certain time intervals. To obtain the normal
operating temperature the instrument should be turned
on at least 60 minutes before starting the test or adjust-
ment.
However, a re-alignment should only be performed, if
the required measuring equipment or instruments of
the adequate accuracy are available.
The following instructions will allow you to correct any
deviation of the module from the specification. The spe-
cial alignment sequence should be strictly observed.
Before opening the set, you should carefully read the
Safety and Warranty informations on page M2 of these
operating instructions.
Measuring equipment required
HM 8011-3 Digital Multimeter
20MHz Oscilloscope, e.g. HM 203-6
Resistor 2k&22 1%
Functional test
1) Check of max. output voltage: 20.3-21.5V
2) Check of min. output voltage: 25mV (R, <10kQ})
3) Check of min. output current adjustment range:
<10mA (@)/43 ccw)
4) Check of max. output current: 400 - 440 mA (@y42)
fully cw)
5) Check of overload indicators: Setting as for 3) or 4).
When the output terminals are short circuited the ap-
propriate overload LED lights.
6) Check of residual ripple and noise at the output ter-
minals: max. ripple and noise <1mV for all output
currents up to 400 mA. Visuel check with oscillo-
scope at output terminals or with DVM.
Like 6) but max. allowable ripple and noise for fixed
+5V output voltage is 5 mV for all output currents up
to 500 mA.
Sy
M4 — 8040
8) Check of the accuracy of the fixed +5V : +0.25V for
all output currents <500 mA.
9) Internal DC resistance of the fixed +5V voltage:
max. change of output voltage should be <125 mV
for output current changes of up to 500 mA.
10) Internal DC resistance of the variable output volt-
ages: max. change of the output voltage should be
<4 mV for output current changes of up to 400 mA.
Adjustment procedure
A Check of the reference voltages: (7)/@)/4)/@3 max.,
Viet = 4.75 V-5.25 V. If Vier iS > 5.25 V or the max. out-
put voltage of the 0-20 V sources is > 21.5 V, resistor
R 159 (R 160) 68.1 KQ is necessary.
B Adjustment of the max. input voltage for the HM 8040.
Vin; 24.8 - 25.8 V. Typ. value for R 103/104 is 953 -
1470 Q.
(Depends on the resistance ot the PTCs R 101/102)
C Adjustment of display offset: @/d3 min. (ccw); ad-
just Ug; to 1V +10 mV by means of the controls @)
and 49. Load output terminals @) and @ each with a
resistor 2 KQ 1%. Check output voltages with DVM.
Depress (2) and @). Adjust display of HM 8040 to 1
mA each side by means of VR 101/102. When taking
away the load resistances the display of the HM 8040
should change between 000 and 001. If the display
shows 01 or —01 the adjustment should be carried
out once again.
D Accuracy of current readings: (8)/@)/@)@ fully cw.
Switch DVM to 2A range and connect it directly to the
output terminals of the HM 8040. Adjust the reading
on the display of the HM 8040 to the value read on
the DVM.
E Accuracy of voltage readings: Adjust the output volt-
age of the HM 8040 to 9.95 V 0.01 V. Check with
DVM. Adjust the display of the HM 8040 by means of
VR 105/106 that way that the display changes be-
tween 9.9 V and 10 V.
Subject to change without notice