Hameg HM 203, Руководство пользователя

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ADJUSTING ADVICES HM 2 0 3 -4
(see Adjusting Plan on page A1)
Check of the Unblanking Pulse on ChP 10
Pulse amplitude 22Vpp ± 5 % added with —1 900V (Caution!).
Check with
test oscilloscope
by means of a
1 0 X p ro b e with 10n F 2 k V
capacitor b etw een ChP 10 and probe input tip.
H M 2 03 -4 settings: Input coupling to GD (no input signal), 50^s/cm, int. Auto triggering
(free running).
Test scope settings: IV /c m (DC), 0.1 ms /c m , internal autom atic triggering.
Display on test scope:
Negative pulse tops exactly horizontal (forward sweep = bright trace on HM203-4).
Positive pulse tops approx, horizontal (fly back = blanked trace).
Readjustment of VR 3104
Adjust the forward current of the optocoupler diode in the middle of the following points:
a) bright spot on left side of the trace (screen of the HM 203-4),
b) shortening on right side of the trace (screen of the HM 203-4).
Between these two points is a wide range (needed for int. temperature variation). With cor­
rect adjustment, the edges of the square-wave should not be visible on the test scope.
Then change both
TIMEBASE settings to 0.5/ts/cm (HM 203-4) and 1/us/cm (test scope).
Now steep square-wave edges must be visible on the test scope screen.
Unblanking pulse on ChP 10
(triggering: free run),
seen on test oscilloscope.
a) incorrect b) incorrect c) correct
Baseline on HM 203-4 screen:
Sequence for important adjustments
Balance C H .I: Ad|. VR100 (see page M3).
Adj. VR103 using INVERT I button (see page T 1 ).
Balance CH.H:
Adj. VR 150 (see page M3).
Adj. V R 153 using Y-POS. II control (see page T 1).
Gain CH.H: Normally, VR151 is adj. If not, 20mVpp
1 kHz sq.-wv. to CH.II input, DC, depress C H .I/II button.
Check preamp, output on EY21 (PII-2/1 -1 ) with test scope
via 10X probe. Adj.
VR151 for approx. 360mVpp on EY21 .
Then adj. VR212 for a display of 4cm on HM 203-4 screen.
X g a in tCH.H): Set AC input coupling, release all buttons
in the Y-section, depress HOR. EXT. button with same
input signal. Two points are visible in the horizontal axis.
Adj VR222 for 4cm spacing.
Gain C H .I: If necessary, adj. VR101 (in same way as CH. II)
for approx. 360mVpp on EY1 1 (P1-2/1 -1 ).
Then adj.
VR202 for 4cm display height on HM 203-4 screen.
Autom atic Triggering: Set CH.I attenuator to lO m V/cm ,
input 30m V 50kHz sine (3cm display height).
Set attenuator to 0.1 V/cm (3mm display height).
Adj. VR352 (AT/NORM. button out) for just triggering.
Attenuator to 0.2V/cm : No triggering must be possible.
Depress + / — button, attenuator to 0.1 V/cm,
adj VR351 for same trigger threshold.
Repeat triggering adjustments.
Norm al Triggering: Depress AT/NORM. button, adj. LEVEL control
Check normal trigger mode using LEVEL control
with + / — button depressed and released.
Check triggering at 20MHz in same way.
D C triggering:
TRIGGER SELECTOR to AC, depress AT/NORM. button,
CH.I with DC input coupling, input signal 50kHz sine 3mm display height
(see above Automatic Triggering), adj. LEVEL control.
Then TRIGGER SELECTOR to DC, adj. VR221.
Repeat this adj. sequence for CH.II, adj. VR220
X -Y sensitivity:
Depress CH. I/II-TRIG. I/II button,
set CH.II input coupl. to AC, attenuator to 5mV/cm,
apply 50kHz sine for 6cm display height.
Depress DUAL, ALT/CHOP, X-Y buttons
Now display shows a horizontal and a crossing sloping line.
Adj.
X-POS. and Y-POS. I and II controls so that
the horizontal and the sloping line are centered.
Length of horizontal line and (projected) height of
sloping line should be 6cm. The point of intersection
should be approx, in center of graticule.
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