39
Subject to change without notice
Adjustment Procedere HM303-6
WARNING
The Instrument must be disconnected from the mains power supply
whenever you open the case, repair or exchange parts.
For measurement and adjustment purposes or whenever the in-
strument is operated with removed case, the instrument must be
operated via an isolation transformer (Safety Class II).
HIGH VOLTAGE WARNING!
Hazardous High Voltage of up to –2000 Volts is present inside this
Instrument. The areas particularly affected by High Voltage are the
high voltage circuit on the PS board and the CT-board.
Mains (line) voltage is present at all parts and ground connections
at the primary side of the switch mode power supply.
SERVICE AND ADJUSTMENT
– of this instrument should only be performed in accordance
and in conjunction with the operating manual and the WAR-
NINGS contained therein, particularly Section “General
information” page 6 and 7.
– should only be performed by suitable qualifi ed and expe-
rienced service personnel, or should be referred to one
of the HAMEG companies listed on the rear cover of the
manual.
Test Instruments required:
1) Hameg Test Generator HZ620
or alternatively: Scope Tester HZ 60,
Amplitude Calibrator with 1 kHz square wave output, 600 Ω
impedance, rise time faster than 150 ns. Output voltage
2 mV – 20 Volts in 1-2-5 sequence for 4 divisions of display
amplitude and Time Mark Generator from 0.1 μs/div to
0.5 s/div. Output min. 10 mV into 50 Ω.
2) Programmable Synthesizer HM813x
or alternatively
Constant Amplitude Sine Wave Generator, 20 Hz – 250 MHz,
output 5 mV
pp
– 5 V
pp
into 50 Ωs (e.g. HM 813x, TEK SG502
+ TEK SG503).
3) Pre-attenuator 2:1 (1 MΩ II 12-48pF), e.g. HZ 23.
4) 50Ω BNC through-Termination, e.g. HZ22.
5) 2 BNC-cables, 50 Ωs, e.g. HZ34.
6) BNC
T-Connector.
7) Oscilloscope Probe 10:1, with exactly 9 MΩ series resistance
and compensated for test-oscilloscope mentioned under
8).
8) Oscilloscope 100MHz, 5 mV/div to 5 V/div, e.g. HM 1000.
9) Trimming/adjusting tool.
10) Variable output safety Isolation Transformer (Safety Class
II).
11) Video Signal Generator with positive and negative signal
output.
12) Metal sheet for cabinet capacity simulation during Y fi nal
amplifi er adjustment.
13) Digital Multimeter, e.g. HM8011.
This procedure covers all adjustments and the most important
– but not all – performance checks. The correct sequence of all
adjustment steps must be strictly followed.
Exact adjustment is only possible when any infl uence of the Earth`s
magnetic fi eld has been compensated for with the trimmer marked
TR (trace rotation) on the front panel.
All adjustments should only be performed by qualified and ex-
perienced personnel. This is particularly important for adjustments
in the high voltage section of the instrument.
A d j u s t m e n t P r o c e d e r e H M 3 0 3 - 6
