Philips PM3320 Operating Manual page 142

4-126E
4.5
45.1
4.5.2
4.5.3
The Power supply section
The power supply, which accepts most mains voltage ranges in use (90-264 Vac), produces the
various voltages which are used for the electronic circuits, the EHT voltage for the CRT inclusive.
Italso generates a mains voltage related LINE TRIGGER signal, which is fed to the EXTERNAL
TRIGGER INPUT circuit for line triggering.
BRIEF CHECKING PROCEDURE
General information
This procedure is intended to check the oscilloscope performance with a minimum of test steps
and actions required.
lt is assumed that the operator doing this test is familiar with oscilloscopes and their
characteristics.
WARNING: Before switching-on, ensure that the oscilloscope has been installed in
accordance with the instructions mentioned in Chapter 3.
NOTE: The procedure does not check every facet of the instrument's calibration; rather, itis
concerned primarily with those parts of the instrument that are essential to
measurement accuracy and correct operation.
Removing the instrument covers is not necessary to perform this procedure. All
checks are made from the outside of the instrument.
if this test is started a few minutes after switching-on, bear in mind that test steps may be out of
specification, due to insufficient warm-up time.
The check is set up in a logical sequence. The complete flow should be followed carefully to
prevent repeating all contro! settings and input signals at the start of every single check.
For a complete check of every facet of the instrument's calibration, refer to the section
"Performance Check" in the service manual! (for qualified persons only).
No additional test equipment is necessary apart from a 10:1 attenuator probe supplied with the
oscilloscope and an adaptor BNC female-probe tip (order nr. 5322 263 50022),
Preliminary settings
- Switch the oscilloscope on and check if the power-up routine is executed.
- Connect the CAL signal from the CAL output socket to the A input via the 10:1 att. probe with
automatic range adaption BNC plug.
- Press the green pushbutton AUTO; a square wave should become visible on the CRT screen.
- Set the two INTENS controls for the right intensities for trace and text.
- Adjust the FOCUS screwdriver control for a well defined sharp trace and text
- Set the ILLUM contro! for the right intensity of the grid illumination.
Trace rotation
~ Press pushbutton VERTICAL COUPLING.
- Press softkey GROUND channel A; a straight line should become visible on the screen.
- Setthe trace of channel A in the vertical mid-position of the screen by turning the Y-POSITION
control.
~ Check thatthe trace lies in parallel with the horizontal graticule lines; if necessary, readjust the
TRACE ROT screwdriver control.