Hameg HM5014-2 Service Manual page 13

Enter the internal adjustment menu of the HM5014-2 by pres-
sing the keys "Intens" and "Focus" while switching on the ins-
trument. The time until the instrument emits a "beep" is about
10 seconds, then the 2 buttons can be released. Instead of the
standard screen display the adjustment "**menu**" display
will appear on the screen. The items
5dBADJ
TGL +1
TGL-10
OSCADJ
INTENS
FOCUS
TR-ROT
EEPNEW
appear on the screen, and to the left a cursor is shown. Items
can be elected by pressing the Center button for moving the
cursor upwards, and the Marker button for moving the cursor
downwards. Items are selected by pressing the Ref.-Level
button. The screen menu shown for each item is customized
for each adjustment operation. To leave the adjustment menu,
switch off the unit.
2.2.2 Check of CRT-XY Display adjustment
Select item „TR-ROT" in the internal adjustment menu as des-
cribed in section 2.2.1. A set of 6 lines will appear on the CRT,
forming a rectangle and a center cross. Also shown is a verti-
cal line 1.5 cm from the right vertical side line, which is 6 cm
large and has highlighted points at each end.
Figure 2-3: Adjustment menu on CRT
The outer 4 lines forming the rectangle must be aligned exactly
along the outer perimeter of the CRT graticule, while the center
cross must be aligned with the 2 main axis of the graticule. De-
viations of up to 0.75 mm are permissible for the center cross
and up to 1 mm for the rectangle.
2.2.3 Check of CRT-Z Display and Focus adjustment
Select item „TR-ROT" in the internal adjustment menu as des-
cribed in section 2.2.1. A set of 6 lines will appear on the CRT,
forming a rectangle and a center cross. Also shown is a verti-
cal line 1.5 cm from the right vertical side line, which is 6 cm
large and has highlighted points at each end.
This display must be without any extra points at any place in the
CRT area. Also the width of the horizontal and vertical center
lines should be equal to each other in the center area of the
CRT (astigmatism check).
Select item „INTENS" in the internal adjustment menu as de-
scribed in section 2.2.1. The same screen contents as above will
2 . P e r f o r m a n c e a n d F u n c t i o n a l T e s t s
appear. Observe the voltage reading shown on upper right part
of CRT. Adjust this value to 1.50 volts using the rotary encoder.
Then select item „FOCUS" in the internal adjustment menu
as described in section 2.2.1. Again, the screen contents will
be the same as described above. Adjust for best focus of the
center cross on CRT. Using the reduced intensity just chosen,
the focus will give a very precisely defi ned rendering of the 2
center cross lines.
Select item „INTENS" in the internal adjustment menu as
described in section 2.2.1. Use the rotary encoder to adjust
the intensity voltage value on the CRT to the maximum value
of 5.10 volts. Check that the 2 center cross lines still have
the same width and are not out of focus, equalling or being
a fraction less in width compared to the width of the outer
rectangle lines.
2.2.4 Check of Dot-Join adjustment
Select item „TR-ROT" in the internal adjustment menu as des-
cribed in section 2.2.1. A set of 6 lines will appear on the CRT,
forming a rectangle and a center cross. Also shown is a vertical
line 1.5 cm from the right vertical side line, which is 6 cm large
(see Fig. 2-3) and has highlighted points at each end.
The upper end point of the single vertical line is about half as
bright as the lower end point. Check that both points occupy
a small area only. The lower end point is in the form of a hori-
zontal line of about 1 millimetre of length.
Swith off the unit to leave the adjustment menu.
2.2.5 Check of TCXO and 3rd LO adjustment
The checking of TCXO (temperature compensated crystal oscil-
lator) frequency is extremely critical because it depends lar-
gely on the correct period of warmup with casing on the unit.
Incorrect temperature during checking will lead to possibly
incorrect values of TCXO frequency.
Set the HM5014-2 to the following:
RBW: 1 MHz
Center: 500 MHz
Span: Zero Span
Ref.-Level: -20dBm
ATT: 10 dB
(Max Hold, Average,Video fi lter, Marker and Tracking Ge-
nerator not activated)
Connect a 500 MHz, -30 dBm signal (unmodulated) to the RF
input of the HM5014-2, as shown in measurement setup 1. Un-
plug the SMB connector [CiC2] underneath the RFC board gently
with a pair of pliers [A6]. Then connect it via an adaptor [M6] and
a coaxial cable [M8] to the "A" input of the frequency counter, as
shown in measurement setup 2 (using option "B" connection of
the HM5014-2).
Figure 2-4: Illustration of CiC2 connector
13
Subject to change without notice