7-28
CORRECTIVE MAINTENANCE
7.1.7 Analog
A2
PCB
Troubleshooting.
7. 1.7.1 Test point signals.
The
analog A2 PCB is provided with test points, marked: TP" See figure 10.4: A2 PCB layout (wired
components side). These can be used to check correct functioning of the PCB.
AH measurements are made in the default MASTER RESET condition (start the measurements in the
ScopeMeter
using MASTER RESET).
A MASTER RESET is performed
as
follows:
1 , Rem0ve al I signals f
rom th e Scope
Meter,
2. Power the ScopeMeter with the Power Adaptsr/Battery charger PM8907.
3. Turn
off
the ScopeMeter
4,
Hold down the LCD key arvi press the ON/OFP key simultaneously. Two beeps are audible, and
all volatile memories {RAM with battery backup) are reset. The ScopeMeter is automatically set
to the meter mode.
NOTE: For the measurements on Test Points
W1...529 and 901... 921 apptya W kHz square wave
sigr\al to the channel
A BNC.
Press
the SCOPE button to go to SCOPE mode and press
AUTOSET to get
a
stable picture on the
LCD.
NOTE: For the measurements on Test Points 700...
906
first switch
on the ScopeMeter
using
a
MASTER
RESET Then press the SPEC/AL FUNCT/on key and the GENERATE softkey.
Use
the
select/adjust keys to select ^square 1.95 kHz'', and press the right most ENTER
softkey to aciiyete the generator.
Use
another osti I
loscope
with
high input
impedance
and 10:1 probe to
measure
the signals on the
lest points. See table 7.7:
Table 7.7 Oyen/iew signals on Test Points (TP) on analog A2 PCB.
Logic 0=0V, Logic 1=+5V
TP
Name Scope Freq. Data Description
101
0
102
0
103
[
^
0
1 «6
104
0
r
•••0
106
0
I
133
107 ATTB-A
[
0
108
0
i
-1B*w
109
POS-CHB
I
0
0
Base V2112
Output D2101
Output N2101
Collector V21 05
Base
V2104
Coliector V2111
TP for OFFSET DAC
POS-CHB
201 0 Base V2212
To Next Page
Loading...
