Panasonic KX-F900 Service Manual page 65

I KX-F900
Below graph show you the wave form that is observed when SRAM doesn't work. (BUS line at SRAM is intentionally
opened.) Please compare OK (under) to NG (upper). SRAMCS (pin 20 of IC3) signal is coming like clock.
In the case of this wave form SRAM access doesn't work. If soldering, conductance is no problem, we need to replace
SRAM (IO3).
CH 1 5V/div
CH2 5V/div
CH3 5V/div
CH4 5V/div
Wl 51_s/div
Length 1k
W2 51u,s/div
^ Length lk
_amp,ng Normal
20Msps
Marker 1
Tv t372_..0._
Marker 2
T v
AT -1364.90ps
1/_T
732.7 Hz
z_V -4.8 V
Time
Time__Base I
H1 W1
10.0Vi
Roll
Off
tTrigger _'CH1/2 zxMEM1AMEM2 Time/div
Wl
A0
SRAMCS
Time Base
External
NG
Like clock
-I
O
C
m
O
O
-4
Z
Q
Q
C
m
CH1 5V/div
CH2 5Vtdiv
CH3 5V/div
CH4 5V/diM
Wl 21_s/div
Length 400
W2 5tls/div
Length 1k
bamp,ng
Normal
20Msps
Marker 1
vT,37 :00.
Marker 2
V
AT -1364.90ps
l/AT
732.7 _z
AV 0.0
Time
Time__Base I
H1 W1
10.0V_ A0
DO
i : i
......................... , ...... : i i
ROMCS ............................ i................ i........
SRAMCS :: : i :
-4o.ov
1362.:40Fs 1382-:.40ps
;,I'1 I I L
Time/div
wt
Time Base
External
OK
q
65