Nellcor NPB-190 Service Manual page 80

VDD
L21 600R
+
C71
1.0U
20V
I237
U19
14 14
PWR D1
I97 D2
I98
4 4
TXD
T1IN T1LDR
5 T2LDR 6
NURSE-CALL
T2IN
I99
RXD 9 9
R1OUT R1DIN
12 12
I88 R2OUT R2DIN
TP26
8 8
EN
EXCOM-SHTDWN 1 1 GND 7
SHDN
I192
MAX250S
R72
10.0K
ISOLATION BARRIER
EIA-232 Port
035191
T2
SCHOTT 67129080
CLKDRV1 1 1 6 6
2 2
CLKDRV2
L22
3 3 4 4
600R
high power
C117 C89
clocks
3300P
3300P
50V
50V
C75
R74
2200P
4.02K
50V
L23
I238
8 8 TH
600R
6 6
2 2
3 5 5
7 7
U18
6N136
2 2
13 13
6
3 3 TXDLDR
6 DTRLDR
10 10 RXDIN
11 11
7
C76
U16
4N26
0.1U
VDD
R73
4.02K
U17
TH 8 8 6N136
6 6
2 2
5 5 3 3
7 7
+
C73
C72
1.0U 1.0U
+
20V
20V
TP29
CR12
1N914
3 3 1 1
TP31
U15
1 1 2 2 VPLUS
AC V+
DTR 3 3 13 13 VMINUS
T1DIN V-
TX 4 4
T2DIN
8 8
RTRI
I87
RXDLDR 5 5
R1LDR
6 9
R2LDR R2IN
I86
10 10 RXD232
R1IN
7 7
BYP
11 11
T2OUT
14 14 T1OUT 12 12
ISO_GND
MAX251S TXDOUT
+
C74
Z5U
4.7U
NCALOUT
35V IGND
TP24
I
R76
100M
1/4W
TH
E
VPLUS
CR11
SMCJ22C
22V
VMINUS
CR16 CR13 CR14 CR15
BAV99 BAV99 BAV99 BAV99
I
IGND
DT1
600V
TH
SH1 BD MTG HOLE
Isolation Barrier EIA-232 Port Schematic Diagram (5 of 10)
J2
16 16
1 1
9 9
2 2
10 10
3 3
11 11
4 4
12 12
5 5
13 13
6 6
14 14
7 7
15 15
8 8
17 17
CON_DB15F
Figure S-7
S-19