IBM 5280 Manual page 223

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X COMt'WN I CAT IONS
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CBS COUPLER
PAGE 7 OF 13
047
-
Disconnect the external
cable from the machine at
connector J140.
At the P140
r.onnpr.tor
ON TH~
EXTERNAL CABLE check
continuity between P140-04
'+Off Hook' (MIM 867, probe
point F) and the Blue lead
AT THE COUPLER.
Is continuity good?
Y N
048
- Defective external cable.
049
Defective internal cable.
OSO
- Defective communications MPU
card(A-ES)(MIM 811).
If a 'Ros Patch' cable is
connected to the card,
GO TO MAP 0600, ENTRY POINT A.
051
Use the CE meter on the RXI
scale to measure the resistance
to a ground pin. A short will
read less than 20 ohms. Measure
A-D8B03, 'Off HOOK', to A-D8D08,
'Gnd' (MIM 867, probe point C).
Is the line grounded?
Y N
Y
OS2
Defective 3SLS line adapter
card (A-D7)(MIM 812).
y
MAP 3012-7
053
Remove the communications MPU
card (A-E5)(MIM 811)
Is thp
lin~ ground~d?
Y N
054
- Disconnect the internal cable
from the A-ES-JOI connector.
- Use the CE meter on the RXI
scale to measure the
resistance to a ground pin. A
short will read less than 20
ohms. At the POI connector
ON
THE INTERNAL CABLE, measure
from POl-17 'Off Hook',
POI-23 ,'Signal Ground'
867, probe point E).
to
( Mlt-1
Is the line grounded?
Y N
S
S A
Z A
055
Defective communications MPU
card (A-ES)(MIM 811).
If a 'Ros Patch' cable is
connected to the card,
GO TO
MAP 0600,
ENTRY POINT A.
ECS40S74 PEC839787
MAP 3012-7