Disconnect The External; Connector J140; Scale To Measure The Resistance To A Ground Pin; Ohms - IBM 5280 Manual

COMMUNICATIONS MAP
CBS COUPLER
PAGE 2 OF 13
(Step 001 continued)
switch on the base. Place the
Talk/Data Switch (if present on
the telephone base) to Talk
position.
Connect the CE meter leads TO
THE COUPLER as follows:
Plus to 'Si,gnal Ground' (gray)
Minus to 'Switch Hook' (red)
- A positive deflection indicates
a -EIA level.
Is 'Switch Hook', (red lead), at a
- EIA level?
Y N
002
Connect the CE meter leads TO
THE COUPLER as follows:
Minus to 'Signal Ground'
(gray)
Plus to 'Switch Hook' (red)
Is 'Switch Hook', (red lead), at
a +EIA level?
Y N
003
- Disconnect the external
machine at cable from the
connector J140.
Did 'Switch Hook' (red lead)
go to +EIA or -EIA level?
Y N
3 3
ABC
004
The
iIA
correct.
level ;s not
Have the customer place a
call to the telephone
company.
C MAP 3012-2
005
Power off.
Reinstall the external cable at
connector J140.
Remove the 3SLS line adapter
card.
- 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-D8BI0, 'Switch Hook', to
A-DSD08, 'Gnd' (MIM 867, probe
point C).
Is the line grounded?
Y N
006
007
Defective 38LS line adapter
card (A-D7)(MIM 812).
Remove the communications MPU
card (A-ES)(MIM 811)
Is the line still grounded?
Y N
008
Disconnect the internal cable
from the A-ES-JOI connector.
Use the CE meter on the RXl
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-l4 'Switch Hook', to
POl-23 ,'Signal Ground' (MIM
867, probe point E).
Is the line grounded?
Y N
EC840874 PEC839787
3 3 3
D E F MAP 3012-2