Connector On The External - IBM 5280 Manual

U Z A
6 7 A
7
COMMUNICATIONS MAP
CBS COUPLER
PAGE
8 OF 13
056
Disconnect the external
cable from the machine at
connector J140.
- 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
P140
connector
ON
THE EXTERNAL
CABLE~ measure from P140-04
'Off Hook', to P140-21
,'Signal Ground' (MIM
867~
probe point F).
Is the line grounded?
Y N
057
Defective internal cable.
058
Defective external cable.
059
- Defective logic bOdrd.
060
Connect the CE meter leads TO
THE
COUPLER as follows:
Plus to 'Signal Ground' (gray>
Minus to 'Coupler Cut Through'
(brown)
A
positive deflection indicates
-ErA
signal.
While the call is being placed and
the coupler telephone is ringing,
is 'Coupler Cut Through? (brown
lead) at -EIA level?
Y N
9
A A
B C
A
C
MAP
3012-8
061
Disconnect the external cable
from the machine at connector
J140.
Did
'Coupler Cut Through'
lead) go to -EIA level?
Y N
062
(brown
The problem is in the coupler.
Have the customer place
a
call
to the telephone company.
063
Power off.
Reinstall the external cable at
connec·tor J140.
Remove the
38LS
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-DSD09, 'Coupler Cut
Throught~
to
A-DSD08~
7Gnd
1
probe point C).
Is the line grounded?
Y N
064
(jvjHi 867,
Defective 38lS line adapter
card (A-D7)(MIM 812).
065
Remove the communications MPU
card.
Is the line still grounded?
Y N
I
9 9
A A
D E
ECS40874
PEC839787
MAP 3012-8