IBM 5110 Series Maintenance Analysis Procedures page 199

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Local CBS type coupler
(Auto Answer) MAP for 38LS
PAGE 1 OF 7
001
Use this MAP to isolate problems to the local
38LS integrated modem or local CBS type
coupler by using a nearby telephone.
- Verify that the connections from the modem to
the coupler are correct (see color code chart).
- Make DATA TERMINAL READY (DTR) inactive
by pressing the RESTART key.
- Select the 15 VDC range on the CE meter.
- The MAP will state which CE meter lead to
probe the signal to be measured. At that time,
connect the other lead to SG (SIGNAL
GROUND) if probing at the coupler or to C2D08
if probing on the C2 (38LS) card.
- Lift the modem telephone handset from the
cradle. DO NOT lift the exclusion key.
- Listen for the dial tone.
Do you hear the dial tone?
V N
002
- Lift the exclusion key.
Do you hear the dial tone now?
V N
003
Telephone problem.
Go to Page 4, Step 034, Entry Point A.
004
- Dial a nearby telephone.
Can calls be completed like an ordinary
telephone?
V N
005
Telephone problem.
Go to Page 4, Step 034, Entry Point A.
©
Copyright IBM Corp. 1979
4 2
***
COLOR CODE CHART
***
Switch Hook (SH)
=
Red
Signal Ground (SG) = Grey
MAP 0832-1
Data Modem Ready (DA)
=
Yellow
Coupler Cut Through (CCT)
=
Brown
Off Hook (OH)
=
Blue
Ring Indicate (RI)
=
Violet
Data Tip (DT)
=
White
Data Ring (DR)
=
Black
NOTE - The inactive level of all the above coupler
connections except DT and DR are - EIA levels
(-3 to - 25 VDC) when measured to SG.
01JAN79
EC 836600 PEC 835541
A B
MAP 0832-1