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ADCP-75-214 • Issue 2 • September 2006
Page 15
© 2006, ADC Telecommunications, Inc.
4.3 Troubleshooting Flowchart (For Systems With Three-Port MHUs)
If directed by the flowchart, refer to the troubleshooting matrix in Section 4.4 or to the return
loss sweep guide in Section 4.5.
ANY
LIGHTS ON
THE PDU?
ALARM
led
MHU
led
START
NO
OFF
YES
OFF
OFF
RED
MHU
led
YELLOW
SOLID
GREEN
The red Alarm led should come on
when any MHU select dip switch
is pushed to the down position. If
the bias-t connection is not made.
• CHECK DC CONNECTIVITY
TO THE
• CHECK MHU PORT FOR 18VDC.
IF NOT PRESENT, REPLACE PDU.
• CHECK BIAS-T CABLE FOR
18VDC. IF NOT
PRESENT,
REPLACE BIAS-T CABLE.
• CHECK BIAS-T FOR 18VDC.
IF NOT
PRESENT, REPLACE BIAS-T.
• CHECK RESISTANCE OF
FEEDLINE.
- LO OHMS OR
SHORTED;
PROBLEM TOP SIDE.
- HI OHMS OR OPEN IS
NORMAL
BUT ALSO MAY INDICATE A
DISCONTINUITY.
• CHECK SUPPLY IS -56 to -20 VDC or +20 to +56 VDC.
The red lead is connected to the higher potential.
• CHECK SUPPLY FUSE/BREAKER IS OK. (5A RATING)
• CHECK DC CABLE AND CONNECTION.PROBLEM
The red Fail led should come on when any MHU
select dip switch is pushed to the down position. If
the bias-t connection is not made.
TTA ACTIVE
ONE
PATH
FAILING
PDU OR
CONNECTIVITY
PROBLEM
REFER TO TROUBLESHOOTING MATRIX
21401-A