Platinum Z5 CD, Manual

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888-2408-002 6-3
WARNING: Disconnect primary power prior to servicing.
Troubleshooting
6.2.2 Multiple PA Failures in a Foursome
If 2 PAs were to fail in a single group of four or Foursome, the resulting system
imbalance would result in a power foldback to one of the Worst Case conditions as
stated in the table above. Since a single PA failure in a foursome does not create a
severe imbalance, one of the PA modules with a bad PA should be taken out, turned
over and re-inserted, placing the bad PA in a different foursome until there is
sufficient time to replace the failed PA. For example, if PA amplifiers B1 and B2
have failed, pull out the A2/B2 PA module, turn it over and plug it back in so that
the bad PA is in position A2 instead of B2. There are still 2 failed PAs, B1 and A2,
but now each one is in a different foursome. This will restore balance to the system
and the transmitter will still be able to operate at near full power output by
automatically increasing the drive to the remaining PAs (via the APC voltage). For
more information on Foursomes refer to Section IV, Overall System Theory, under
the heading “8-Way Combiner”.
For quick reference, the foursome groupings are as follows:
See Figure 4-5 and Figure 4-6 on page 4-12.
•
A1, A2, A3 and A4 - Front, Z-Plane A
•
B1, B2, B3 and B4 - Front, Z-Plane B
•
A5, A6, A7 and A8 - Rear, Z-Plane A
•
B5, B6, B7 and B8 - Rear, Z-Plane B
Table 6-1 Transmitter Power vs. Failure Modes
Platinum Z5
Best Case Power Out Worst Case Power Out
1 PA Failed 100% 100%
2 PA Failed 100% 75%
1 Module Removed 95% 95%
2 Modules Removed 75% 40%
*1 Power Supply Failed 20% 20%
*1 PA Controller Failed 20% 20%
*Loss of a PA Controller or Power Supply represents an equivalent loss of 8
of the 16 PAs.