14: Maintenance
PRC1099A-MS
14-17
14.6.2
Basic Board Fault Location
Table 14-3 on page 14-17 provides a basic guide for locating faulty boards
without the use of test equipment. These methods cannot detect all fault
conditions. If this approach is unsuccessful, replace the boards systematically
A preliminary check can indicate which boards are operational. For example,
the Synthesizer board is used in both receive and transmit modes. This means
that the Synthesizer board is not faulty if either the transmitter or receiver is
operational.
Before replacing any boards, check all cable connections carefully. A broken
wire or a loose connector can prevent the board from operating.
It is normally not necessary to make any adjustments or to realign the
transceiver after replacing a board.
For procedures on removing and replacing boards, refer to “Board Removal
and Replacement” on page 14-7.
Receiver Audio
Garbled
One of the stations is set to
the wrong frequency or out
of calibration.
Use
Tune
knob to retune receiver.
No communication:
Receiver and
Transmitter appear to
operate normally
Incorrect frequency.
Incorrect sideband.
Check displayed frequency.
Check
Mode
knob (USB normal).
Table 14-2 General Fault Location Chart (continued)
Symptom
Possible Fault
Action
Table 14-3 Fault Location Table
Board
Symptom/Action
Possible Problem/Solution
Preliminary Check
Check supply vo12, +8, and +5.
Measure R8; look for read of 8V.
Press PTT; relay K13 on Audio/Filter board should close.
Measure T8; look for read of 8V.
Audio/Filter
Board
Audio completely dead, squelch off, no
hiss or static, maximum audio gain.
Board or handset defective. Squelch
mode is active.
TX has no output except in CW mode.
Handset defective.
1650 kHz IF
board
Receiver operational.
Board should also be operating in transmit
mode.
Disconnect
RX Out
coax connector.
If noise level does not decrease, the board
is defective.
Mixer Board
Disconnect 1650 kHz coax connector
from 1650 kHz IF board.
If receiver noise level does not decrease,
board is defective.