Onwa KR-1338, Service Manual

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4. MAINTENANCE
4.1 Remarks on Replacement of Major Parts
Turn off the power before replacing any parts
Do not touch the magnetron while the radar is transmitting. Sufficient high voltage
exsts at the magnetron to cause death.
MAGENTRON
The magnetron emits a strong magnetic field. For this reason, remove wrist watch
before performing the replacement and use a non-magnetic screwdriver to dismount
the magnetron. The estimated life of the magnetron is 2000 hours, (including time
in stand-by), however actual life depends on usage.
1. Turn off the power.
2. Dismount the transceiver module.
3. Dismount and replace the magnetron.
4. When a new magnetron is fitted, allow at least 30 minute pre-heating under
ST-BY. Turn on the power and measure magnetron current . See Chapter 3 for he-
ater voltage rating and potentiometer to adjust.
5. Transmit on long range and measure magnetron current. See Chapter 3 for ma-
gnetron current rating and potentiometer to adjust.
6. Reset "TX Hours" and "On Hours" on INSTALLATION SETUP menu. See page
4-3 for how to access this menu.
MIC
The MIC can be replaced individually. No adjustment is necessary after replacement.
SPU Board
Write down settings of MAIN and INSTALLATION menus before replacing the
board. Then, after replacing the board, reenter settings. (Reason: Settings are stored
in the E PROM(U48) on the SPU board.)
IMPORTANT: After replacing the board, the factory menu setting must be
carried out properly, otherwise the MIC will be damaged.
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