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(3) When it is conflnned that the receiver
RF input filter circuit CFL-184 andlor
itself is bad, replace the BK relay of the receiver,
R F A M P C A F - I 9 I .
6 . 3 . 2
N o s o u n d
The sound does not come through the speaker even though the speaker is connected to
the receiver correctly, and no defects have been found in the speaker and indications of the
receiver. In such a case, check the receiver in the following procedures.
Checking procedure
( I ) Rernove the E!!&TE
connector from the receiver.
If the sound colnes out through the speaker, -tsK is grounded somewhere in the BK line.
Check wirings of otherreceivers, transmitters and consoles to which -BK line is connected
in parallel.
(2) Lock-out check of the synthesizer
Take out the receiver liom the cabinet case or rack, and check LEDs from the top after
turning on the power. LEDs can be visually checked through the hole on the top cover
of the receiver. If LED are off, it is correct. But if LED light, the synthesizer is locked
out. But the following case is not abnormal condition: After changing the receiver
frequency, LED light until the synthesizer is locked.
6.3.3 Noise and beat
Even though changing the receiving frequency band, noise or beat sound comes through
the speaker. But that noise is evidently not external noise.
Especially, in case of small ship, many kinds of electronic equipments are concentrated
in the small room, so that the mutual interference may happen among equipments. In many
cases, the receiver suffers intert-erence. When the mutual interference arises, search the
surrounding for the source of noise. Especially, when mounting a new electronic equipment,
you must check whether the new equipment gives the noise interference to the receiver or
n o t .
Checking procedure
( I ) Investigation of the source of noise
At first, set the receiver to such a condition where the noise comes out through the
speaker. Turn ofT the power of the equipments other than the receiver successively. If
the noise stops when turning off the power of some equipment, it is considered that the
equipment is the source of the noise. Sometimes, the power supply itself may generate
the high frequetrcy noise, not the electronic erluipment. In such a case, use the other
power supply line.
(2) Investigation of the route of noise
After checking the noise source, the route of the noise must be investigated. The noise
routes are largely classified as shown in the figure.
* 2 t -
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