Raymarine Apelco 5200 User Manual page 34

Item Number
CPU inoperative
7
Display malfunction
8
No transmit (TX)
9
Low RF power output
1 0
Poor or no modulation
1 1
PLL output frequency or level
incorrect
1 2
Symptom
a. Turn off the power once, and try again
b. Check CPU clock frequencies (pins 22 and 23, and
pins 26 and 27 of IC201)
c. If clock frequency is not present, check for
a. Check the interconnection to the LCD display
b. Inoperative CPU
a. Defective PlT switch
b. Defective regulators IC7(5V)
c. Defective Ql2(TX +B)
d. Check power transmit circuit @I ,Q2,and/or
e. Failure oflVC0 circuit (Q4 and /or Q3) or PLL IC3
f. Check PLL control voltage for 3.5 VDC at TPI on
channel 60.
g. Failure of talk detection circuit (IC201)
a. Check RF power output from ICl . If it checks
good, check the triple Pi type network components
(D4). If not good then check the voltage level
outputs of the drive amplifiers Qland Q2 as well as
the associated circuitry
Check
b.
a. Check,VCO
PLL phase detector output at pin 12 of PLL IC3 and
associated circuitry
b. Check 12.8 MHz crystal
a. Check frequency of 12.8 MHz crystal(XLT1)
b. Check the frequency input at pin 14 of IC3 and
Table 54 (Continued)
Possible Cause
power control circuit (Q24,Q9,QlO)
output frequency at pin 14 of PLL IC3
26
ICI)
and