Realistic TRC-449 - PLL Circuit Troubleshooting Guide

6. PLL CIRCUIT TROUBLESHOOTING HINTS
.-- ________ N_0----l Check whether there is R F
voltage on TP8.
Yes
Check whether there is ap-
prox. 2.2 Volt reading on
Yes
TP7.
Defective D44,
L 16 open
or
poor soldering
Defective I C5,
L
17 open or
poor soldering
Defective Crystal,
Switching
Circuit, or
TR34, 38 or 39 open or
poor soldering
Defective I C6
and/or 5V line.
Yes
Defective TR40 or
L24 or poor
soldering
Yes
Defective X tal5
and/or I C7 or
poor soldering.
Defective
FET4
L 19 open.
Yes
Yes
Check whether BCD
progr<lms on Pin 13 thru
21 of IC7 work as
specified in the Chart.
Defecti
ve
Switch.
Defective
Flexible
PCB
Yes
Defective TR30 and/or
31 or poor soldering
-19 -
Yes
Defective Pin
2, 3
or 4 of IC7 or
defective TR35 or
poor soldering
Re-align
L17
Defective IC7
Good
PLL is not
defective