PK-88 OPERATING MANUAL
TROUBLESHOOTING
6 - 1
PK-88 - 143
CHAPTER 6 – TROUBLESHOOTING
6.1.
Introduction
WARNING !!
NEVER REMOVE OR INSERT AN INTEGRATED CIRCUIT DEVICE
WITH POWER APPLIED
The AEA PK-88 is a complex piece of electronic equipment. Servicing must be performed in
a logical manner. Prepare for troubleshooting by studying the circuit diagram in the appendi-
ces.
Although it is not possible to present all possible problems, symptoms and probable solu-
tions, this section offers general troubleshooting directions based on our experience.
6.2.
General Tests
In most cases, careful visual inspection combined with simple measurements usually reveals
the problem.
The single most-useful tool for troubleshooting is a digital voltmeter (DVM) for reading AC
and DC voltages, one that permits non-destructive resistance measurements while the inte-
grated circuits are still in their sockets.
Although some tests can be done without the aid of an oscilloscope, certain signals must be
verified at various points on the board if the problem cannot be located by visual means or
with a meter.
Avoid short-circuiting pins on integrated circuits when connecting meter or oscilloscope
probes to the board. It is good practice to attach a secure ground wire to the meter or oscil-
loscope, some point that cannot accidentally short-circuit components on the board.
A good point to pick up this ground is pin 1 of the Radio connector J2.
6.2.1.
Power Supply
Verify Fuse F1. If the fuse is intact, then verify the power supply for correct operation.
Verify power supply levels at the outputs of voltage regulators IC1 and DC-to-DC convert-
er IC3.
o
Are the voltages close to their nominal values?
o
Do all the integrated circuits in the suspected area have the proper voltage on their
power pins?
o
Is there excessive ripple in any of the DC voltage lines?
o
If so, verify the regulator and associated components, working backwards toward
the input power source.
o
If the voltage is low in conjunction with a hot regulator, suspect a short circuit on
the board, or defective (hot) integrated circuit.
