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PK-88 OPERATING MANUAL
6.1
Introduction
NEVER REMOVE OR INSERT AN INTEGRATED CIRCUIT DEVICE
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 appendices.
Although it is not possible to present all possible problems, symptoms and
probable solutions, 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 integrated 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 oscilloscope, some point that cannot accidentally
short-circuit components on the board.
A good point to pick up this ground is pin-l of the Radio connector J2.
6.2.1
Power Supply
Verify Fuse Fl. 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 converter IC3.
Are the voltages close to their nominal values?
Do all the integrated circuits in the suspected area have the
proper voltage on their power pins?
Is there excessive ripple in any of the DC voltage lines?
If so, verify the regulator and associated components, working
backwards toward the input power source.
If the voltage is low in conjunction with a hot regulator, sus
pect a short circuit on the board, or defective (hot) integrated
circuit.
TROUBLESHOOTING
CHAPTER 6
TROUBLESHOOTING
WARNING !!
WITH POWER APPLIED
6-1
PK88-175
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