PK-232 TECHNICAL MANUAL
CHAPTER 7 – TROUBLESHOOTING
PK232TM Rev. A 5/87
7-1
Page 40
CHAPTER 7 – TROUBLESHOOTING
7.1.
Introduction
WARNING!
Never remove or insert an integrated circuit with power on!
The AEA PK-232 is a complex piece of electronic equipment. Servicing must be performed in
a logical manner. Prepare for troubleshooting by studying the circuit description in Chapter 3
and the circuit diagrams in APPENDIX C.
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.
7.2.
General Tests
In most cases, careful visual inspection combined with simple measurments 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 certain tests can be done without the aid of an oscilloscope, it will be required to
verify signals at various points on the board if the problem cannot be located by visual
means or with a meter.
Avoid short-circuiting on integrated circuits when connecting meter or oscilloscope probes to
the board. It is good parctice 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 on the threads of the screws that mount RS-232 I/O
connector at the rear of the printed-circuit board.
7.2.1.
Power Supply
Verfiy the poer supply fpr correct operation. Verify power supply levels at the outputs of
voltage regulators U21 and U41. as well as the output of U28.
o
Are the 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 regulaor and associated components, workin bachwards toward the
input power source.
o
If the voltage is low in conjunction with a hot regulator, suspect a short circuit on
the board.
Summary of Contents for PAKRATT PK-232
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