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6.2.2
Obvious Problems
Look for any unusual physical symptoms,
Are any components discolored?
Does something smell burned?
Do any of the parts seems excessively warm?
6.2.3
Assembly Problems
Carefully inspect the PC board and component installation.
Are all the socketed ICs firmly seated in their sockets?
Are any IC leads folded under the chip or bent so that they
aren't making proper contact with the integrated circuit socket?
6.2.4
Cabling Problems
Inspect the interconnection cabling. Where possible, substitute a spare PK-88
or other compatible TNC and attempt normal operation.
Do the cables perform correctly with another controller?
Has the radio and/or terminal been successfully used with this or
another controller?
Are all the connections tight?
Does the cable appear frayed or broken?
6.3
Specific Symptoms
Although the above steps may seem obvious, careful visual inspection often
points to a problem or provides significant indications as to the PK-88's most
suspect area.
Proceed to more specific analysis after completing the physical inspection and
dealing with the apparent problems.
6.3.1
Symptom: PK-88 appears dead
If no LEDS are lit at startup or reset:
Verify that the external power source is properly connected.
Verify that the external power supply has sufficient current
capacity to drive the PK-88.
Verify the 74HCT574 LED driver device at location IC9.
Verify that system clock Yl is operating and that a square wave
signal (4.9152 MHz, 0 to +5 volts) exists at IC16 pin 6. The
clock signal should be a moderately-distorted square wave.
PK-88 OPERATING MANUAL
6-2
TROUBLESHOOTING
PK88-176
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