HP 8550 Service Manual - Page 320
List of variable resistors (VR), LEDs, check pins by PCB, must not be touched during field service.
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Note Note List of variable resistors (VR), LEDs, check pins by PCB Only the LEDs and check pins that need to be checked during field service are listed below. Check pins not listed below are only for factory use, and their adjustment and checking requires special tools and measurement instruments. Their adjustments require a great degree of accuracy and must not be touched during field service. Some LEDs leak a small amount of current even when normal, and therefore glow faintly even when they are off. Do not mistake the faint glow for the LEDs being on. 318 Chapter - 5 Theory of operation EN
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318
Chapter - 5
Theory of operation
EN
List of variable resistors (VR), LEDs, check
pins by PCB
Only the LEDs and check pins that need to be checked during field
service are listed below.
Note
Check pins not listed below are only for factory use, and their
adjustment and checking requires special tools and measurement
instruments. Their adjustments require a great degree of accuracy and
must not be touched during field service.
Note
Some LEDs leak a small amount of current even when normal, and
therefore glow faintly even when they are off. Do not mistake the faint
glow for the LEDs being on.