HP 8508A - Page 118

Service
Test Switch Procedure Result
Position
Key Switches 4 Press any key on the Green LED on the processor should flash and
; " front panel the number for the key pressed should appear
in the display. Key numbers are shown in the
table below.
If the green LED does not flash and the
display does not show the key number, the
keyboard is suspect.
If Green LED flashes but no Key No. is
displayed, then Processor Assembly is suspect.
Display LED’s 5 The display should come If there is no Display, check the +5 volt supply .
on in a cyclic manner. to the Front Panel.
If only part of the Display comes on, check the
LEDs. Otherwise, replace the Front Panel
Circuit Board.
NOTE: The LEDs forming the main part of the Front Panel Display are available as a set that has been matched
for intensity level. Although the LEDs are available on an individual basis there can be no certainty that the replace-
ment will match the installed LEDs in intensity. The preferred replacement Front Panel Assembly is HP part
number 08508-60101. This assembly is supplied without the Display LED’s installed thus permitting re-use of the
LED’s from the defective assembly.
Keycode Description
1 A
2 B
3 REFL MEAS
4 FORMAT
5 POWER MEAS
6 B/A MAG
7 B-A PHASE
8 REF SELECT
9 REF
10 SYSTEM IMPD
11 METER SELECT
12 LOCK RANGE
13 STEP UP
14 STEP DOWN
15 MAG RANGE
16 HOLD VALUE
17 - DISPLAY
18 SHIFT
19 LCL
20 PRESET
8-8 E1089
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