2. Service
Assembly/Module Diagnostic Trees (Diagnostic Section 3)
122
3.9.1.3 A6J4.1 and A6J4.9. Reference Voltage Test
1 Verify reference voltages on A6J4.1/A6J4.9. with a DMM:
A6J4.1 (nominal 5.000) 4.995 and 5.005 volts
A6J4.9 (nominal -5.000) -5.005 and -4.995 volts
QUESTION: Are the voltages correct?
If Yes: Go to, 3.9.1.4.
If No: Remove power. Check fuses A6F1 and A6F2. If blown, replace
and repeat this step. If not blown, replace A6, and retest.
Top of A6 Board
z z Pin 9
z z
z z
z z
z z J4 Jumper Layout
z z
z z
z z
z z Pin 1
3.9.1.4 EFC Voltage Test (1)
1 Record the position of the jumper connecting the left-hand row of
pins of A6-J4 with the right-hand. (The jumper positions number
1 through 9, beginning at the bottom.)
2 Use the INFO/Ctrl menu to determine the EFC control voltage as
a percentage between -100% and +100%.
3 Calculate the expected EFC control voltage using the formula:
Control voltage=1.25
*
(5-Pos.Jmpr)-0.03308
*
(%Ctrl). For example, if the
jumper is in the 6 position and the control is +8%,
control voltage = 1.25
*
(6) -0.03308
*
(8) = 7.24.
4 Measure the EFC control voltage applied to the oscillator at A6J6.
5 Verify that the measured and calculated voltages agree to within
0.03 volts.
QUESTION: Do the measured and calculated EFC voltages agree to
within 0.03 volts?
If Yes: Go to, 3.9.1.5.
If No: Go to, 3.9.1.4.1.
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