2. Service
Top-Level Diagnostic Tree (Diagnostic Section 1)
59
1.4.4.2 Instrument AC Power Absent
1 Reconnect the internal standby batteries and reapply ac power. (For Opt.
048 reapply ac power).
2 Measure the dc voltage between TP5 on A11 and a common test point (not
chassis ground), such as TP6,9, or 12 on A11.
3 Verify that the voltage is between 32 and 38 Vdc and record results.
QUESTION: Is the voltage 32 - 38 Vdc?
If Yes: Remove power, replace A11 (probable CR14 fault), and retest.
If No: Go to, 1.4.4.2.1
Verify that the voltage is between 45 and 51 Vdc and record results.
QUESTION: Is the voltage 45 - 51 Vdc?
If Yes: Remove power, replace A11 (probable CR14 fault), and retest.
If No: Go to, 1.4.4.2.1
1.4.4.2.1 A1C4 Voltage Test Procedure
1 Measure the dc voltage across A1C4 (large-can filter capacitor).
QUESTION: Is the voltage between 32 and 38 Vdc?
If Yes: Remove power, replace faulty 05071-60253 cable, and retest.
If No: Go to, 1.4.4.3.
QUESTION: Is the voltage between 45 and 51 Vdc?
If Yes: Remove power, replace faulty 05071-60253 cable, and retest.
If No: Go to, 1.4.4.3.
1.4.4.3 LF1/T1 Transformer Fault Verification
1 Measure the 60 Hz ac voltage between CR3 pins 2 and 3 on the
A1 (motherboard) assembly.
2 Verify presence of 25-35 Vrms. (33-47 Vrms for Opt. 048)
QUESTION: Is the voltage between 25-35 Vrms?
(33-47 Vrms for Opt. 048)
If Yes: Remove power, replace A1, (or A1CR3), and retest.
If No: The LF1 line filter/cable assembly (05071-60259) or toroidal
power transformer T1 (9100-4962, (9100-5134 for Opt. 048)), may
be each or both at fault. Ensure that F1 line fuse is not open, then replace
LF1/T1 and retest.
Opt. 048
Opt. 048
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