2. Service
Top-Level Diagnostic Tree (Diagnostic Section 1)
38
If Yes: Go to, 1.0.2.
If No: Disconnect power immediately and check the appropriate rear panel
power fuse.
If fuse is intact, Go to, 1.0.1.1. (For Opt. 048 Go to 1.0.1.1.0.)
If fuse is blown, Go to, 2.1.1.1.0 (Power supply diagnostic tree).
1.0.1.1.0 DC Input 1 and 2 Power Steering
Circuit Check
1 Use the DC Input 1 and 2 Power Steering Schematic (Figure 2-1.)
located on page 32 of this chapter to troubleshoot the dc power
input steering function.
QUESTION: Is the DC input power steering circuit functional?
If Yes: Go to, 1.0.1.1.
If No: Replace the 48V Sub-panel Assembly (P/N 05071-60277) and retest.
1.0.1.1 Digital Supply Voltage Check
1 Install the short extender board (part number 05071-60051) into
the spare slot on the A1 motherboard.
2 Use a DMM with a point-tipped probe to verify +5V supply on the
extender board test points.
QUESTION: Is +5V between 5.28 to 5.50 volts?
If Yes: Go to, 1.0.1.2
If No: Go to, 2.1.1.1.0 (Power-Supply diagnostic tree).
1.0.1.2 A3 Microprocessor Fault
1 Observe upper edge row of LEDs on A3 microprocessor
assembly.
QUESTION: Are LED DS6 lit and LEDs DS1 - DS4 extinguished?
If Yes: Remove power, replace A13 (see page 159.), and retest.
If No: Remove power, replace A3, and retest.
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