Model 400S System Unit Cpu Board Voltage Test Points; Model 400S System Unit Power Supply Voltages And Tolerances - HP 400 Series Servicing Manual

Figure 4-21. Model 400s System Unit CPU Board Voltage Test Points
Table 4-20 lists the voltages that the power supply provides to the system unit.
Table 4-20. Model 400s System Unit Power Supply Voltages and Tolerances
Voltage (dc)
Continue with Step 4 or Step 5, depending on the result of your voltage checks.
4. If the DC output voltages are not present at the CPU board test points, perform
the following steps:
A. If the system unit has an ISA backplane, remove the right side and RFI
covers. Check the voltages on the ISA power distribution cable on the ISA
backplane as listed in Figure 4-24. If the voltages are present, replace the
CPU board. If the voltages are not present, go on to step B.
B. Check the ac outlet for power with a voltmeter. If the ac outlet power is
incorrect, an electrician must correct it.
Tolerance
+ 5 4.85 to 5.20 V dc
-5 -4.60 to-5.50 V dc
+ 9 8.70 to 9.30 V dc
+ 12 11.40 to 12.60 V dc
-12 -11.40 to-12.60 V dc
Fault Isolation 4-71