3
Checking and Adjusting DPU Power Supply
Chapter 3 describes how to measure and adjust power supply voltage levels.
The data parallel unit (DPU) has four power supply output levels: +5 V, –5.2
V, +12 V, and –12 V. Measure these voltages at the DPU backplane, at the test
points shown in Figure 3–1. For DECmpp 12000 systems adjust the voltage
levels at the points shown in Figure 3–2. For DECmpp 12000–LC systems
adjust the voltage levels at the points shown in either Figure 3–3 or Figure 3–4,
depending on the power supply used in the system.
Warning
Physical tolerances are very tight at the power supply. 5 V current levels
are in the 600 A range.
Do not short the power supply leads to ground or to other power supply
leads.
Do not use conductive adjustment tools. Use only insulated tools.
When working around the power supply, do not wear loose clothing or
jewelry, especially watches or rings.
Failure to observe these precautions can cause personal injury and
damage to the equipment.
Checking and Adjusting DPU Power Supply 3–1
