Service manual

14 Getting Started Chapter 1
Diagnostic Connector
The 25-pin Sub-D diagnostic connector provides access to backplane
voltages, power supply and backplane temperatures, and output signals. The
pins are described in Table 1-1.
Table 1-1. Diagnostic Connector Pin Descriptions
Pin # Function Description
1 +5 VM +5V backplane voltage monitor (high impedance). (+4.875 Vdc to +5.125 Vdc)
2 -12 VM -12V backplane voltage monitor (high impedance). (-12.6 Vdc to -11.64 Vdc)
3 -24 VM -24V backplane voltage monitor (high impedance). (-25.2 Vdc to -23.28 Vdc)
4 -2 VM -2V backplane voltage monitor (high impedance). (-2.1 Vdc to -1.9 Vdc)
5 Rem On Remote power on. See “Using the Remote Power-on Pins.”
6 +5 VC +5 VDC source output (1A maximum).
7 +12 VC +12 VDC source output (1A maximum).
8 +5 V Stdby Input for +5V STDBY (1A maximum for pins 8 and 21 combined).
9 GND Chassis ground.
10 SysReset * TTL low-true input signal causes system reset, output indicates system reset.
11 PS Temp Output voltage proportional to power supply temperature (0 VDC at 0 °C, with a rise of
10 mV per degree centigrade).
12 Ref Temp Output voltage proportional to backplane temperature (0 VDC at 0 °C, with a rise of 10 mV
per degree centigrade). A function of the ambient temperature and load.
At no load, T
ref
~ 2 °C + ambient. At full load and high fan speed,
T
ref
~ 14 °C + ambient. At full load and low fan speed, T
ref
~ 20 °C + ambient.
13 Fans OK * TTL low-true output voltage indicates power supply and backplane cooling fans are
operating.
14 +12 VM +12V backplane voltage monitor (high impedance). (+11.64 Vdc to +12.6 Vdc)
15 +24 VM +24V backplane voltage monitor (high impedance). (+23.28 Vdc to +25.2 Vdc)
16 -5.2 VM -5.2V backplane voltage monitor (high impedance). (-5.46 Vdc to -5.044 Vdc)
17 GND Chassis ground.
18 REM Rtn Remote power switch return. See “Using the Remote Power-On Pins.”.
19 V OK * TTL low-true output voltage indicating the +5V, ± 12V, ± 24V, -5.2V, and -2V power supply
voltages are within ± 8% of its allowed variation.
20 GND Chassis ground.
21 +5 V Stdby Input for +5V STDBY (1A maximum for pins 8 and 21 combined).
22 GND Chassis ground.
23 ACFAIL * TTL low-true output asserted by the mainframe power monitor at power down or whenever
a loss of power is detected.
24 GND Chassis ground.
25 RSV
Reserved.
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