Power Supply Ripple Level Check; Power Supply Charts; Us Power Supply - IBM 5251 Series Maintenance Information Manual

183
POWER SUPPLY RIPPLE LEVEL CHECK
The peak-to-peak output ripple level should be less
than 4 % of the respective dc voltages when measured
with an oscilloscope.
When an oscilloscope is not available, ripple voltage can
be observed by using the multimeter with the dB
adapter as follows:
1. Set the dB adapter to Bridge mode.
2.
Set the Range switch to
0
dB.
3.
Connect one of the dB adapter leads to frame
ground and the other lead to the DC voltage in
question.
Line
Voltage Black
Voltage
115
White
182, 183, 184
Line
Filter
Limits
Power
Switch
104 to 126 Vac
4.
5.
Change the setting on the Range switch until the
meter heedle is as close as possible to the
medium range.
Use the following table to determine if your supply
has an acceptable ripple level:
Power Supply Acceptable
Voltage
Ripple Level
±5 V -21 dB to -60 dB
+8.5 V -17 dB to -60 dB
184
POWER SUPPLY CHARTS
US Power Supply
Circuit
Breaker
---_
. .
Low Voltage
Connector
120 Vac
Display
Assembly
Connector
Pin
2
3,5,6
1,4,7,8
9
Power Supply
Printed Circuit
Board
Description
-5V
+5V
Ground
+8.5V
Maintenance Procedures 5251 MIM 1-101