5-15.
ALC ADJUSTMENTS (Cont’d)
Equipment
Power Supply
HP 6294A
Digital Voltmeter (DVM)
HP 3456A
1 Megohin Resistor
HP P/N 0757-0059
0.1 UF Capacitor
HP P/N 0160-0168
Extender Board
HP P/N 08350-60031
Procedure
1.
Disconnect AC power cable from the OUT and allow
it to cool for at least two
hours.
2.
Disconnect cables W26 and W27 from A25J2 and A25J1 respectively (Figure 5-46), and remove
the A25 PC board from the instrument.
A25
Ji
J2
“H”
“L”
Ri 15
R37
R36
Ri 09
R80
EX
—
3.
Install an Extender Board in place of A25.
4.
Set the DVM for Ohms measurement and connect the input between pins 4 and 26 of the extender
board. Note the resistance measured. This value is thermistor resistance, RT, and will be used for
calculations in later steps.
5.
Connect the test equipment as shown in Figure 5-45 with cable W27 connector connected to an
SMB-to-BNC adapter.
6.
Connect the
DVM
across the output terminals of the Power Supply
and
adjust
the power supply
output for 5.00±0.01Vdc. Move the DVM connections back to the SMB-to-BNC adapter as
shown in Figure 5-45.
Figure 5-46.
ALC Detector A25 Temperature Compensation Adjustments Location
5-90
Adjustments
HP 8340B/41B