Adjustments
Model 3585A
5-6
j . Connect the DVM to A72TP l . Adjust A72R3 1 for 5.4V ± 0.05V.
k. Turn the 3585A power off. Remove PC boards A71 and A72.
l. Disconnect the cable from A 7013 . Replace PC boards A 71 and A 72.
m. Connect a 1 0, 25W resistor from A72TP 1 to chassis ground.
WARNING
The
10
resistor used for this adjustment can reach a temperature
that witrcause burns. Handle this resistor with caution.
n. Turn the 3585A power on. Adjust A72R19 so that the yellow current limit indicator
just goes out.
o. Turn the 3585A power off. Disconnect the resistor from A72.
p. Remove the A7 1 and A72 board. Reconnect the cable associated with A7013 . Replace
the A71 and A72 boards.
q. Using a DVM, check each of the voltages below to verify that the various power sup
plies are working properly.
A74TP 1
A73bTP1
A73aTP 1
A71TP1
- 1 8V ± 0.9V
+ 1 8V ± 0.9V
+ 1 2V ± 0.6V
+ 7.7V ± 0.6V
r. Disconnect the DVM. Replace the PC board Hold-down bar and the plastic cover for
the power supplies. This completes the Low Voltage Power Supply Adjustments.
5· 7. 90MHz Reference Board Adjustments (A2 1 )
NOTE
The same frequency counter and reference should be used for all
reference oscillator adjustments.
This adjustment sets the frequency of the 90MHz crystal oscillator on the A21 board. This
crystal oscillator is used during warm-up and in the absence of an EXT REF INPUT.
a. Disconnect the cables from A2I J 1 and A2I J7.
b. Connect a frequency counter to A2I J 1 .
c . Adjust A21 R125 (see Figure 5-46) for a frequency reading o f 90MHz ± 20Hz.
d. Reconnect the A2I J7 cable if continuing with Oven Output Shutdown Adjustments.
Reconnect the A2I J 1 and A2I J7 cables if not continuing.