3 . Connect the positive ( +) lead of the voltmeter to AlTP3 or AlTP2 on the HP 1653B, System Board Assembly.
on the HP 1652B,
4. Connect the power cord to HP 1652B/1653B and turn on the instrument. 5 . Assign pod 3 of the HP 1652B, or pod 2 of the HP 1653B, to a machine in the System Configuration menu by using front-panel knob and SELECT key. 6 . Press the CHAN/FORMAT key and set the User-defined pod threshold of the pod assigned in the previous step to -9.9 V. Refer to the following steps if you are unfamiliar with menus. a. Move cursor to the pod threshold field (TTL) with the front-panel knob and press SELECT. b. Move the cursor to User-defined with the front-panel knob and press SELECT. c. Use the front-panel keys to enter the value -9.9 V. Then move the cursor to Done and press SELECT. The voltmeter readout should indicate a voltage value within the range of 0.975 v to -1.005 v (0.990 v 20.015 V). Set the User-defined pod threshold of the pod assigned in step 6 to + 9.9 V. Note voltmeter readout. The voltage reading should be within the range of + .975 v to + 1.0005 v (+ .990 v to.015 v). 10. If either voltage reading is not within the given range, use the following procedure to adjust the threshold level. a. Turn off the instrument and disconnect the power cable.
Caution
Never attempt to remove or install any assembly with the instrument ON or the power cable connected. This can result in component damage. b . Remove the oscilloscope assembly by following the procedure �Removal and Replacement of the Oscilloscope Assembly� in section 6D . c. Loosen the two screws that hold the rear bracket on the oscilloscope assembly support panel until the bracket moves freely. d . Remove the support panel by carefully tilting the rear of the panel up and lifting the panel out through the top of the instrument cabinet. Make sure the metal tabs on the front of the support panel clear the front panel. e. Reconnect the power supply using the power supply cable (HP part number 54503-61604). f . Reconnect the disk drive assembly cable to the disk drive. g . Reinstall the oscilloscope assembly without the support panel to allow unabstracted access to AlR95. h . Reconnect the oscilloscope assembly to the system assembly with the appropriate cable.
