Readback Dac Circuits; Readback Multiplexer (U20) - HP 6033A series Service Manual

CV DAC Circuits
Node Setup
U69-6 Voltage set to 0.
Voltage set to max.
U64-6 Voltage set to 0.
Voltage set to max.
CC DAC Circuits
Node Setup
U68-6 Current set to 0.
Current set to max.
U65-6 Current set to 0.
Current set to max.

Readback DAC Circuits

Refer to Figure 3-4 for the waveforms to troubleshoot the readback circuits.
The turn-on selftest waveforrn at U24-7 is obtained by toggling the on/off switch repeatedly to perform the selftest routine.
If this waveform is not correct, isolate the problem either to the readback DAC or the multiplexer.
Note:
To troubleshoot the readback DAC from the front panel if the unit has failed selftest, place jumper A8J5
in the skip selftest position (see Table 3-2). This lets you operate the unit even though it fails the internal
selftest.
Use the front panel controls to vary the output voltage from zero to full-scale output to obtain the waveforms at U67-6.
These waveforms check the operation of the readback DAC.
To check the multiplexer, use the front panel controls to obtain the waveforms at the output of the multiplexer (U24-2).
Remember to turn off the unit and connect a short across the output before programming the current from zero to full scale.
Press "OVP DISPLAY'' on the front panel to display the OV_MON portion of the waveforms.
If the waveforms are not correct, use the front panel controls and a DMM to check the multiplexer input voltages at the
following nodes:

Readback Multiplexer (U20):

Node Setup
U20-9 Voltage set to 0.
Voltage set to max.
U20-10 Current set to 0.
Current set to max.
U20-11 OV set to 0.
OV set to max.
Measurement
0V
+ 5V
0V
-10V
Measurement
0V
+ 5V
0V
-10V
Measurement
0V
+ 5V
0V
+ 5V
0V
+2.2V
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