Channel-To-Channel Isolation Tests - Keithley 7999-2 Instruction Manual

4-6 Service Information

Channel-to-channel isolation tests

CAUTION
Perform the following steps to check channel-to-channel isolation:
1.
2.
3.
4.
5.
6.
7.
8.
Figure 4-3
Channel-to-channel
isolation connections
INPUT
PREAMP OUT
!
250 PEAK
INPUT
250V PEAK
TEMP
TYPE K
OPTION SLOT
CAUTION: CAUTION:
The following procedure uses the Model 6517A voltage source to measure
resistance. To avoid damage to the Model 7999-2, use the Model 6517A
manual ohms mode to limit the test voltage to 30V as outlined in the proce-
dure.
Turn on the Model 6517A Electrometer, and allow the unit to warm up for one hour
before testing.
Select the Model 6517A ohms function and 2G Ω range, and enable zero check. Make
sure the voltage source is in standby.
Connect the electrometer to the two Model 7999-2 channels being tested, as shown in
Figure 4-3. Note that electrometer INPUT HI is connected to one channel, while
VOLTAGE SOURCE HI is connected to the other channel.
Put the Model 6517A in the manual ohms mode, and set the voltage source to +30V.
Place the Model 6517A voltage source in operate, and disable zero check.
Allow the reading to settle, then verify that the resistance reading is >1G Ω .
Enable zero check, and place the Model 6517A voltage source in standby.
Repeat steps 3 through 7 for all other two-channel combinations on the card.
Voltage Source HI
WARNING: WARNING:
NO INTERNAL OPERATOR SERVICABLE PARTS,SERVICE BY QUALIFIED PERSONNEL ONLY.
NO INTERNAL OPERATOR SERVICABLE PARTS,SERVICE BY QUALIFIED PERSONNEL ONLY.
1010V
PEAK
HI
LO SELECTED
LINE VOLTAGE
90-110V 180-220V
COMMON 2V ANALOG
V SOURCE
105-125V 210-250V
OUTPUT
750V
LINE RATING
PEAK
50-60HZ
50VA MAX
AC ONLY
HUMIDITY
EXT TRIG MTR COMP
IN OUT
RS232
DIGITAL TRIG LINK
I/O
!
INTERLOCK
FOR CONTINUED PROTECTION AGAINST FIRE HAZARD,REPLACE FUSE WITH SAME TYPE AND RATING.
FOR CONTINUED PROTECTION AGAINST FIRE HAZARD,REPLACE FUSE WITH SAME TYPE AND RATING.
Model 6517A Electrometer
Connect INPUT HI
to First Relay
MADE
IN
U.S.A.
LINE FUSE
SLOWBLOW
1/2A 90-125V
1/4A 180-250V
IEEE-488
(CHANGE IEEE ADDRESS
WITH FRONT PANEL MENU)
Connect Voltage
Source HI to
Second Relay
In
H
L
G
Out
In
H
L
G
Out
Model 7999-2 Relays Under Test. See
Section 2 for Detailed Connections.
Close
Relay
Close
Relay