Recalibration Of Assembled Power Supplies - TTI TSX Series Service Manual

board) for about 34V OVP display. Rotate VR10 fully ACW. The display should indicate
"TRIP". Switch off. Allow time or discharge HV reservoirs C9,10.

Recalibration of Assembled Power Supplies

1. Preparation - Ensure voltage selector is in the appropriate position and HV bridging
connector present. Connect common mode test network to rear terminal block as shown
in Fig 3. Close the test network switch. Set the Voltage and Current controls to minimum.
Switch Output off. Switch on. The CV and CI LEDs should be off, the Output LED on and
both displays reading zero. Switch Output off.
2. Control Board Adjustments (non-programmable versions only) - Connect the DVM
between 0V and IC7-A on the main PCB pin 13. Note the DVM reading which should be
within 3 mV of zero. Switch Output on. If necessary adjust VR5 on the control board to
maintain the same DVM reading. SWITCH OUTPUT OFF to avoid destroying test
network. Advance Voltage and Current controls to maximum. Adjust VR6 on the control
board for a Voltage display of 35.3/18.15V. Adjust VR7 on the control board for a Current
display of 10.2/20.2A.
3. Set Voltage Zero - Move DVM to rear sense terminals. Set Voltage control(s) to minimum
and Current control for about 0.2A. Switch Output on. The CV LED should be on and the
Output LED off. The Current and Voltage displays should both read zero. Adjust VR3 until
the DVM reads within 5mV of zero. Set the Current control to minimum. The DVM should
read between -0.7V and -0.15V. Switch Output off. The DVM should read between -0.15
and -0.25V.
4. Set Current Zero - Connect 10Ω 10W load to output terminals. Set Voltage control(s) to
display about 4V and Current control to minimum. The CI LED should come on. Adjust
VR8 for zero DVM reading within 20mV. Note and avoid saturated region below about -
20mV. Disconnect load after test.
5. Adjust CMRR - Set the Current control for about 0.2A. Note the DVM reading. Open the
switch on the test network and if necessary adjust VR1 to remove about half the
difference. Close the switch and repeat the process until the DVM reading is the same for
both switch positions. Switch Output off. Disconnect the test network and link adjacent
sense and output terminals.
6. Set Maximum Voltage - Set Voltage control(s) to maximum. Switch Output on. The CV
LED should be on. The Voltage display should read 35.3/18.15V. Adjust VR2 until the
DVM reading matches the Voltage display. Switch Output off.
7. Adjust Measured Current Display - Connect 3.75/0.90hm load in series with the current
meter. Set preset VR9 fully ACW. Set the Current control to maximum. Switch Output on.
Adjust VR9 until the current display reading matches the current meter. The CV LED must
remain on. Switch output off.
8. Adjust Measured Voltage Display - Connect 2.75/0.60hm load in series with the current
meter. Switch Output on. The CI LED must remain on. Adjust VR4 until the Voltage display
matches the DVM reading. Switch Output off. Disconnect the load.
9. Adjust OVP Trip - Set preset VR10 fully CW. Set Current control to about 0.5A display.
Set Voltage control(s) for 34.00V display. Set the user OVP preset (VR3 on the control
board) for near 34V OVP display. Now slowly adjust preset VR10 ACW until the display
indicates "TRIP". Reduce the Voltage control(s) by about 5 per cent and turn the supply
off briefly to reset the supervisory logic. Then recheck the trip point by increasing the
Voltage control(s) gradually until OVP trip occurs.
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