Powertronix Quasar Service Manual page 100

Test Procedures
Single SCR and Diode Pack Replacement. (S7 S8)
1.
2.
3.
SCR S7
4.
5.
6.
7.
8.
Note: There is no connection to SCR terminal 3.
9.
Note: There is a de coupling capacitor linking the heatsink from SCR mounting
SCR S8
10.
11.
12.
13.
14.
15.
SCR fitting is the reverse of the removal procedure.
Figure 7-14 Single SCR Test.
Test lamp
+ve
+ve
7 - 24
Power down the UPS and carry out the DC bus discharge routine.
Gain access to the UPS power section by removing the top and side covers.
To gain access to the SCR's disconnect and remove the Input Filter PCB Part NºOSDE0079.
Follow the procedure on
Disconnect the Red and Black gate drive Connectors from 4Q1 (red) and 5K1 (black).
Disconnect the Battery negative bus bar from SCR terminal 2.
Disconnect Fuse F4 bus bar from SCR terminal 1.
Disconnect black leads from R2 to SCR terminal 1 and 2.
Remove red leads from SCR terminal 1 and 2 which connect to the fast on connectors F12
(SCR 1) and F11 (SCR 2) on the Inverter driver/feedback PCB.
Remove the two SCR Allen retaining screws from the SCR and lift from the Heatsink.
screw to the neutral bus bar.
Disconnect the battery +ve cable from SCR terminal 3.
Disconnect red leads from R1 to SCR terminal 1 and 2.
Remove fuse F1 bus bar from SCR terminal 2.
Remove the input bridge bus bar from SCR terminal 1.
Remove red leads from SCR terminal 1 and 2 which connect to the fast on connectors F13
(SCR 1) and F14 (SCR 2) on the Inverter driver/feedback PCB.
Carry out the following functional test on each SCR and replace if required.
9 volt power
source
ve
9 volt power source
and switch
page 7 38.
Single SCR & Diode pack
ve
Service Manual
3x3 UPS
Issue 2 - November 2001