Equipment Issue during shift

-HV standby error/HV range error during 4 layers process. -Error during Cr initial ramping power, wafers in chamber. -Checked HV triode tube glowing. -Checked plug-in PCB U2, U3 and U5 power supply board. -contact cleaned U2 and U3 PCB. -Measured +-15Vdc and 24Vdc from ext PS ok. -Tested HV standby ok but HV range error persisted -Coil current ok. reset EEC300 controller -ve. -Disconnected HV from red box to isolate chamber -ve. To continue. -----------------------------------G2------------------------------------ -PO said wafer cannot wait more than 24hours. -so vent chamber and take out wafer(NCL) -Dayshift no MS support,kindly to continue. ----------------------------------G1------------------------------------- -After vented chamber, checked/measured Egun shorted to gnd. -Found flake from chamber shields shorted Egun, cleaned up and tested -ve. -Probably flake shorted Egun after vented chamber. -Removed U4 grid ctrl board, power transistor IXTM10N100 and measured no shorted. -Measured U4 board, TP2=8.4V, TP3=86V, TP4=95V at HV off state ok. -Measured grid voltage -583V at U13 ok. -checked soldering points on board and installed back, tested HV 10KV ok. -Tested HV on/off few times, encountered HV range error intermittently. to continue. Status : Maint