HV Imon in 1th MTCC period POWER CYCLE A. Cimmino - P. Paolucci - G. Polese 09-11-2006 / Joint RPC-Trigger meeting P. Paolucci - I.N.F.N. Napoli

HV Imon test with Resistors at 904 31 c 31 c WITHOUT FAN UNIT 31 c 20 c WITH FAN UNIT 20 c 20 c A. Cimmino - P. Paolucci - G. Polese 09-11-2006 / Joint RPC-Trigger meeting P. Paolucci - I.N.F.N. Napoli

HV power cicle test with Resistors at BLG 904 POWER CYCLE B2 CHO/1 BOARD 1 CH0/1 BOARD 1 CH2 NO FAN-31C NO FAN-31C BOARD 2 CH0/1 BOARD 3 CH0/1 NO FAN-31C FAN-20C A. Cimmino - P. Paolucci - G. Polese BOARD 3 CH2 BOARD 4 CH0/1 FAN-20C 09-11-2006 / Joint RPC-Trigger meeting FAN-20C P. Paolucci - I.N.F.N. Napoli

Sotware and Hardware Reset test SW HW A. Cimmino - P. Paolucci - G. Polese 09-11-2006 / Joint RPC-Trigger meeting P. Paolucci - I.N.F.N. Napoli

I0set influences Imon readout I0 changed from 800 microA to 750 microA A. Cimmino - P. Paolucci - G. Polese 09-11-2006 / Joint RPC-Trigger meeting P. Paolucci - I.N.F.N. Napoli

HV conclusion We were able to reproduce the instability effect at BLG 904 using resistive charge  problem is not related to the detector/cable Measuring independently the current on the ground wire we understood the instability was on the monitored current (Imon) and not on the generated current. The increase let us suspect to a thermal drift of some components and so we begin to use the CAEN fan unit to ventilate the boards. Using the fans the board temperature went down from 31oC to 20oC and for 6 days Imon was very stable but increased on the 7th The s of the Imon distribution of the ventilated boards is 0.2 mA and it was twice without fan. Software power cycle do not affect the Imon (offset is constant) Hardware power cycle of any board present in the EASY crate affect the offset of all the boards in the crate. CAEN got all the results and is now trying to reproduce them in their lab. Some critical components has been found !!!! A. Cimmino - P. Paolucci - G. Polese 09-11-2006 / Joint RPC-Trigger meeting P. Paolucci - I.N.F.N. Napoli