Testing Vicor Power Assembly

Test Setup

Required for this test procedure:

• VPA power supply to be tested
• 24 V 5A supply
• Winchester to Winchester pin to pin cable
• 48HP MCE crate, fully populated with cards including two revision E readout cards
• three 50 ohm MDM jumper boards
• MCE dummy load
• Ubuntu computer with MAS installed

DC Voltages

First, connect the VPA power supply to the MCE dummy load using a < 1m cable and measure the DC voltages. The voltages should be in the range:

• pVa: 6.1 to 6.3 V
• nVa: -6.1 to -6.3 V
• Vlvd: 4.4 to 4.7 V
• Vcore: 2.9 to 3.2 V
• Vah: not connected

With the VPA connected to the dummy load, observe the DC power supply voltages using an oscilloscope. There should be no obvious AC variation on the lines. The AC coupled RMS value of each power supply line should be less than 20 mV.

Noise Spectrum

Now, connect the supply to a full 48HP MCE with Rev E readout cards. Place 50 ohm jumper boards on all three MDM connectors at the back of the MCE. Connect the clock card fibres to a MAS computer, and on that computer, run the script 'psu_noise_raw_acq'. This script requires two arguments: readout card number (0 or 1) and readout card channel (1-8). Please use RC 1 channel 4. This script collects raw data and saves their spectra in the directory /data/cryo/<date in YYYYMMDD format>//spectrum.png.

On the scuba2 server, under scuba2:\public_html\sc2mce\system\psu_24V_Vicor\test_res\, create a directory named for the serial number of the VPA power supply under test. Copy the spectrum.png file from the MAS computer to this directory on the scuba2 server.