Safety Review Document for the Preamplifier System for the Bo LArTPC ----------------------------------------- Rev. Date 12-July-2008 This document covers the preamplifier system and its power supply that are the front-end of the Bo Cryostat LArTPC DAQ system. The contact person for this equipment is: Dan Edmunds Fermi Phone: x2832 MSU Phone: 517-884-5521 Email: edmunds@pa.msu.edu These preamplifiers are located in the large green "preamplifier box" on top of the Bo cryostat which is in the main high bay area of the Proton Assembly Building (PAB). The power supply for these preamplifiers is located in the Bo DAQ rack that is next to the Bo cryostat. The components of this system (given in the order of the power flow) are: Preamp Power Supply, Preamp Power Cables, Preamp Fuse Panel, PMB-16 cards. Each of these components is described in a section of this note. Preamp Power Supply ------------------- The Preamp Power Supply chassis contains 4 separate commercial linear open frame power supplies. A schematic drawing of the Preamp Power Supply is available at: www.pa.msu.edu/~edmunds/LArTPC/Bo_LArTPC_DAQ/Safety_Review/ preamp_power_supply.pdf The 4 supplies in the Preamp Power Supply chassis provide power to 6 different loads on the PMB-16 cards. The supply voltages and loads are: The +8 Volts supply provides about 1.3 Amps to the FET Vcc load and about 0.6 Amps to the DRV Vcc load The -6 Volts supply provides about 0.3 Amps to the FET Vee load and about 0.6 Amps to the DRV Vee load The +5 Volts supply provides about 2.5 Amps to the Filter Vcc load The -5 Volts supply provides about 2.5 Amps to the Filter Vee load The +8 Volt supply is an Elpac Model SOLV30-12 that is rated for 12 Volts output at 4 Amps. This supply has been adjusted down to 8 Volts by changing a feedback resistor to the uA723 regulator chip and by including two 0.5 Ohm resistors before the bulk DC bridge rectifier to reduce the bulk DC supply and thus reduce the heat dissipated by the 2N3055 pass transistor. The -6 Volt, +5 Volt, and -5 Volt supplies are all Elpac model SOLV30-5. This model supply is rated for 5 Volts at 4 Amps. The 6 Volt output is within the stock adjustment range of the supply. All 4 supplies are protected by 2 Amp fuses at their input and by 5 Amp fuses at their output. These fuses are located immediately adjacent to each supply. In addition the AC power coming into the Preamp Power Supply chassis has a 5 Amp fuse in each side of the line before it goes to any loads. There are separate front panel indicator LEDs and tip jack test points for each of the 4 supplies. These components and wiring are protected by separate 3 Amp pico fuses located immediately adjacent to the supply's output terminals. The DC output from the Preamp Power Supply chassis is provided on two Wieland terminal strips. These are used to connect the power supply chassis to the Preamp Power Cable that runs over to the Preamp Box on the Bo cryostat. An early picture of the Preamp Power Supply is available on the web at: www.pa.msu.edu/~edmunds/LArTPC/Bo_LArTPC_DAQ/PMB_16/ pict_preamp_power_supply.jpg Preamp Power Cable ------------------ The Preamp Power Cable is about 15 ft long and carries the DC power from the Preamp Power Supply chassis over to the Preamp Box on the Bo cryostat. This power cable is shown in the following schematic drawing on the web at: www.pa.msu.edu/~edmunds/LArTPC/Bo_LArTPC_DAQ/Safety_Review/ preamp_power_cables.pdf This cable carries power for 3 different circuits on the PMB-16 preamplifier cards. These circuits are: "FET", "DRV", and "Filter". Each of these circuits uses a Vcc and a Vee supply. There are 4 wires in the power cable for each circuit: a Vcc wire, a Vee wire, and two return wires. All of these wires are 14 AWG with 105 deg C insulation. Each set of 4 wires is twisted together. There is a woven plastic sleeving around the overall cable. At the Preamp Box end of the cable there are 3 Cinch-Jones connectors, one for each circuit. The Vcc and Vee supply for each circuit are both carried on one contact of the Cinch-Jones connector for that circuit. The return line for that circuit is carried on two contacts and the alignment pin of the connector. Each contact of the connector is rated for 15 Amps. Preamp Fuse Panel ----------------- At the Preamp Box the DC power is received on 3 Cinch-Jones connectors. From these connectors the power runs over to a fuse panel through 14 AWG wires. This #14 wiring is setup the same way as in the Preamp Power Cable. The Preamp Fuse Panel is shown in the following 2 drawings. All of the parts are mounted on one panel but 2 drawings were used for clarity. www.pa.msu.edu/~edmunds/LArTPC/Bo_LArTPC_DAQ/Safety_Review/ preamp_fet_drv_fuse_panel.pdf preamp_filter_fuse_panel.pdf The fuse panel has fuses and output cables to supply power to 6 PMB-16 cards. There is a 2 1/4 Amp fuse in each of the 6 supply voltages that go to each of the 6 PMB-16 cards. The cables that carry the power from the fuse panel to each PMB-16 card are made with 22 AWG wire. Each PMB-16 card has one cable for its "FET" and "DRV" power and another cable for its "Filter" power. The connectors that plug these cables into the PMB-16 cards are make with 12 position AMP MOD IV housings and AMP high pressure contacts. The contacts are AMP/Tyco part number 1-87309-4 Newark stock number 90F3791. These contacts are rated for 3 Amps each. The current rating specification for these contacts is available from AMP/Tyco web site at: http://catalog.tycoelectronics.com/TE/bin/ TE.Connect?C=1&PN=1-87309-4&M=BYPN&LG=1&I=13 The following picture shows the Preamp Fuse Panel installed on the top inside surface of the outer green Preamp Box. You can also see the Preamp Power Cable entering from the left hand side with its 3 Cinch-Jones connectors. The cables that feed power to the individual PMB-16 cards are visible at the bottom of the inner white Preamp Box. www.pa.msu.edu/~edmunds/LArTPC/Bo_LArTPC_DAQ/ pict_preamp_box_with_one_card.jpg In the same web directory see also the picture: pict_fuse_panel_in_box.jpg PMB-16 Cards ------------ The PMB-16 cards receive "already fused power" on 2 connectors. Each connector is a 12 pin header of 25 mil square pins. One connector is for the "FET" and "DRV" power and the other connector is for the "Filter" power. Once the power is on a PMB-16 card, the card is protected from spikes and reverse polarity by a Transient Voltage Suppressor on each of the 6 supplies. Each supply is also cleaned up by bulk Aluminum Electrolytic and Tantalum capacitors before they reach the actual electronics components on the card. The PMB-16 card can been seen in the following picture on the web. You can see where the power is received on the PMB-16 card near the bottom of this picture. www.pa.msu.edu/~edmunds/LArTPC/Bo_LArTPC_DAQ/ pict_pmb_16_card_in_box.jpg The power connectors on the PMB-16 card are rotationally symmetric, i.e. if one is plugged in rotated by 180 deg it makes no difference. If a connector is plugged in offset by one pin then it will directly short circuit the supply and blow the 2 1/4 Amp fuse (the card itself will not see any significant supply voltage). If the connector for the "FET" and "DRV" supplies is exchanged with the connector for the "Filter" supply nothing is damaged. The PMB-16 card will not work well with these connectors interchanged but nothing is damaged. Gerber files of the layers on the PMB-16 card that carry power can be made available for review. The power is carried on power planes so there is not really an issue about sufficient trace width to match the 2 1/4 Amp fuses that protects the card.