Procedure for Removing SPARO from Viper

Viper elevation 27 degrees should work well for removal.
The overhead crane (Fig. 6) should be installed ahead of time.
These instructions assume that SPARO's pumped pot is not being pumped on when the removal process begins. We assume that it has been in equilibrium at ambient pressure for at least a few hours before starting the removal process.
Steps 1-5 can be performed at a leisurely pace, with time to rest between steps.
Steps 6-9 should be done sequentially, without long delays between steps.
Step 10 can be performed later, at your convenience.

Fig 1 - SPARO on Viper (2003) - showing bias switch on one of the preamps, the connector ring, the focus bolt, and the pumped pot vacuum valve.

Turn off AC power to SPARO blue box. The switch is located in the Viper control room, opposite the door, and is labelled "SPARO". Note that this switch may also control the chopper encoder (I'm not sure) so the chopper should be off.
Unplug the half-wave plate stepper motor cable at SPARO's connector ring. The connector ring is an aluminum ring about 20 inches in diameter (see figures 1 and 4).
Open the SPARO blue box (figure 2) and unplug the AC power to the indexer (figure 3). Note: this step requires rotating the telescope 180 degrees such that the SPARO blue box is accessible.
Turn on the power to the SPARO blue box. Recall that the switch is in SPARO control room. This step allows the fans in the blue box to resume circulating the heat.

larger	Fig 2 - SPARO blue box and ACBAR blue box (2001).
larger	Fig 3 - inside of SPARO blue box (2001), showing indexer.
larger	Fig 4 - SPARO on Viper (2001), showing focus bolt, connector ring, and feedthru ring.

Signal Cables (x2): Stiff white cables with 25-pin "D" connectors which attach to the preamps.
Preamp Power (x2): These cables first need to be disconnected from the batteries in the pump room and then from the SPARO preamps. Where they connect to SPARO preamps, these are 9-pin D connectors.
³He pressure sensor cables (x2): These are attached to the connector ring (see figures 1 and 4). They have small 4-pin military connectors.
Cycling cable: 26-pin military connector located on the left side of SPARO's feedthru ring (see figure 5).

Fig 5 - SPARO on Viper (2001), showing cycling connector that plugs into a feedthru on SPARO's feedthru ring.

From control room, move focus motor towards "in" direction so that SPARO is resting on the stops on its rails. Be careful not to stress any connector, pump-line, etc.
Remove the focus bolt that fastens SPARO to the focus assembly via the aluminum cone (see figures 1 and 4).

Close the valve at the pump in the pump room.
Close the pumped pot VAT valve at the dewar (figure 1). Use the orange-handled torque wrench that has been pre-set to a torque of approximately 5.76 Newton-meters (Nm). When the torque wrench "clicks", you have closed the valve.
Disconnect the conflat connection to the VAT valve, as follows: There is a 90-degree elbow fitting connected to the VAT valve. There is an adapter connected to this elbow fitting. Break the connection between the adapter and the elbow fitting by removing the six screws. You will hear air rushing, as this step will vent the pumped pot line.
Cover both open ports of the vacuum line with plastic bags or blank-off fittings or plastic caps. This step is important because snow and ice in the line can severely inhibit the pump's performance.

Figures 6 - 10 illustrate the procedures used.
Note that you have to disconnect and tape up the snout heater cable before putting SPARO on the cart, in order to avoid damaging this cable (see figure 10).
When lifting SPARO, don't hold on to the foam-covered preamps. Also, don't hold the external He-3 tanks. Instead, to carry SPARO, use (a) the aluminum carrying bar that bolts to the connector ring, (b) the aluminum handles located below the preamps, and (c) the rectangular frame on the underside of SPARO, where it mounts to the telescope. Try not to bump the Helium-3 gauges and valves that run alongside the Helium-3 tanks. These are more delicate than they appear.

larger	Fig 6 - Overhead crane used to install and remove SPARO (2003)
larger	Fig 7 - SPARO being installed to Viper (2003)
larger	Fig 8 - SPARO on the hoist (2001)
larger	Fig 9 - SPARO on its cart (2003)
larger	Fig 10 - Undo and secure this connector before putting SPARO on cart (2003)

Reattach the flow meter assembly
SPARO owns two Alcatel 2015 mechanical pumps. One is white and one is orange. Resume pumping on the pumped pot by (a) hooking up a mechnical pump as shown in figures 11-14, (b) switching on the pump to pump out the line, and (c) opening the VAT valve. Note the pressure on the Capacitance manometer gage. During 2003, it read in the range 1-2 Torr.

larger	Fig 11 - A view of the "flushing fixture" that attaches to SPARO pumped pot port (2003 photo).
larger	Fig 12 - Another view of this "flushing fixture". The use of this fixture allows one to either pump on the pumped pot, or apply back pressure as is typically used for warmup and cooldown. (2003 photo).
larger	Fig 13 - Diagram of the flushing fixture and the reservoir pumping fixture. (Reservoir pumping fixture used for cooldown only.)
larger	Fig 14 - Mechanical pump used to pump on pumped pot, with capacitance manometer gage (2003)

Snow can get into the electrical connectors if they are not covered up somehow.
In the past, we have used thick polyethylene sheeting to cover up the connectors, held in place by silver matellic tape, with pink foam to form a seal between the cable and the polyethylene sheet.

Last Updated Aug. 20, 2003 GN