The FootLocker Interface Chassis, FLIC, AC Input Module is a plug in module that accepts the input AC and allows it to flow to the CCD Controller. Also, the input module contains the over temperature relay, RY1. As shown to the left, the 110VAC enters via an AC filter module and a 5A S/B fuse. The AC power is wired to a normally closed contact of the relay RY1-1. The AC is wired from RY1-9 to TB1-10, 11, &12. This is then wired to two AC receptacles mounted on the back panel of the AC input module. This is where the CCD Controller is plugged into. This circuit will remain powered unless the temperature in the footlocker rises above 85° F. If the coolant system were to fail or the CCD Controller software were to hang, the electronics will be protected from overheating by the action of the thermostat closing and supplying power to pull in RY1. When activated, the relay do three things: 1.) disconnect the AC power from the CCD Controller, 2.) turns on the Sonalert that is mounted on the roof of the HIRES Instrument Enclosure, and 3.) close a set of contacts that parallel the thermostat so that the relay will not reset until the Reset Pushbutton is pushed. This last action should only be attempted after the footlocker has been opened and the cause of the problem determined. If the Reset button is pushed the circuit will not reset until the thermostat cools down below about 67°. The Reset Button is wired in series with the relay coil and by activating the button the relay will power off.
IT IS VITALLY IMPORTANT TO FIND AND REPAIR THE CAUSE OF AN OVER-TEMPERATURE EVENT. The safety of the electronics in the electronics footlocker and the in dewar electronics enclosure must not be compromised.

 

---

Terry Rickets' original write up:
(Some words are stricken through to help to keep the reader from confusing things with the new upgrades system)

The CCD Controller chassis will be producing about 100W of heat while running. This heat must be removed so that the instrument will not be impacted by the heat. At the same time the electronics of the Controller need to be kept above 0° C to operate reliably. We have chosen to operate the chassis at 5° C. An insulated box surrounds the chassis to contain the heat. Within the box is a radiator to remove the heat. The telescope will provide coolant that can be pumped through the radiator to cool the chassis. A fan is provided to force the warmed air to pass through the radiator for cooling.
The fan (shown in the center of the drawing) is controlled by a Solid State Relay. This relay is controlled by a digital output (Dout 2 at pin A7) from the Utility board shown on the left. The temperature of the chassis is measured directly on the Utility board by a temperature sensor.
It is possible that the software might become deranged or the coolant not be working properly. In either of these conditions the temperature inside the insulated box could exceed the ratings of the components. An over-temperature protection circuit has been provided for such an emergency. The power for the box enters via a noise filter socket on the entry panel (see bottom right of drawing). It is routed via a normally closed contact of a relay to the rest of the electronics. The coil of the relay is connected to the power through normally open thermostat. This thermostat will close at 80° F. Thus if the temperature inside the box exceeds 80° F the relay will engage and remove power to the electronics. One of the relay contacts is used to parallel the thermostat forcing the power to stay off until the user opens the box, inspects for the cause of the problem, and pushes the reset button to restore power. Another contact of the relay routes 110VAC through the conduit with the optical fibers to the roof of the Instrument Enclosure. In a breakout box on the root the 110VAC will power a Sonalert to warn the user that the instrument has shut down because of temperature problems.