Secondary Power Supply

The secondary power supply (SPS) is a board that supplies regulated +5VDC and -8VDC. It also has the circuitry to control the standard lamp (SL), mercury lamp (HG) temperature monitoring, stepper motor power and high voltage power (HV).
Note - Part of the SL, HG, and HV circuitry lives on the heatsink.
Note2 - The SPS board also includes the rate meter circuitry, however this is not used and usually shorted out to by pass it.

SPS board assembly

SPS board assembly

Secondary Power Supply Board Assembly

SPS board schematic - Temperature circuit

SPS board schematic - Temperature circuit

Secondary Power Supply Schematic - Temperature monitoring circuit

SPS board - HG, Stepper motor and voltage regulator

SPS board - HG, Stepper motor and voltage regulator

Secondary Power Supply Schematic - Mercury bulb, Stepper motor, and +5V/-8V Regulator circuit

SPS board - HV and SL circuit

SPS board - HV and SL circuit

Secondary Power Supply Schematic - High Voltage and Standard Lamp circuit

SPS board potentiometer control

SPS board potentiometer control

Secondary Power Supply - Potentiometer Control

SPS board V1 Top

SPS board V1 Top

SPS board V1 Top

SPS board V1 Bottom

SPS board V1 Bottom

SPS board V1 Bottom

SPS board V2 Top

SPS board V2 Top

SPS board V2 Top

SPS board V2 Bottom

SPS board V2 Bottom

SPS board V1 Bottom

Note: the V2 board is a version 2 board is in development board done by Environment and Climate Change Canada.

New & Old Temperature Circuit

To identify if the SPS board is using the new or old temperature circuit, you will need to locate the following

ResistorOld Temperature CircuitNew Temperature Circuit
R601, R604, R60511MΩ825KΩ
R602, R606, R6071.6MΩ3MΩ