Description
STS replacement circuit boards are available for direct replacement of damaged boards in the STS 300 Ground Monitoring System. Boards must be specified by voltage: 12 VDC, 24 VDC, 120 VAC or 240 VAC. Some retrofit capability to older STS 300 Series models is possible; contact STS to confirm for your unit.
Choosing the right board
Match the board to the voltage on the nameplate on the front cover of your STS 300, and to whether your system has the deadman option.
| Part number | Voltage | Grounding system | Option |
|---|---|---|---|
| CH-12 | 12 VDC | G12 | None |
| CH-12DM | 12 VDC | G12 | Deadman |
| CH-24 | 24 VDC | G24 | None |
| CH-24DM | 24 VDC | G24 | Deadman |
| CH-120 | 120 VAC | G2 | None |
| CH-120DM | 120 VAC | G2 | Deadman |
| CH-240 | 240 VAC | G4 | None |
| CH-240DM | 240 VAC | G4 | Deadman |
Important: for AC systems, do not connect a 240 VAC power source to a 120 VAC rated board. This opens a non-replaceable safety fuse and disables the unit entirely.
When to replace the board
The STS 300 troubleshooting table lists fault or damage in the controller wiring or PCB as a possible cause of no lights. The maintenance schedule includes checking that the PCB is free from corrosion or water damage and that its mounting screws are properly installed.
Installation
Switch off power and lock out the system first. The board sits inside the enclosure, secured by four corner screws. The clamp cable connects to terminal P2, the integrity ground cable to P3, power to terminals 1 and 2, and the lamp wires to terminals 2, 3 and 4. Full steps are in the circuit board replacement instructions (PDF).
Compatible products
FAQ
Will a new board fit my older STS 300?
Some retrofit capability to older STS 300 Series models is possible. Contact STS with your model number to confirm.
How do I know which voltage I need?
The supply voltage is marked on the nameplate on the front cover. The second part of the model number also shows it: G2 is 120 VAC, G4 is 240 VAC, G12 is 12 VDC and G24 is 24 VDC.
Not sure which part fits your unit? Request a quote with your STS 300 model number and STS will confirm the part.
