Aftermarket Asco® 300 Series
Controller Replacement

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Buy Factory Direct: $895

Product Summary

Our new aftermarket ASCO 300 Series Group 1 controller is the highest quality and most cost-effective replacement option for the ASCO 300 Series transfer switch controllers K473670-002 (208V), K473670-003 (240V), K473670-006 (480V), and K473670-008 (220V). Our aftermarket controller supports all of the features of the original ASCO controller and much more. Diagnostic LEDs have been added to help in system troubleshooting. We have integrated a fail-safe feature that protects the controller from damage, even in the event that the transfer switch mechanism is stuck or jammed and cannot move. This is a major cause of failure on the OEM original.

Three phase voltage sensing is all solid-state, eliminating the need for voltage-sensing transformers. Improved surge and lightning protection combined with heavy-duty power transformers and a high-efficiency switching power supply work together for enhanced reliability. Feature selection is done with plainly-marked DIP switches. Connection to the communications port has been simplified by eliminating the need for the ASCO 72A Communications Module and implementing a standard RS-485 port. The ASCObus II communications protocol is supported, as well as the local and remote annunciators. The controller PCB assembly mounts directly into the original tray using the original hardware and cover.


  • Exact drop-in replacement for the ASCO 300 Series Group 1 controller PC Board
  • Replacements available for the K473670-002 (208V), K473670-003 (240V), K473670-006 (480V), and K473670-008 (220V) controllers
  • On-board diagnostic LEDs to expedite system troubleshooting
  • Our fail-safe design prevents controller damage if transfer switch contacts fail to move
  • Improved surge and lightning protection
  • Solid-state voltage sensing -- not voltage sensing transformers that can deteriorate over time
  • Interchangeable heavy-duty power transformers
  • High-efficiency switching power supply
  • Simplified DIP-switch feature selection
  • Standard RS-485 full duplex communications port with screw terminal connections
  • ASCObus II communications protocol supported
  • ASCO local and remote annunciators supported
  • ASCO 72A Communications Module is not needed
  • Uses your existing ASCO cover, tray and hardware

Manuals and Downloads

Flight Systems' manufactured products are made in the USA