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Balboa 51859 Circuit Board MIL75R1(x) Alt Replacement, Millennium Spas

Balboa 51859 Circuit Board MIL75R1(x) Alt Replacement, Millennium Spas
  • Manufactured by: Balboa Water Group, Inc.
  • Part Number: 51859
  • Chip Number: MIL75R1(x)


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Item Number: 22-4771

  • Description
  • Details
  • Reviews

The Balboa 51859 MIL75R1(x) circuit board is discontinued but we have options.

Option 1: Get your circuit board repaired.  Please contact us before sending items in for repair.

Option 2: Contact us to inquire about a new retro-fit system control box replacement.

The Balboa 51859 MIL75R1(x) circuit boards are also found in hot tubs made by Millennium Spas and possibly others.
Cross Reference Verification
Serial Numbers:
  • 51859
  • BAL51859

Chip Numbers:
  • MIL75R1A
  • MIL75R1B
  • MIL75R1C
  • MIL75R1D
  • MIL75R1E
  • MIL75R1F
Additional Cross Ref., Compatibility & Installation
ATTENTION: The original topside keypad's backlighting and connector are no longer supported.
The keypad buttons will still function but it will not have backlighting.
Tip: When replacing a hot tub circuit board, testing the heater and replacing it (if bad), is recommended before installing or applying voltage on a new circuit board.
Note: A continuity test is not a sufficient heater test. Contact us by phone for more details on testing a heater.

Tip: Burned circuit boards or burned heater relays are often due to a loose electrical connection or a bad heater or both.
If all connections are tight and if the heater is good then the heater relays are probably old and worn out.
If a burned relay was powering a pump and all electrical connections are tight then the relay is probably old and worn out or the pump might be bad or going bad or all three.
Replacing the heater and/or pump with a new one is recommended if any of those scenarios apply.

Unsure of what something on this page means?

Please contact us so we can better assist you.


  • Manufactured by: Balboa Water Group, Inc.
  • Part Number: 51859
  • Part Number: MIL75R1(x)
  • Item Number: 22-4771


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