⚙️ Balboa M2/M3 Spa Circuit Board — 54122 (Millennium Series, Deluxe/Serial Standard)

OEM-quality replacement circuit board for Balboa M2 and M3 Millennium series spa control systems.

🔌 Product Overview

The Balboa M2/M3 Circuit Board (Part Number 54122) is a genuine Balboa Water Group® replacement PCB for the Millennium 2 (M2) and Millennium 3 (M3) series spa control systems. These high-feature Balboa systems were widely used across many premium spa brands during their production run, including Majestic Spas, Cal Spas, Diamond Spas, and numerous OEM manufacturers.

The 54122 is a uniquely versatile board: it covers both Serial Deluxe and Serial Standard system types within a single PCB — the operating mode is selected by jumper configuration in the field. This means one board serves two distinct M2/M3 configurations, making it a powerful and flexible replacement for the full M2/M3 legacy chip family.

Key standout features include a 30-day battery backup that preserves system settings through power outages, and an optional ORP (Oxidation-Reduction Potential) protection output for advanced water quality monitoring. The board supports a rich set of outputs: 2-speed primary and secondary pump control, blower, circulation pump, ozone/UVC, and flexible lighting options including standard 12V spa light, 120V fiber optic, or an optional 120V 100W circuit.

⚠️ Note: This board does not support mister outputs. If your spa has misters, contact Parts4Tubs to confirm compatibility before ordering.

✨ Key Features

• ✅ Genuine Balboa OEM Board — Manufactured by Balboa Water Group; chip M2/M3R1(x); covers all M2 and M3 Millennium series revisions
• ✅ Dual-Mode Board: Deluxe AND Serial Standard — Single board covers both system types; mode is set by jumper configuration at installation — no need for two separate boards
• ✅ 30-Day Battery Backup — Retains system programming and settings through power interruptions for up to 30 days
• ✅ Optional ORP Protection Output — Supports optional ORP sensor integration for advanced water chemistry monitoring
• ✅ Dual 2-Speed Pump Control — Supports a 2-speed primary pump and a 2-speed secondary pump; both individually voltage-configurable (110V or 220V)
• ✅ Full Accessory Suite — Blower output, circulation pump, ozone/UVC, and lighting outputs all onboard
• ✅ Flexible Lighting Options — Supports standard 12V spa light, 120V fiber optic lighting, or an optional 120V 100W lighting circuit
• ✅ Broad OEM Brand Coverage — One board covers Balboa M2/M3R1(x), Majestic Spas AC100R1(x), Cal Spas CS4000R1(x), Diamond Spas DS100R1(x), and many more legacy chip families
• ✅ Dual-Voltage Support — 110V or 220V operation; compatible transformers: 30270-1 (120V) and 30270-2 (240V)
• ✅ Dual Sensor Compatible — Works with Balboa 30337 combination temperature and hi-limit sensor assembly
• ✅ 1-Year Manufacturer’s Warranty — Backed by Balboa Water Group’s 1-year limited warranty

⚙️ Technical Specifications

Specification	Value
Manufacturer Part Number	54122
Chip ID	M2/M3R1(x) — all revisions (R1A, R1B, R1C, R1D)
Board Model	M2 / M3 (Millennium 2 and Millennium 3 Series)
Board Type	Replacement Main PCB — Deluxe / Serial Standard (jumper-selectable)
Input Voltage	110VAC or 220VAC (dual voltage)
Frequency	60Hz
Pump 1 Output	2-Speed, 110V or 220V
Pump 2 Output	2-Speed, 110V or 220V
Blower Output	Yes
Circulation Pump	Yes
Ozone / UVC Output	Yes
Spa Light Output	12VAC standard; or 120V fiber optic; or optional 120V 100W circuit
Battery Backup	30-day battery backup for settings retention
ORP Protection	Optional ORP output supported
Mister Output	⚠️ Not supported — see note above
Topside Connector	8-pin phone cable (primary); 6-pin phone cable (auxiliary)
Compatible Sensor	30337 dual sensor (combination temp and hi-limit)
Compatible Transformers	30270-1 (120V); 30270-2 (240V)
Board Dimensions	Approx. 8.5 in × 7.125 in (216mm × 181mm)
GFCI Protection	Required — Class A GFCI per NEC Article 680
Warranty	1 year (Balboa Water Group manufacturer’s warranty)

⚠️ Heater output capacity is not published in available sources for this board. Refer to your original system documentation or contact Parts4Tubs with your system part number for heater confirmation.

ℹ️ US VOLTAGE NOTE: This board is dual-voltage (110V/220V). Most US residential hard-wired hot tubs use 220–240V/60Hz. Always verify your spa’s electrical configuration before ordering and configure the board accordingly.

🔗 Compatibility Guide

Primary Chip Numbers Covered

Chip ID	OEM Brand
M2/M3R1(x) (all revisions: R1A, R1B, R1C, R1D)	Balboa native M2/M3
APS100R2(x) / APS100R2A	Balboa APS systems
AC100R1(x) / AC100R1A	Majestic Spas
CS4000R1A / C3000R1C / C3000R1D / CS3000R	Cal Spas
DS100R1C / DS34R2A / DS34R2B / DS4R3C	Diamond Spas
MAJ200R1B / MAJ200R1D	Majestic Spas
MAS300R1F	Master Spas
2000DR1C / 2000DR2B	Legacy Balboa 2000D systems
SEV200F.O. / SEV200FO	Sovereign/SEV systems
M2GAS	Balboa M2 Gas heater variant

ℹ️ This is not a complete list of all covered chips. Many additional legacy chip designations are also covered by the 54122. Contact Parts4Tubs with your exact chip number to confirm compatibility.

Also Listed Under These Numbers

Number	Type
52518	Balboa modern retrofit replacement (see note below)
9710-19	Alternate SKU
610992 / 611313	Legacy alternate numbers
23163	Alternate reference
BAL54122	Distributor prefix variant
33-54122-K	Kit variant

ℹ️ About 52518: Balboa has developed the 52518 Retrofit Kit as the current production successor to the 54122. The 52518 includes the updated board with overlays and is generally more readily available. If you are flexible on the exact replacement, the 52518 may be the better choice. Contact Parts4Tubs to discuss.

Compatible Topside Panels

Part Number	Panel Description
51058	VL801D — Serial Deluxe
51057 / 51057-01	VL701S variant
54128	M2/M3 compatible
54108	M2/M3 compatible
54155 / 54156	M2/M3 compatible
51452	M2/M3 compatible
53189 / 53189-01	VL701S — Serial Standard
51247	M2/M3 compatible (51247-01 discontinued, use 51247)
53811	VL700S
54170	M2/M3 compatible
51216	Auxiliary topside
22174	2-to-1 Y Connector for dual topside configurations

Selected Legacy Boards Replaced

The 54122 replaces a large number of legacy Balboa and OEM boards. Key replacements include:

Part Number	Notes
50862, 50975	Legacy M-series boards
510ER1A, 51408, 51414, 51511	Legacy M-series boards
51545, 51789, 52014, 52025	Legacy boards (some require topside replacement)
520ER1C, 52518	Legacy and current retrofit
961XR1A	Legacy variant
LB104R1B/C/D/E	Leisure Bay LB104 family
SAR200R2A, SS3000R1A	Legacy OEM variants
WS200R1A, ZX2000R2A/B	Legacy OEM variants

⚠️ Some older boards require a new topside panel when replacing with the 54122. Always verify topside compatibility when upgrading from a much older board revision.

⚠️ Always verify compatibility using the chip number on your existing board — not board appearance. Many Balboa boards look identical but have different programming.

🎛️ Board Functions & Controls

Pump Control

Output	Function	Voltage
Pump 1	Primary jet pump — 2-speed	110V or 220V
Pump 2	Secondary jet pump — 2-speed	110V or 220V
Blower	Air blower	Voltage-configurable
Circ Pump	24-hour circulation pump	Voltage-configurable

Heater Control

Feature	Detail
Heater Output Capacity	See manufacturer documentation or contact Parts4Tubs
Sensor Assembly	30337 dual sensor (combo temp and hi-limit)
Freeze Protection	Yes — board activates pump at freeze conditions

Lighting

Option	Specification
Standard Spa Light	12VAC
Fiber Optic Lighting	120VAC option
Optional Circuit	120V / 100W optional output

Special Functions

Feature	Detail
Battery Backup	30-day retention of system settings through power loss
ORP Output	Optional — for ORP water quality monitoring
System Type	Deluxe OR Serial Standard — jumper-selected at installation
Misters	⚠️ NOT supported by this board

🔧 Installation Requirements

⚠️ IMPORTANT: Installation must be carried out by a licensed electrician in compliance with NEC (National Electrical Code) Article 680 and all applicable local codes.

Pre-Installation Checklist

• [ ] Confirm chip number on your existing board — locate white sticker on logic chip near board center
• [ ] Confirm chip number matches M2/M3R1(x) or one of the supported OEM chips listed above
• [ ] Note your system type (Deluxe or Serial Standard) — needed to set the correct jumper on the new board
• [ ] Disconnect all power at the breaker and disconnect box before starting
• [ ] Photograph all wiring, jumper positions, and DIP switch settings before removing old board
• [ ] Allow capacitors to discharge — wait at least 5 minutes after power-off
• [ ] Note transformer being used: 30270-1 (120V) or 30270-2 (240V) — confirm voltage match

Electrical Requirements

Requirement	Specification
Supply Voltage	110VAC or 220VAC / 60Hz
GFCI Protection	Class A GFCI required — per NEC Article 680
Ground Connection	Equipment grounding and bonding per NEC Article 680
Dedicated Circuit	Required
Disconnect Box	Required within line of sight of spa; at least 5 feet from spa walls per NEC

💡 System type (Deluxe vs. Serial Standard) and other operating options are set by jumper configuration on the board. Copy all jumper positions from your original board before removal, or refer to the wiring diagram inside your spa pack lid.

⚠️ Safety Warnings

Electrical Safety

• ⚠️ ALWAYS disconnect all power at the breaker and disconnect box before any work
• ⚠️ Installation by a licensed electrician only — required by NEC and most local codes
• ⚠️ Verify correct supply voltage (110V or 220V) before connecting — use the appropriate transformer (30270-1 or 30270-2)
• ⚠️ Class A GFCI protection is mandatory per NEC Article 680
• ⚠️ Disconnect box must be within line of sight of the spa and at least 5 feet from spa walls per NEC
• ⚠️ Equipment grounding and bonding are mandatory per NEC Article 680
• ⚠️ Setting jumpers incorrectly can cause abnormal system behavior or component damage

Special Order Safety

• ⚠️ Verify chip number BEFORE ordering — this item is non-returnable once ordered
• ⚠️ Do not order based on board appearance — many boards look identical but have different software
• ⚠️ If your spa has mister outputs, contact Parts4Tubs before ordering — the 54122 does not support misters

Water & Electrical Safety

• ⚠️ No water ingress into the control box at any time
• ⚠️ Inspect all seals and gaskets during installation
• ⚠️ Never touch electrical components with wet hands

🔍 Error Codes & Troubleshooting

Code	Meaning	Basic Action
OH / OHS	Spa overheat — water temp limit reached (110°F / 43.3°C)	Allow spa to cool; check sensors and water flow
OHH / HH	Heater overheat — extreme temp at element	Power down; check flow, filters, sensor connections
HFL / HL	Heater flow low — insufficient water through heater	Check water level, dirty filter, closed jets/valves, pump prime
LF / LOW FLOW	Verified low flow — heater disabled	Resolve flow issue; press any button to reset
dr / dry	Dry fire detected	Check water level and pump prime
FL / FLO	Flow switch fault	Check water level, filter, flow switch wiring
SnS / Sn	Sensors out of sync — >2°F difference between A and B	Monitor 1 hour; if flashing: contact technician
SnA / SA	Sensor A failure	Check 30337 sensor connection; replace if faulty
Snb / Sb	Sensor B failure	Check 30337 sensor connection; replace if faulty
ICE / IC	Freeze condition	Board auto-activates pump to protect plumbing
No COM	Topside communication error	Check 8-pin phone cable connections at both ends

🎯 Ideal Applications

Application	Suitability	Notes
♨️ Balboa M2 Millennium series spa	✅ Direct replacement	Confirm chip number M2/M3R1(x)
♨️ Balboa M3 Millennium series spa	✅ Direct replacement	Confirm chip number M2/M3R1(x)
♨️ Majestic Spas (chip AC100R1)	✅ Compatible	Broad AC100R1(x) family coverage
♨️ Cal Spas (chip CS4000R1 / C3000R)	✅ Compatible	Multiple Cal Spas chip variants covered
♨️ Diamond Spas (chip DS100R1)	✅ Compatible	DS100R1C and DS34/DS4 families
♨️ Spa with mister output	⚠️ Verify first	54122 does NOT support misters

❓ Frequently Asked Questions

Q: How do I verify this is the correct board for my spa? A: Find the white sticker on the logic chip near the center of your existing circuit board — this shows your chip number. If it matches M2/M3R1(x) (any revision), or any of the supported OEM chip numbers listed above, the 54122 is your replacement. Do not identify the board by appearance or the 5-digit number printed on the board edge.

Q: What does “Deluxe and Serial Standard” mean for this board? A: The 54122 covers both M2/M3 Serial Deluxe and Serial Standard system types with a single board. The operating mode is configured by jumper settings at installation. Copy your original board’s jumper positions, or refer to the wiring schematic on the back of your spa pack cover.

Q: Is this board discontinued? A: The 54122 is a legacy special order item — still available with a 2–5 business day lead time, but no longer a stocked production board. Balboa’s 52518 retrofit kit is the current-production replacement. Contact Parts4Tubs to discuss which option is best for your situation.

Q: My spa has misters — will this board work? A: No. The 54122 does not support mister outputs. Contact Parts4Tubs to identify the correct board for your spa if misters are present.

Q: What voltage does this board use? A: The 54122 supports both 110VAC and 220VAC (60Hz). The correct voltage is set by which transformer is installed: 30270-1 for 120V service, or 30270-2 for 240V service. Most US hard-wired residential hot tubs use 220–240V. Always verify before ordering.

Q: Can I cancel or return this order? A: No. The 54122 is a special order — it cannot be returned or canceled once the order is placed. Please verify your chip number carefully before purchasing. Contact Parts4Tubs if you are unsure.

Q: What warranty is included? A: Balboa Water Group’s standard 1-year limited manufacturer’s warranty. Circuit boards cannot be returned after installation except for verified warranty defects. Improper installation or incorrect voltage configuration voids the warranty.

Q: What if my spa needs the 52518 instead? A: The 52518 is Balboa’s current retrofit kit for M2/M3 systems and includes updated overlays and jumper documentation. Contact Parts4Tubs to compare options for your specific system.

🏆 Why Choose the Balboa M2/M3 54122

• ✅ Genuine Balboa OEM Board — Manufactured by Balboa Water Group to original production standards
• ✅ Widest OEM Coverage Available — One board covers Balboa M2/M3, Majestic, Cal Spas, Diamond Spas, and dozens of other legacy chip families
• ✅ Dual-Mode Flexibility — Serial Deluxe AND Serial Standard in a single board — jumper-configurable on site
• ✅ 30-Day Battery Backup — Preserves programming through power outages — a feature not common on standard replacement boards
• ✅ Optional ORP Support — Advanced water quality monitoring capability built in
• ✅ Rich Output Set — Dual 2-speed pumps, blower, circ pump, ozone/UVC, and flexible lighting — all in one board

🤝 Why Buy from Parts4Tubs

• ✅ US-based company with knowledgeable local support
• ✅ Fast US shipping (special order items ship within 2–5 business days)
• ✅ Expert technical advice from spa specialists who know Balboa M-series systems
• ✅ Competitive pricing on genuine OEM parts
• ✅ Full manufacturer warranty support
• ✅ Help identifying the correct board — contact us with your chip number before ordering
• ✅ Can advise on 52518 retrofit kit as a modern alternative

✨ Summary

The Balboa M2/M3 Circuit Board (54122) is a genuine OEM replacement PCB for Balboa Millennium 2 and Millennium 3 series spa control systems, covering an exceptionally broad range of OEM chip families including Majestic, Cal Spas, and Diamond Spas. It features 30-day battery backup, optional ORP support, dual 2-speed pump control, blower, circ pump, ozone, and flexible lighting — configurable for both Serial Deluxe and Serial Standard system types by jumper. As a special order item, it is non-returnable once ordered. Always verify your chip number before purchasing, and contact Parts4Tubs if you would like to explore the 52518 retrofit kit as a modern alternative.

Parts4Tubs is proud to be a Balboa Authorized Online Seller - make sure you only buy genuine Balboa parts from trusted sources.

Finding and identifying a replacement Hot Tub Circuit Board (PCB)

If you are looking to replace a failed PCB on your Hot Tub’s spa pack, then quite often identifying the part that you need can be the hardest thing.

Firstly, you are looking for a model number on the actual circuit board itself. Having the model or serial of your hot tub is not going to help at this point, you need to find the number on the PCB itself.

Now, with certain brands of PCB, the number of the replacement PCB that you need is not going to match identically the one you are replacing. Why is that I hear you ask?

Well, normally, it is an updated version. This means that it might have updated firmware on the PCB or be a later revision. Normally, this means that the part number would be slightly different. This is usually indicated with a “12345678 -x” at the end of that part number where x indicated a firmware revision.

In some cases, there will be some following letters on the part number of the circuit board, “12345678 -x MAS” this can indicate that the PCB was used for an OEM meaning it was produced for a certain hot tub manufacturer and the letters identify the manufacturer.

This means if you source an original PCB, it will not have the letters, but will in most cases work just fine.

It can be confusing I know!

What if you can’t find a model number?

If you can’t find a model number on the PCB itself, then you need to look for a model number on the spa pack. Normally, there is a sticker on the outside of the spa pack that tells you the current ratings and input voltages etc and this will have a model number.

In general, most spa packs in the USA are manufactured by Balboa, Hydro-Quip, ACC or Gecko. I know I am generalising here, but if you have a spa pack that has the brand of your hot tub on, it will be an OEM so the key is identifying who made the original box.

From there, you can normally find an original PCB that you will be able to switch out.

For example, the Balboa VS (value series) is a very popular spa pack that has been used by multiple hot tub manufacturers under their own brand names. Whatever they have called it, strip it back and it is still a Balboa VS.

Visual Inspection

One of the most important things you can do when you are looking for a replacement is to visually inspect the PCB that you have versus the picture online of the replacement you are considering. They need to look the same even if there are the differences in firmware revisions or OEM part numbers, you should be visually replacing a PCB that looks like the one you have.

Configuring a replacement Hot Tub Circuit Board (PCB)

When you get a new PCB, you are more than likely going to need to configure it. Most PCBs have a number of different modes and setups that the can operate in. For this, you will need to manual or spec sheet to guide you.

For things like DIP switches, most of the time you can copy the settings from your original circuit board. You are looking for things like setting the voltage as a lot of PCBs can be configured to run on both 115V and 230V.

You may need to move jumpers or even wires to configure voltages – the key here is that you read the schematic and don’t expect the PCB to just work out of the box – it usually doesn’t.

Troubleshooting a Hot Tub Circuit Board (PCB)

Here are some common things you will see when you replace a PCB on a hot tub.

You press the buttons on the topside control and they don’t control the right parts (pumps or blower etc) – this is a mode configuration thing and you will either need to change some DIP switches on the PCB or an internal or low level programming mode on the topside control. Check the manual for how to do this.

You turn on the hot tub and it trips the breaker – it is not common for a new PCB to fail out of the box (I have not seen one yet!) However, a common mistake is that the voltage has not been set correctly. If it is set for 115V and then you try and turn it on, the current draw will be a lot more (twice) than expected and the breaker will trip.

To check this, unplug all of your kit – heater, pumps, blower and then turn on the PCB. If it trips with nothing plugged in, usually the voltage is incorrectly set and what is happening is that live current is being sent to the ground – because you have 4 wires into the PCB rather than 3. Current on the ground loop causes the trip. Check the settings to make sure it is configures for 230V.

It might not trip until you physically turn on a pump or a blower. As mentioned, if the pack is set to 115V and your pump is meant for 230V, it will draw twice the current at half the voltage and trip your breaker. Check the manual for info on how to set the voltage.