Hot Tub Models This Circuit Board Was Used In

• Sundance® Spas 850 Series (1997-2000) with PermaClear circulation pump, 1 or 2 pump systems (EPROM Rev 1.28GX+):contentReference[oaicite:1]{index=1}
• Sundance® Spas NT (2001-2005) 850 NT models, single-speed air blower only:contentReference[oaicite:2]{index=2}
• Not compatible with Maxxus® models:contentReference[oaicite:3]{index=3}
• Used in Jacuzzi® J-300 / J-350 / J-355 / J-365 / J-370 / J-375 (2002-2006) configured for one 2-speed jet pump + one 1-speed jet pump:contentReference[oaicite:4]{index=4}

Replaces the Following Circuit Boards

• 6600-028
• 6600-056
• 6600-092
• 6600-180 (via updated 6600-730 variant)
• 6600-017, 6600-018, 6600-023 same PCB with different EPROM versions:contentReference[oaicite:5]{index=5}

Uses the Following Accessories

• PermaClear circulation pump (factory config)
• EPROM Rev 1.28GX+ (included on replacement boards):contentReference[oaicite:6]{index=6}
• Compatible keypads/topside controls for Sundance 850 and Jacuzzi J-300 series:contentReference[oaicite:7]{index=7}

Additional Important Installation Notes

Replacement circuit boards are discontinued, so customers receive the updated 6600-730 model when ordering:contentReference[oaicite:8]{index=8}.

Ensure jumper settings (e.g. JP9) and connectors match the original board photos and careful mapping are strongly recommended to retain diagnostic/trouble log functionality:contentReference[oaicite:9]{index=9}.

If 850 Series (1999-2005) or if Pump 1 is 2-speed, use 6600-730 as a replacement.

If 880 Series (2005-2010) or if Pump 1 is 1-speed, use 6600-728 as a replacement.

Not for use with models requiring 6600-728, 6600-390, or 6600-392 boards. Always confirm system pump configuration (e.g. 2-speed vs single-speed) before installation:contentReference[oaicite:10]{index=10}.