Part identifiers and kit contents Control board OEM numbers: 420020007S and 461105 Switch membrane pad OEM numbers: 420020029Z and 472610Z Kit includes the replacement control board and the matching switch membrane pad for compatible pool and spa heaters Compatibility Compatible with MasterTemp 200, 250, 300, and 400 control boards Compatible with the following models: MaxETherm SR200NA, SR333NA, SE400NA, SE333HD, and SR400HD control boards Compatible with NA and LP series pool and spa heater electrical systems Not compatible with MasterTemp 200hd Key benefits and why this product is needed Restores heater operation when the existing control board fails to start the heater or the display is unlit Improves water heating response when slow heating is caused by a malfunctioning control board Upgraded internal components increase reliability and reduce the chance of repeat failures compared with older boards What makes this control board kit stand out Upgraded solidstate capacitors and power chips for improved durability under load Improved optocoupler module for better signal isolation and stability Regulated power module to provide steadier voltage to control circuits and reduce operational glitches Designed as a direct replacement for the listed OEM numbers to simplify installation and minimize fitment issues Function and performance Replaces the original control board to restore or improve heater control functions, display operation, and ignition sequencing Addresses common failure symptoms such as no power to the heater, unresponsive controls, and slow or inconsistent water heating Enhancements yield quicker control responses and more reliable operation during normal use Practical attributes Form factor and connector layout designed to match original equipment for direct replacement in compatible systems Electrical components upgraded to solidstate designs for longer service life under typical heater operating conditions Intended specifically for electrical control duties; does not alter plumbing or gas components Use scenarios a failed control board after the heater will not power on and the display remains blank Upgrade a heater control board showing intermittent faults or slow response to control input, to restore consistent temperature control Install as part of a where the membrane pad is cracked or worn and causing misread or stuck button inputs Installation notes and compatibility warnings Designed to be a dropin replacement for the listed OEM numbers and compatible models; verify OEM numbers on the existing board before installation Not suitable for models outside the listed compatibility, including MasterTemp 200hd Professional installation is recommended if you are not experienced with electrical repairs on pool and spa heaters This control board kit provides a direct replacement option with upgraded components to help restore reliable operation and consistent heating performance in compatible pool and spa heater systems.