{"product_id":"liftmaster-k21-36793","title":"LiftMaster K21-36793 Control Transformer — 208\/230\/460V, 20VA","description":"\u003cp\u003e\u003cstrong\u003eThe LiftMaster K21-36793 is the 20VA control-transformer service reference listed for documented LiftMaster commercial-door operator electrical boxes with 208\/230\/460V supply configurations. It belongs to the operator’s control-power circuit and must be selected using the exact model, installed electrical arrangement and transformer label. The multiple listed supply voltages do not mean that the transformer automatically selects a voltage or that replacing it converts the complete operator to another supply. Verify the specified connections and the remaining equipment ratings before ordering.\u003c\/strong\u003e\u003c\/p\u003e\u003ch2\u003eCompatibility — Models, Versions and Exclusions\u003c\/h2\u003e\u003ctable\u003e\n\u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eModel or selection point\u003c\/th\u003e\n\u003cth\u003eCompatibility requirement\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eDocumented T \/ GT \/ APT \/ SD \/ GSD \/ GH arrangements\u003c\/td\u003e\n\u003ctd\u003eMatch the specific electrical-box drawing and supply configuration.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e120\/240V transformer arrangements\u003c\/td\u003e\n\u003ctd\u003eK21-14182 is separately identified; do not substitute by appearance.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e575V arrangements\u003c\/td\u003e\n\u003ctd\u003eK21-35077 is separately identified for the documented configuration.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMotor supply or horsepower upgrade\u003c\/td\u003e\n\u003ctd\u003eThis control transformer does not establish a motor or whole-operator conversion.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMAXUM and other newer platforms\u003c\/td\u003e\n\u003ctd\u003eUse their own parts documentation; no automatic Logic 5 interchangeability is established.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\u003ch2\u003eMatch the Electrical Configuration Before Selecting the Transformer\u003c\/h2\u003e\u003cp\u003eA commercial operator family can be offered with multiple electrical configurations. Record the complete operator nameplate and transformer label, and inspect the actual wiring diagram inside the equipment. A model name without its supply details is insufficient for selecting a power component. Do not infer the required secondary connections from the 20VA rating or from the voltage used by a nearby accessory.\u003c\/p\u003e\u003cp\u003eHave qualified personnel diagnose the incoming supply, control wiring and connected load before replacing the transformer. A shorted circuit or excessive load can remain after a new part is installed. The 20VA rating describes the transformer’s apparent-power capacity; it is not a motor horsepower rating or permission to add arbitrary accessories to the control circuit.\u003c\/p\u003e\u003ch2\u003eSpecifications and Product Identification\u003c\/h2\u003e\u003ctable\u003e\n\u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eSpecification\u003c\/th\u003e\n\u003cth\u003eDetails\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003ePart number\u003c\/td\u003e\n\u003ctd\u003eK21-36793\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eComponent\u003c\/td\u003e\n\u003ctd\u003eControl transformer\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eManufacturer listed supply configurations\u003c\/td\u003e\n\u003ctd\u003e208\/230\/460V\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePublished rating\u003c\/td\u003e\n\u003ctd\u003e20VA\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDocumented platform\u003c\/td\u003e\n\u003ctd\u003eApplicable Logic 5 commercial-door electrical boxes\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSelection basis\u003c\/td\u003e\n\u003ctd\u003eExact model, transformer label and wiring diagram\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\u003ch2\u003eBefore Ordering\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eRecord the full model, supply voltage and complete transformer markings.\u003c\/li\u003e\n\u003cli\u003eFind K21-36793 in the applicable electrical-box parts drawing.\u003c\/li\u003e\n\u003cli\u003eConfirm the specified primary and secondary connections with the exact diagram.\u003c\/li\u003e\n\u003cli\u003eInspect the control load, protective components and wiring for the cause of failure.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003ePackage Contents and Separate Requirements\u003c\/h2\u003e\u003cp\u003eThis offer identifies the control transformer. A logic board, motor, contactor, fuse set, wiring harness and complete electrical box are not promised as included. Confirm the current package for mounting or connection pieces and retain only hardware approved for reuse. Other parts shown in the same electrical-box illustration remain separate service items unless expressly included in the supplier’s offer.\u003c\/p\u003e\u003ch2 class=\"safety-warning\"\u003eSafety Warnings — Read Before Installation or Service\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eWARNING: Commercial-door electrical boxes contain hazardous supply voltage. Transformer diagnosis, connection and replacement require qualified electrical personnel.\u003c\/li\u003e\n\u003cli\u003eDisconnect and secure all applicable power before service, and secure the door against unexpected movement according to the operator instructions.\u003c\/li\u003e\n\u003cli\u003eDo not energize an unverified connection, improvise voltage taps or treat the transformer as a whole-operator voltage-conversion kit. Preserve grounding and protective devices.\u003c\/li\u003e\n\u003cli\u003eRestore covers and verify control operation, travel, reversal and required monitored protection before the door returns to normal use.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eRelated Products and Important Differences\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/garage-doorparts.com\/products\/liftmaster-photocell-kit-indoor-only-for-30-wide-openings\"\u003eCPS-U monitored commercial photo eyes\u003c\/a\u003e — a separate protection component for approved operators and environments; not supplied with this mechanical accessory.\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/garage-doorparts.com\/products\/liftmaster-extended-duty-trolley-operator\"\u003eTDC12X1BMC MAXUM trolley operator\u003c\/a\u003e — a complete-operator comparison; verify accessory selection against its own documentation.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\u003ch3\u003eDoes this transformer automatically switch among 208, 230 and 460 volts?\u003c\/h3\u003e\u003cp\u003eDo not assume automatic selection. Follow the specified connections for the actual supply and transformer label.\u003c\/p\u003e\u003ch3\u003eIs 20VA a motor power rating?\u003c\/h3\u003e\u003cp\u003eNo. It is the transformer’s apparent-power rating for its specified control-power role.\u003c\/p\u003e\u003ch3\u003eCan it replace the separately listed 575V transformer?\u003c\/h3\u003e\u003cp\u003eNo interchangeability is established. Use the service reference specified for the equipment’s actual electrical configuration.\u003c\/p\u003e\u003ch3\u003eWill a new transformer fix a shorted control circuit?\u003c\/h3\u003e\u003cp\u003eNo. The connected circuit and reason for failure must be diagnosed and corrected separately.\u003c\/p\u003e\u003ch2\u003eNeed Help Confirming the Right Product?\u003c\/h2\u003e\u003cp\u003e\u003ca href=\"https:\/\/garage-doorparts.com\/pages\/contact\"\u003eContact Garage-DoorParts.com before ordering\u003c\/a\u003e. Send the full equipment model, readable part labels and photographs of the installed assembly. Include the dimensions, electrical configuration or accessory details relevant to your project so the listing can be checked against the actual installation.\u003c\/p\u003e","brand":"Controlled products","offers":[{"title":"Default Title","offer_id":60655785869598,"sku":"K21-36793","price":48.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0978\/2781\/5710\/files\/k21-36793.png?v=1793139978","url":"https:\/\/garage-doorparts.com\/products\/liftmaster-k21-36793","provider":"garage-doorparts.com","version":"1.0","type":"link"}