X937403-006 - Model 1749 90W AC Adapter Charger for Surface Dock 1661 PD9-00003

Genuine OEM Model 1749 external power adapter for the Surface Dock Model 1661. This 90W supply delivers 15V DC at 6A through a three-contact 7.4mm barrel connector with a center sense pin. It is designed to power the dock and provide up to 60W of pass-through charging to a compatible computer connected through the dock's fixed Surface Connect cable.

Technical Specifications

• Primary Part Number: X937403-006
• Product Type: Genuine OEM 90W 15V 6A barrel-tip AC adapter charger
• Adapter Model: 1749
• Alternate OEM Part Number: X937403-002
• Supplier Model: PA-1900-38MX
• Maximum Output Power: 90W
• DC Output Voltage: 15V DC
• DC Output Current: 6.0A
• Dock Pass-Through Charging: Up to 60W through the compatible dock
• AC Input Voltage: 100-240V AC
• AC Input Current: 1.2A
• Input Frequency: 50/60Hz
• AC Inlet: IEC 60320 C8 two-pin inlet
• Required AC Cord Connector: IEC 60320 C7 figure-8 connector
• DC Output Cable: Permanently attached
• DC Connector Type: Three-contact coaxial barrel plug with center sense pin
• Barrel Outside Diameter: 7.4mm
• Barrel Inside Diameter: 5.0mm nominal
• Center Sense Pin Diameter: Approximately 0.5mm; some replacement-tip references round this measurement to 0.6mm
• OEM Exposed-Barrel / Insertion Length: Not authoritatively documented; compare the stock plug with calipers when length is critical
• Load Polarity: Inner annular contact positive and outer sleeve negative
• Observed Center Signal Contact: Separate low-voltage contact likely used for power-good or adapter-sense signaling; it does not carry the 15V load
• Efficiency Level: VI
• Electrical Protection Class: Class II double-insulated design
• Intended Environment: Indoor use at elevations below 2000m as indicated on the label
• Included: One Model 1749 AC adapter; includes power cable - not shown in photos. 

Interchangeable / Replacement Part Numbers

1749, PA-1900-38MX, X937403-002, X937403-006

Hyphenless search forms X937403002, X937403006, and PA190038MX refer to the same identifiers and are not separate part numbers.

Related Docking Station

Need the complete docking station? View the PD9-00003 Model 1661 Surface Dock Docking Station, available separately. This dock uses the Model 1749 90W power adapter with a 15V DC 6A output.

• Dock Item Number: PD9-00003
• Dock Model: 1661
• Required Power Adapter: Model 1749 with 90W output rated at 15V DC and 6A

✅ Confirmed Compatibility

This adapter connects to the round DC input on Surface Dock Model 1661. The computer lists below identify systems supported through the dock's fixed Surface Connect cable; the barrel connector does not plug directly into a computer. Confirm the dock model and its DC input before ordering.

✔️ Direct Dock Compatibility: Surface Dock Model 1661
✔️ Verified Dock Production / Package References: PD9-00003, PD9-00004, PF3-00005, PF3-00006, PF3-00009, PF3-00012
✔️ Surface Pro Models Through Model 1661 Dock: Surface Pro 3, Surface Pro 4, Surface Pro 5th Gen, Surface Pro 6, Surface Pro 7, Surface Pro 7+, Surface Pro 8, Surface Pro 9 all models, Surface Pro 10 for Business, Surface Pro 11th Edition, Surface Pro 12th Edition, Surface Pro X
✔️ Surface Laptop Models Through Model 1661 Dock: Surface Laptop 1st Gen, Surface Laptop 2, Surface Laptop 3 all models, Surface Laptop 4 all models, Surface Laptop 5 all models, Surface Laptop 6 for Business, Surface Laptop 7th Edition, Surface Laptop 8th Edition, Surface Laptop Go, Surface Laptop Go 2, Surface Laptop Go 3, Surface Laptop Studio, Surface Laptop Studio 2
✔️ Surface Book Models Through Model 1661 Dock: Surface Book all first-generation models, Surface Book 2 all models
✔️ Surface Go Models Through Model 1661 Dock: Surface Go, Surface Go 2, Surface Go 3, Surface Go 4

☑️ Key Features

☑️ Genuine OEM Model 1749 power adapter for Surface Dock Model 1661
☑️ Full 90W output rated at 15V DC and 6.0A
☑️ Provides up to 60W of pass-through charging through the compatible dock
☑️ Three-contact 7.4mm by 5.0mm barrel connector with a dedicated center sense pin
☑️ Inner annular positive contact and outer negative sleeve match the original dock power input
☑️ Cross-references both verified X937403 OEM part-number revisions and the PA-1900-38MX supplier model
☑️ Universal 100-240V AC input supports compatible electrical regions with the correct C7 wall cord
☑️ Detachable figure-8 AC wall cord can be replaced for the destination region
☑️ Similar-looking adapters with different voltage, current, contact layout, or center-pin signaling are excluded from the interchangeable list

⚙️ Fit Notes

• Match Model 1749, 15V DC, 6.0A, 90W, and the complete three-contact connector before installation.
• A 7.4mm by 5.0mm barrel measurement alone does not establish compatibility. The center power-good / sense pin and correct contact wiring are also required.
• The small center pin is a separate low-voltage signal contact observed to behave like a power-good or adapter-sense connection. The inner annular barrel contact carries positive 15V power, and the outer sleeve is negative.
• No authoritative OEM drawing for the molded stock plug's exposed-barrel or insertion length was located. Caliper-check the original when exact length is critical.
• This adapter plugs into Surface Dock Model 1661 only. It does not connect directly to a Surface Pro, Surface Laptop, Surface Book, or Surface Go computer.
• The dock can pass up to 60W to the connected computer; the remaining adapter capacity supports the dock electronics and attached peripherals.