Introduction to Antminer S21 Hash Board Repair

This comprehensive guide is designed to provide detailed instructions on how to properly repair and maintain the Antminer S21 hash board, ensuring optimal performance and longevity of your mining equipment.

I. Preparation of Maintenance Platform, Tools, and Equipment


1. Platform Requirements

  • Anti-static repair workbench that must be grounded.
  • Anti-static wrist strap and grounding to prevent static damage.



2. Equipment Requirements

  • Thermostatic soldering iron set to 350-380 degrees Celsius with a fine-tip suitable for soldering small SMD resistors and capacitors.
  • Hot air gun and BGA rework station for chip/BGA removal and soldering.
  • Multimeter (Fluke recommended) with soldering steel needles covered in heat-shrink tubing for precise measurement.
  • Oscilloscope for signal analysis.
  • Ethernet cable for a stable Internet connection during repair diagnostics.



3. Repair Test Tools Requirements

  • Use a power supply like the APW171215a, 12V-15V, V1.3, calibrated to safety regulations. Alternatively, use other specified power supplies from the BOM with power adapter cables.
  • Test fixture V2.1 or V2.3 control board (material number ZJ0001000004) with discharge resistors (20 ohms, above 100W, cement resistors).



4. Repair Auxiliary Materials/Tools Requirements

  • Solder paste M705, flux, and cleaning solution with anhydrous alcohol for post-repair cleaning.
  • Thermal gel (specification: Fujipoly SPG-30B) to apply on the chip surface after repair.
  • Tin tool stencil for BM1368 LGA (6mm * 8mm chip size), desoldering wire, and solder balls (recommended diameter 0.4mm).



5. Common Spare Parts for Repair

  • SMD resistor 33 ohms, ±1%, 1/20W, 0402
  • SMD resistor 10K, ±1%, 1/16W, 0402
  • SMD resistor 0 ohms, ±5%, 1/16W, 0402
  • SMD ceramic capacitor 1uF, +/-10%, 16V, X5R, 0402
  • SMD ceramic capacitor 1uF, 6.3V, 20%, X5R, C0201
  • SMD ceramic capacitor 22uF, +/-20%, 6.3V, X5R, 0603


II. Repair Requirements and Procedure


1. Chip Replacement and Soldering

  • Pay careful attention to operation techniques when replacing chips. Check for any visible deformation of the PCB after replacing any components. Ensure there are no missing parts, open circuits, or short circuits around the replaced components.



2. Qualifications and Skills of Repair Personnel

  • Repair personnel must have significant electronics knowledge, at least one year of repair experience, and be proficient in BGA/QFN/LGA soldering techniques.



3. Testing Post-Repair

  • The hash board must be tested at least twice with both results confirming functionality to be considered OK. Each work order should have a corresponding number of hash board serial numbers, and each board must be unique.



4. Detailed Testing Instructions

  • Ensure the test software parameters and the version of the test fixture are correct. First, perform a chip detection test. If it passes, proceed with the PT3 sweep function test. Ensure the heatsink assembly is properly installed for functional testing. Apply thermal gel evenly on the chip surface when installing the heatsink. Connect the fan to the test fixture for controlled testing.



5. Cooling and Measurements During Repairs

  • Without adequate fan cooling or during continuous PT1 testing, the chip may overheat, risking damage to the board. Always use a fan to blow air on the TOP side during measurement.



6. Final Precautions Before Reassembly

  • After the PCBA with the removed heatsink is repaired and confirmed OK, be sure to reapply thermal paste to the heatsink before reinstallation and subsequent testing to ensure proper operation of the entire machine.



This detailed repair manual for the Antminer S21 hash board covers all necessary steps and precautions to ensure effective and safe repairs, maintaining the hash board in optimal working condition.