Antminer L3+ Maintenance Guide

Table of Contents

Cryptocurrency mining can be a lucrative business, but it requires continuous maintenance and upkeep to keep your mining equipment running smoothly. When your mining hardware fails, it can result in significant profit losses. That’s why it’s essential to have a maintenance guide for your mining equipment. In this blog post, we will introduce you to the maintenance guide for Antminer L3+ provided by D-Central, a leading provider of cryptocurrency mining equipment and services. This guide covers the tools and spare parts you need to repair your Antminer L3+ and the maintenance requirements to ensure optimal performance. Keep reading to learn more about this essential maintenance guide for your mining equipment.

Preparation and Maintenance Guidelines

It’s essential to take the time to properly prepare and maintain components before, during, and after installation. This includes applying thermal gel for better heat transfer, forming air ducts for better airflow, connecting power supplies in the correct sequence, fixing chips to prevent overheating, and ensuring test fixtures meet production requirements. Additionally, these guidelines should also include instructions on cleaning components with approved solvents such as isopropyl alcohol or distilled water, as well as how to store components away from extreme temperatures and humidity levels safely. Finally, regularly scheduled maintenance checks should be carried out every few months or at least annually to guarantee the proper functioning of all parts within the system.

Preparation Requirements for Repair Platform, Tools, and Equipment

I. Platform Requirements

  • The necessary requirements for the platform include a workbench for repairing Antminer L3+ hash boards that must be properly grounded. In addition, an anti-static wrist strap and grounding are also required to prevent static electricity from damaging the materials being worked on.

II. Equipment Requirements

  • Thermostat soldering iron at 350-450 degrees Celsius, pointed solder tip for small patches like r-c.
  • Heat gun for chip disassembly and soldering, no long time heating in case of PCB blistering.
  • APW3 power source with 12V and 133A Max output to test the hash board.
  • Multimeter, tweezer, L3+ hash board tester (oscilloscope preferred).
  • Scaling powder, cleaning water and anhydrous alcohol; cleaning water is used to clean the residue and appearance after maintenance.
  • Tin grinder, tin stencils, and tin cream; implant tin for chips upon renewals.
  • Heat-Conducting Glue, black (3461), to glue cooling fin after maintenance.

III. Test Tool Requirements


  • ARC Antminer Hashboard Tester
  • Lab PSU 10-30V / 1-15A

Bitmain Kit

  • APW9+ power supply and power patch cord for hash board power supply
  • Use the test fixture of the V2.3 control board (test fixture material number ZJ0001000001).

IV. Maintenance Auxiliary Materials/Tools Requirements

  • Solder Paste 138°C, flux, Mechanic lead-free circuit board cleaner, and anhydrous alcohol.
  • Mechanic lead-free circuit board cleaner cleans up the flux residue after maintenance.
  • Thermally conductive gel is used to apply to the chip surface after repair.
  • Ball-planting steel mesh, desoldering wick, and solder balls (the recommended ball diameter is 0.4mm).
  • When replacing a new chip, it is necessary to tin the chip pins and then solder them to the hash board. Apply thermally conductive gel evenly on the chip’s surface, then lock the heatsink.
  • Serial port code scanner.
  • Serial port adapter board RS232 to TTL adapter board 3.3V.
  • Self-made short-circuit probe (use the pins for wiring and welding and heat the shrinkable sleeve to prevent short-circuit between the probe and the small heatsink).

V. Common Maintenance Spare Material Requirements

  • 0402 resistor (0R, 10K, 4.7K,)
  • 0402 capacitor (0.1uF, 1uF)

Maintenance Requirements

  • Maintenance personnel should have good knowledge of electronics, at least one year of experience, and a strong mastery of QFN encapsulation and soldering techniques.
  • Check the maintenance work at least twice, and ensure that the result is satisfactory each time.
  • Pay close attention to the techniques used during maintenance, ensure that there is no obvious PCB deformation after changing any fittings, and check for missing/open circuits and short circuits on parts.
  • Check the maintenance target, corresponding test software parameters, and the hash board tester.
  • Check the tools and testers.

Overview of Antminer L3+ Components

L3+ Hashboard Structure

  • The L3+ has 12 voltage domains connected in series, each domain has 6 BM1485 chips, and the entire board has 72 BM1485 chips.
  • The BM1485 chip has built-in voltage-reduction diodes, determined by the designated pin of the chip.
  • The L3+ has a 25M monocrystal oscillator on the clock, connecting in series from the 1st chip to the last chip.
  • The L3+ has independent cooling fins on the back of each chip. SMT paster on the front and the one on the back are fixed on the back of the IC by heat conducting glue after initial testing. After every maintenance, they should be fixed by black heat conducting glue (evenly distributed) on the back of the IC.

Signal Direction of L3+ Chip

The CLK signal flow is produced by a Y1 25M crystal oscillator and transmits from the No. 1 chip to the No. 72 chip. In standby and computing modes, both voltages are 0.9V. The TX (CI, CO) signal flow passes through IO mouth pin 11 and transmits from the No. 1 to the No. 72 chip. The voltage is 0V when the IO wire is not plugged, and it is 1.8V during computing. The RX (RI, RO) signal flow returns from the No. 72 to the No. 1 chip and then returns to the control panel from IO mouth pin 12. The voltage is 1.8V when the IO signal is not plugged, and it is also 1.8V during computing. The B (BI, BO) signal flow lowers the electrical level from the No. 1 to the No. 72 chip. The voltage is 0V when the IO wire is not plugged or during standby, and the signal impulse is about 0.3 during computing. The RST signal flow passes through IO mouth pin 15 and transmits from the No. 1 to the No. 72 chip. The voltage is 0V when the IO signal is not plugged or during standby, and it is 1.8V during computing.

The hash board contains several critical circuits on its front, including RST, BO, RI (RX), CO (TX), and CLK signal testing points among chips. These testing points help in fault-locating during maintenance. The entire board has 12 voltage domains, and each domain has 6 chips. The six chips in the same voltage domain are in parallel power supply and then connect to other voltage domains in series. The voltage domains have several testing points, including CORE voltage, LDO-1.8V, PLL-0.9V, DC-DC output, and booster voltage 14V. During maintenance, these testing points must be tested, and the fault points can be inferred based on the circuits before and after the testing point.

Testing Points among Chips

During maintenance, testing the testing points among chips is the most direct method of locating faults. The L3+ hash board is arranged with RST, BO, RI (RX), CO (TX), and CLK signal critical circuits on its front, as shown in Fig 3.

The entire board has 12 voltage domains, with each domain having 6 chips that are in parallel power supply and then connect other voltage domains in series, as depicted in Fig 4. The voltage domain single chip principle analysis, shown in Fig 5 and Fig 6, includes the pin functions of the BM1485 chip.

During maintenance, ten testing points on the front and back of the chip are mainly tested, with five on each side for CLK, CO, RI, BO, and RST. Other testing points include CORE voltage, LDO-1.8V, PLL-0.9V, DC-DC output, and booster voltage 14V.