Maintaining your Antminer Z15 can help you maximize its performance and keep it running smoothly. This guide provides step-by-step instructions to help you troubleshoot any issues that may arise with your miner and tips for performing routine maintenance. We’ll cover everything from detecting short circuits and voltage problems to locating faulty chips and resoldering them. With this guide, you’ll be able to handle all of your Antminer Z15‘s maintenance needs quickly and efficiently.
Preparation and Maintenance Guidelines
Preparation Requirements for Repair Platform, Tools, and Equipment
I. Platform Requirements:
To perform maintenance work, an anti-static maintenance workbench is required. It should be grounded, and an anti-static wristband and grounding are necessary.
II. Equipment Requirements:
Constant temperature electric soldering iron (370℃-400℃) and pointed soldering iron tip are used for soldering small patches such as chip resistors and capacitors.
Portable desoldering gun and BGA repair station are used for chip disassembly and welding. Be careful not to heat for a long time to avoid PCB foaming.
APW3/APW3+/APW5 power supply (output 12V, 140A Max) and power adapter cable (made by yourself) are used for the test and measurement of the hash board.
Fluke multimeter, tweezers, V9 test fixture tool (conditional configurable oscilloscope).
Add anhydrous alcohol to flux and board washing water; board washing water is used to clean the flux residue and appearance after maintenance.
Tin tool, Tin tool steel sheet, solder paste; When replacing a new chip, the surface pads of the PIN pins of the chip need to be washed flat, and the chip should be soldered with a BGA repair station after tinning.
Antminer thermosetting adhesive applied to the chip/heat sink after repair.
III. Test Tool Requirements:
ARC Kit
ARC Antminer Hashboard Tester
Lab PSU 10-30V / 1-15A
Bitmain Kit
APW12 power supply: AP12_12V-15V_V1.2 and power adapter cable. It is recommended to use thick copper wire for the positive and negative poles of the power supply to connect the power supply and the power board and only limited to PT1 and maintenance test use.
Use the test fixture of the V2.3 control board (test fixture material number ZJ0001000001). The positive and negative poles of the test jig need to be installed with discharge resistors. Using a cement resistance of 20 ohms and 100W or more is recommended.
IV. Maintenance Auxiliary Materials/Tools Requirements:
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
When replacing a chip, pay attention to the operation method. After replacing any component, check that the PCB board has no obvious deformation. Check the replacement and surrounding parts for missing parts, open circuits, and short circuits.
Maintenance personnel must have electronic knowledge, at least one year of maintenance experience, and proficiency in BGA/QFN/LGA packaging and welding technology.
After repair, the hashboard must be tested more than twice, and all tests must pass.
Check the tools to ensure that the test fixture can work typically. Determine the parameters of the maintenance station test software, the version of the test jig, and other related parameters.
To test repairing and replacing the chip, test the chip first and then do the functional test after it passes. The functional test must ensure that the small heatsink is welded correctly, the large heat sink is installed, and the thermal adhesive gel is applied evenly. When using the chassis to dissipate heat, two hash boards should be placed simultaneously to form an air duct. For single-sided testing in production, the air duct must also be formed.
When measuring the signal, use fans to dissipate heat and ensure the fans are at full speed.
When powering on the hashboard, connect the negative copper cord of the power supply first, then the positive copper cord of the power supply, and finally, insert the signal cable.
When disassembling, reverse the order of installation. First, remove the signal cable, then pull the positive copper cord of the power supply, and finally, remove the negative copper cord of the power supply. If you do not follow this order, it may cause damage to U1 and U2.
Before testing the pattern, the repaired hashboard must cool down before testing; otherwise, it will lead to testing NG.
Pre-tin the chip pins with solder paste to replace a new chip and then solder them to the PCB for repair.
Overview of Antminer Z15 Components
Z15 Hashboard Structure:
The Z15 hash board structure consists of three BM1746 chips, with each chip controlled by a separate power management IC. The working voltage of the BM1746 chip used by Z15 is 0.78V, with an LDO to provide VDDIO 1.8V and VDDPLL 0.7V power supply. The Z15 clock is a 25M crystal oscillator transmitted from the first chip to the third chip in series. During maintenance, it is necessary to test ten signal voltages before and after the chip, including the CORE voltage, LD0-1.8V, PLL-0.7V, and 12V to 5V voltage. The signal directions of Z15 hash board include CLK, TX (CI, CO), RX (RI, RO), BO (BI, BO), and RST. By testing the voltage of each test point on the chip surface of the PCB board, maintenance personnel can determine the fault point and troubleshoot the hash board accordingly.
Signal direction of Z15 hash board:
CLK (XIN) signal flows from chip 01 to chip 03, generated by Y1 25M crystal oscillator. During operation, the voltage is 0.85V.
TX (CI, CO) signal flows from the IO port 7 pin (3.3V) into the level conversion IC U2, and then from the 01 chip to the 03 chip transmission. When the IO line is not inserted, the voltage is 0V, and the power supply voltage during operation is 1.8V.
RX (RI, RO) signal flow direction is from chip No. 03 to chip No. 01, through U1 to the signal cable terminal, pin 3 and back to the control board. The voltage is 0.3V when the IO signal is not inserted, and the voltage during operation is 1.8V.
BO (BI, BO) signal flow is from chip No. 01 to No. 03, and the multimeter measures 0V.
The RST signal flows in from IO port 3 and then is transmitted from chip 01 to chip 03. No IO signal is inserted, and it is 0V in standby and 1.8V in operation.
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The critical circuit of the Z15 hash board:
During maintenance, ten signal voltages are mainly tested before and after the chip, which includes five signals before and after the chip, namely CLK, CO, RI, BO, and RST. Other tests include CORE voltage, LD0-1.8V, PLL-0.7V, and 12V to 5V.
To detect any issues, each chip has a lead-out test point, the I0 line should be plugged in, and the test fixture test button should be pressed to activate the PIC. The expected normal voltage of each test point during this test should be as follows:
CLK: 0.85V
CO: 1.6-1.8V
RI: 1.6-1.8V. If the voltage is abnormal or too low, it may cause abnormalities in the hash board or a hash rate of 0.
BO: 0V when no hash operation is performed, and 0V when hash operation is performed.
RST: 1.8V. The reset signal will be output again every time the test fixture’s test key is pressed.
If any of the above test point status and voltage are abnormal, the fault point should be inferred based on the circuit before and after the test point.
The failure and performance issues
Firstly, the abnormal LDO 1.8V or PLL 0.7V can cause data to be crossed and prevent the chip from being fully read, which can lead to missing chips or dropped boards in the entire miner.
 
 
