Antminer S19+ Maintenance & Repair Guide

Maintaining an Antminer S19+ mining rig can be a daunting task. Following the proper maintenance guide is essential to ensure that your mining rig runs efficiently and without interruption. This maintenance guide will provide step-by-step instructions for inspecting and repairing your Antminer S19+ and tips for troubleshooting any issues that may arise. It will also cover recommended practices for routine inspection, testing of hash boards, locating faulty chips, resoldering chips, and more. By following this guide closely, you can maximize the performance of your Antminer S19+ and keep it running smoothly.

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

• 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 soldering iron (350°C-380°C) with a pointed tip for soldering small patches such as chip resistors and capacitors.
• Hot air guns and BGA rework stations are used for chip / BGA disassembly and welding.
• Multimeter with welded steel pins and heat-shrinkable sleeves for easy measurement. The recommended model is the Fluke 15b+ multimeter.
• Oscilloscope. The recommended model is UTD2102CEX+. A network cable is required for an internet connection and a stable network.

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

• 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

1. 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, open, and short circuits.
2. Maintenance personnel must have electronic knowledge, at least one year of maintenance experience, and proficiency in BGA/QFN/LGA packaging and welding technology.
3. After repair, the hashboard must be tested more than twice, and all tests must pass.
4. 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.
5. 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. Two hash boards should be placed simultaneously to form an air duct when using the chassis to dissipate heat. For single-sided testing in production, the air duct must also be formed.
6. When measuring the signal, use fans to dissipate heat and ensure the fans are at full speed.
7. 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.
8. 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. If you do not follow this order, it may cause damage to U1 and U2.
9. Before testing the pattern, the repaired hashboard must cool down before testing; otherwise, it will lead to testing NG.
10. 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 S19+ Components

S19+ Hashboard Structure

The S19+ hash board has 80 BM1398AC chips that are divided into ten domains, with each domain consisting of 8 ICs. The BM1398AC chip operates on a voltage range of 1.34V-1.4V. For the tenth domain, there are two groups of LDO for each 1.8V and 0.8V. The 14V output from the VDD_14V powers the 1.8V LDO and outputs 1.8V. The 1.8V output of this domain provides 0.8V via LDO. The ninth domain is powered by the VDD of the following domain and outputs 1.8V. There are three groups of 0.8V LDO for domains 1-9. The VDD of the following domain provides 0.8V via LDO. The voltage of each domain retreated is reduced by 1.38V.

 

Signal Direction of L7 Chip

The S19+ chip has four types of signals – CLK, TX, RX, BO, and RST – that flow in different directions between chips 01 and 80. Here’s a breakdown of the details for each signal:

1. CLK: The CLK signal is generated by a 25M oscillator (Y1) and flows from chip 01 to chip 80. The voltage range is between 0.7V and 1.3V.
2. TX: The TX signal flows from the IO port’s seven pins (3.3V) into IC U4 through level conversion, and then it’s transmitted from chip 01 to chip 80. The voltage is 0V when the IO signal is not inserted, and 1.8V during operation.
3. RX: The RX signal flows from chip 80 to chip 01, returns to the signal cable terminal pin 8 through U2, and then back to the control board. The voltage is 0.3V when the IO signal is not inserted, and 1.8V during computing.
4. BO: The BO signal flows from chip 01 to chip 80, and its voltage measures 0V with a Fluke 15B+ multimeter.
5. RST: The RST signal flows from pin 3 of the IO port, and then it’s transmitted from chip 01 to chip 80. The voltage is 0V when no IO signal is inserted and the equipment is on standby, and 1.8V during computing.

In summary, the S19+ chip has five different signals that transmit in different directions and have varying voltage levels depending on whether or not the equipment is on standby or in operation.

Antminer L7 Structure

The entire miner consists of three hash boards, one control board, an APW12 power supply, and four cooling fans.

Identifying Common Issues with Hashboards and Troubleshooting Procedures

Phenomenon 1: The detection chip on a single hash board test shows 0

Check the voltage output of VDD_14V and the voltage domain. The voltage of each voltage domain should be around 1.34V-1.4V.

• If there is a 14V power supply, there should be a domain voltage.
• If there is no VDD_14V, check the output of PSU.
• If the output is normal, then check the PIC circuit (follow the below steps to check the PIC circuit).
• If 14V has a power supply but no domain voltage, continue to check.

To check the PIC circuit

• Measure whether there is an output on the eleventh pin of U4 and the voltage is around 3.3V.
• If there is, continue troubleshooting the problem.
• If there is no 3.3V, check the connection status of the hash board tester cable and whether the hash board is okay.
• Reprogram the PIC if needed.
• Refer to Figures 5-2, 5-3, 5-4, and 5-6.

Check the boost circuit output

• Measure the 14V voltage on D1.

Check the output of each group of LDO 1.8V or PLL 0.8V

• Check the output of each group of LDO 1.8V or PLL 0.8V

Check the chip signal output (CLK/CI/RI/BO/RST)

• Refer to the voltage value range described by the signal trend.
• If the measurement encounters a significant deviation of the voltage value, it can be compared with the measured value of the adjacent group to determine.
• PS: If the hash board is not powered or powered off according to the test sequence, causing R89, R90, U2, and U4 to burn out, the chip will report 0.
• When the EEPROM NG is displayed on the LCD screen of the hash board tester, check whether the welding of U10 is normal.
• If the PIC sensor NG is displayed on the LCD screen of the hash board tester, and the test read temperature is abnormal, follow the below steps to troubleshoot.
• Check whether the four resistors of R71~R77 are welded abnormally, and check whether the welding of PIN2, 3 of U4 is standard.
• Check whether the four temperature sensors U7, R78, R80, R81; U8, R83, R84, R88; U9, R92, R94, R95; U11, R96~R98, and the matching resistance welding are abnormal.
• The temperature sensor is located on the back of the PCB, while the resistance is on the front and back.
• Check the welding quality of the heat-sensitive chip and the small heat sink.
• The deformation of the large heat sink material will cause poor heat dissipation of the chip and affect the temperature difference.

 

Phenomenon 2: Single hashboard detection chip is not complete

LCD display ASICNG:

• If ASICNG displays (0), check the total voltage of the measuring domain and the boost circuit 14V, and short-circuit the RO test point and 1V8 test point between the first and second chip to find the problematic chip.
• If a chip is not found, there may be a problem with the 1.8V or 0.8V LDO circuit, the ASIC chips not being soldered well, the circuits of U2 and U4, or R89 or R90.
• If one chip is found, check subsequent chips by short-circuiting the 1V8 and RO test points, and continue to investigate with dichotomy until the problematic chip is found.

LCD display ASIC75:

• If ASIC75 reports (75), it means only 75 chips are found at 12M baud rate out of 76 chips detectable at 115200 baud rate. Short-circuit the 1V8 test point and the RO test point between the 38th and 39th chips using the dichotomy method to locate the problematic chip.
• If short-circuiting 47 chips, but the log reports 46, it indicates that the 47th chip cannot be detected, and it should be replaced.

LCD display ASICNG:

• If ASICNG displays (X) and the test time is almost the same as the good board, focus on the 6 resistors of the Xth chip that may have abnormal resistance welding.
• If the test time is almost twice as long as the good board, the chip may not be soldered well, and it is recommended to directly measure the domain voltage to locate the problem. The 1V8 and RO short-circuit methods used in section 1) can also locate the abnormal position.

Phenomenon 3: Single hashboard Pattern NG, indicating that the nonce response data is incomplete (PT2 station)

• Significant differences between the characteristics of the chip and other chips cause this issue.
• The chip die is found to be damaged and needs to be replaced.
• Replacement rules based on log information are as follows: If the appearance of the chip is not damaged, replace it with the lowest response rate in each domain.
• Example: in a test log, chips asic[36], asic[37], asic[43], and asic[75] have low response rates.
• If chips asic[36] and asic[37] are in the same domain, replace the one with the lower nonce in asic[36] and asic[37].
• At the same time, replace chips asic[43] and asic[75].
• Special attention should be paid to the domain numbers, and asic starts from 0.

Phenomenon 4: PT1 chip test is OK, PT2 function test always reports a certain chip NG;

The first step is to check the appearance of the chip to determine if there are any visible signs of damage. If the chip appears to be in good condition, the next step is to measure the capacitor or resistance in front of the chip. This can help identify the root cause of the issue, which is typically due to poor soldering of the chip, a damaged chip capacitor or resistor, or abnormal resistance. By identifying and addressing the underlying cause of the issue, the chip can be repaired and returned to proper functioning.

Troubleshooting Common Miner Failures

A preliminary test of the whole machine

Referring to the test process document, the general problems are assembly and control board process problems. Common problems include the inability to detect the IP, an abnormal number of detected fans, and abnormal detected chain. Any issues arising during the test should be repaired according to the monitoring interface, and the test LOG prompts. The maintenance methods for the initial and aging tests of the whole machine are the same.

Aging Testing of the Miner

The aging test should be repaired according to the monitored interface test. For instance:

• Abnormal fan display: In such cases, we need to check whether the fan works normally, whether the connection with the control board is normal, and whether the control board is abnormal.
• Less chain: This means that three boards are missing one board. In most cases, there is a problem with the connection between the hash and control boards. Check the cable to see if there is an open circuit. If the connection is OK, you can test the board to PT2 to see if it can be tested. If it can be tested, it can be determined that it is the control board. If the test fails, use the repair method of PT2 maintenance.
• Abnormal temperature: Generally, the temperature is high. The maximum PCB temperature set by our monitoring system cannot exceed 90℃. The fan will alarm, and it will not work normally. Generally, the ambient temperature is too high, and the abnormal operation of the fan will also cause abnormal temperature.
• An insufficient number of chips: If the number of chips is insufficient, you can refer to PT2 for testing and repair.
• After running for some time, there is no hashrate, and the connection of the mining pool is interrupted; check the network.

If the miner still loses hashrate, reduce the frequency, and other conditions remain unchanged. Let the miner mine to see if it will lose hashrate and whether the hash board will hit X. If it still hits X in losing hashrate, then remove the heat sink of the hashboard for mining and wait for the hashrate to drop. Measure whether the domain voltage is normal. Generally, the domain voltage will be abnormal in the problematic domain. Then measure the RI signal to see if the RI signal is broken. If the RI signal is missing the chip is short-circuited or damaged after being tinned.

Other Considerations and Maintenance Flow Chart

 

• To conduct a routine inspection on a hash board that needs repair, examine it visually for signs of deformation or scorching on the PCB. If these issues are present, they must be addressed first. Next, look for burnt marks, offset parts, or missing components.
• Once the visual inspection is completed, test the impedance of each voltage domain to detect any short circuits or open circuits. If any are found, they must be addressed first. Additionally, check if the voltage of each domain is about 0.36V.
• After passing the routine test, conduct a chip test using a hash board tester. Use the test result to locate the faulty chip. From the near faulty chip, check the chip test points and voltages such as VDD0V8 and VDD1V8.
• To find the fault point, follow the signal flow, except for the RX signal, which reverses the signal. Several signals are forward transmissions, including CLK, CO, BO, and RST. Identify the abnormal fault point through the power supply sequence.
• When locating the faulty chip, re-solder it by adding flux around the chip and heating the solder joints of the chip pins until they are dissolved. This will prompt the chip pins and pads to re-run and collect the tin to achieve the effect of tinning again. If the fault remains the same after re-soldering, replace the chip directly.
• To confirm that the repaired hashboard is a good product, use the hash board tester to test it twice with more than two passes each time. After replacing the parts, please wait for the computing board to cool down before testing it for the first time. After the first test is passed, set it aside and let it cool down before testing it again for the second time after a few minutes.