Antminer D7 Maintenance Guide

Welcome to this maintenance guide, crafted with care by D-Central, your go-to source for critical ASIC repair resources. We have put in much effort to create this guide, and we would love your support. If you find this guide helpful, please consider giving us a shoutout, a review, a share, a subscription, or a tip. Bitcoin mining is our passion, and we are happy to share our knowledge with the world. In this guide, you will find step-by-step instructions for properly installing, testing, and troubleshooting various components to ensure optimal performance. Our guide covers important topics such as thermal adhesive gel application, air duct formation, power supply connection sequence, and chip repair. We also provide production requirements for test fixtures that must be met to guarantee accurate results. With the help of our guide, you will have all the information you need to maintain your Antminer D7 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. It is recommended to use a cement resistance of 20 ohms and 100W or more.

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 surface of the chip, and 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, 51R, 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 parts, open circuits, 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. 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.
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 of the power supply. 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.

Principle Overview

1. Working Structure of D7 Hashboard:

The D7 hashboard has 70 Antminer BM1764 chips divided into 35 domains, each consisting of 2 ASIC chips. The BM1764 chips operate at a voltage of 0.3V. The boost circuit U238 outputs 20V voltage, which is then output by the linear regulator (U295 U16 U14 U307 U310 U313) to provide 1.8V to the 29th-34th groups (6 groups in total) to supply LDO 1.8V power. The LDO (U294 U15 U13 U306 U309 U312 U187 U188 U190 U191 U193 U194) outputs 0.8V. The 28th group-1st group and 35th groups are provided by VDD 13V through LDO to supply 1.8V and 1.8V again through the linear regulator to provide 0.8V. The domain voltage is about 0.3V.

Please refer to the figures for details.

 

 

 

2. BXD34601 Hash Board Boost Circuit:

The boost is powered by 13V from the power supply and turned to 20V.

Please refer to the figures for details.

3. D7 Chip Signal Direction:

1. The CLK (XIN) signal flow is generated by a Y2 25MHZ crystal oscillator and transmitted from chip No. 01 to chip No. 70. The voltage is about 0.9V.
2. The RST and CI signals flow from the 3rd pin (3.3V) of J3, are converted by the level conversion IC U1-U3-U4, and then transmitted from chip No. 01 to chip No. 70.
3. The RX (RI, RO) signal flow direction is from chip No. 70 to chip No. 01 and then returns to pin 8 of the signal cable terminal through U2 and finally back to the control board.
4. The BO (BI, BO) signal flow is from chip No. 01 to chip No. 70.

4. The Whole Miner’s Structure:

The miner consists of 3 hash boards, 1 Antminer D7 control board, an APW12 power supply, and four cooling fans.

Common Problems and Troubleshooting Steps of Hashboard

Phenomenon 1: The single-board test detects that the chip is 0 (PT1/PT2 station)

• Check the power output. Please check the voltage of the circled part in the figure provided.

 

 

• Check the voltage output of the voltage domain. The voltage of each voltage domain is about 0.3V, and the 13V power supply generally has the domain voltage. Priority should be given to measuring the output of the power supply terminal of the hash board and whether the MOS is short-circuited (measure the resistor value between pins 1, 4, and 8). If 13V is powered, but there is no domain voltage, continue to check.

 

• Check the PIC circuit. Measure whether pin 11 of U6 has an output (3.3V). If yes, please continue to troubleshoot the problem. If not, please check that the connection between the test fixture cable and the hash board is OK, and reprogram the PIC.

 

 

• Check the output of the booster circuit, and test C69. The voltage can be measured to 20V.

 

• Check each group of LDO 1.8V or PLL 0.8V output. Please refer to the figures for details.

 

 

• Check the chip signal output (CLK/CI/RO/BI/RST). The voltage value range described by the reference signal direction. If the measurement encounters a large deviation of the voltage value, it can be compared with the measurement value of the adjacent group.

 

Additional troubleshooting steps:

• When EEPROM NG is displayed on the LCD screen of the test fixture, check whether U10 is soldered normally.

 

• When the PIC sensor NG is displayed on the LCD screen of the test fixture, the test reading temperature is abnormal. Follow the steps provided to troubleshoot.
• Check whether the four resistors R214, R215, R1071, R1076 are abnormally welded.
• Check whether the welding of U5, U7, U8, U9 temperature sensor chips is normal, the temperature sensor position is as shown in the figure, and also need to check whether the 3.3V power supply of the temperature sensor chip is normal.
• Check the welding quality of the chip connected to the temperature sensor and the small heatsink. The deformation of the large heatsink material will cause poor heat dissipation of the chip and affect the temperature difference.

 

Phenomenon 2: Lack of single-board detection chips

The Antminer Hashboard Tester you are using is indicating a lack of chips, the following steps can be taken to identify the problem:

• Measure the total voltage of the measurement domain and the boost circuit.
• If 20V is normal, short-circuit the RX test point and the 1V8 test point between the 1st and 2nd, and run the program to look at the serial port log. (If working jump to 2nd section)
• If 0 chips are still not detected, there are several possible causes. First, use a multimeter to check whether the voltages of the 1V8 and 0V8 test points are 1.8V and 0.8V. If not, the 1.8V and 0.8V LDO circuits in this domain may be abnormal, or the two ASIC chips in this domain may not be soldered properly.
• Short circuits in the 0.8V and 1.8V SMD filter capacitors may also be the cause. Check whether the circuits of U1, U2, and U5 are abnormal, such as poor soldering.
• Additionally, check whether the first chip has pins that are not soldered well.

• If one chip is found short-circuiting chips 1 and 2, it indicates that the first chip and the previous circuit are functioning properly.
• Short-circuit the 1V8 and RX test points between the 38th and 39th chips.
• Check the log to see if all 38 chips can be detected.
• If all 38 chips are detected, the first 38 chips are functioning correctly.
• If no chips are detected, check whether the 1V8 is normal.
• If the 1V8 is normal, then there is an issue with the chips after 38.
• Repeat the process by short-circuiting between different chips until the problematic chip is located.

Phenomenon 3: Incomplete reply nonce data (PT2 station)

When operating the Bitmain Testjig PT2 stations, it’s crucial to take note of the ASIC numbering, which starts from 000 and goes up to 069. In the event of incomplete reply nonce data, it could imply that there is an issue with the ASIC. To troubleshoot this, replace the missing ASIC or ASICs that are lacking the most nonces, and then attempt the test again. Continue the process until you achieve at least 95% of the board’s anticipated hashrate.

Phenomenon 4: PLUG OFF BEFORE TEST OVER Error Message

While testing a chip, if the PT2 function displays “PLUG OFF BEFORE TEST OVER” this may be because the tester unplugged the cable before the voltage dropped to 0. To resolve this issue, the fixture will need to be restarted.

PT2 Test Environment Requirements

The test environment’s temperature should be maintained between 20°C and 30°C. If the ambient temperature exceeds 35°C, the software will stop the test.

PT2 Test Power Supply Requirements

When the PT2 test fixture’s power supply is under a load of 1500 watts (for example, when testing a board), the actual output voltage must not be lower than the voltage set in the configuration file. For instance, if the configuration file specifies a trial production of 15V, the output voltage of the power supply must not be lower than 14.97V when loaded with 1500 watts.

Troubleshooting Common Miner Failures

Initial Testing of the Miner

Refer to the test process file for common problems during the assembly and control board process. Common issues include IP detection failure, abnormal fan speed, and abnormal chain detection. If any issues are detected during testing, follow the repair methods suggested in the monitoring interface and test log prompts. The repair methods for initial and aging tests of the miner are the same.

Aging Testing of the Miner

During the aging test, perform maintenance according to the monitored interface test, such as:

• Abnormal Fan Display: Check if the fan is working properly, if the connection with the control board is normal, and if the control board is malfunctioning.
• Missing Hash Board: This means that 3 boards are missing 1 board. In most cases, there is a problem with the connection between the hash board and the control board. Check for any open circuits in the cable. If the connection is okay, test the board for 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.
• Abnormal Temperature: Generally, the temperature is high. The maximum PCB temperature set by our monitoring system cannot exceed 90°C. If it exceeds 90°C, the miner will alarm and cannot work properly. Generally, high ambient temperature and abnormal fan operation can cause abnormal temperature.
• Insufficient Hashrate: If the number of chips is insufficient, refer to PT2 for testing and repair.
• No Hashrate After Running for a Period of Time: Check the network connection and mining pool.
• Normal Aging Test State: A miner is in good condition if it passes the aging test.
• Low Hashrate on One Board: If the first board has no hash rate after running for about 3 minutes, test the board PT2 to check if it is okay. If the test chips are not all checked, repair the board. If the normal gear is okay after the test, take out the board separately and use the test fixture to fix it. The tool is transported into a Debug master chip program for mining, and the fan speed is debugged to 100%. The voltage and frequency are adjusted to the working voltage and frequency of the whole miner. Let the miner mine and see if the miner loses hash rate.

If the miner still loses hashrate, reduce the frequency to 400M 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, basically, the chip is short-circuited or damaged after being tinned.

Other Considerations and Maintenance Flow Chart

 

• Routine Inspection: Start with a visual inspection of the hash board to be repaired for PCB deformation, scorching, and any burn marks or missing parts. Then, test the resistor value of each voltage domain to detect short circuits or open circuits. Check if the voltage of each domain is about 0.32V.
• Chip Inspection: After the routine inspection is OK, perform chip inspection with a test fixture and determine the positioning according to the test results.
• Check Chip Test Points: Based on the test fixture display results, check the chip test points (CO/NRST/RX/XIN/BI) and voltages such as VDD0V8 and VDD1V8.
• Follow Signal Flow Direction: Transmit the RX signal in the reverse direction (chips 70 to 1), and several signals CLK CO BO RST are transmitted in the forward direction (1-70). Find the abnormal fault point through the power supply sequence.
• Locate Faulty Chip: Re-solder the chip by adding flux around the chip and heating the solder joints of the chip pins to a dissolved state. Promote the chip pins and pads to re-run in and close the tin. If the fault remains the same, replace the chip directly.
• Test Hash Board: After repairing the hash board, test it with the test fixture at least twice before it is judged as a good product.
• Record Maintenance: Make relevant maintenance/analysis records, including date, SN, PCB version, tag number, cause of failure, and attribution of responsibility for failure. Prepare for feedback to production, after-sales, and research and development.
• Install Hash Board: After recording, install the hash board into a complete miner for regular aging.
• Streamline Good Products: Good products repaired at the production end should be streamlined from the first station of production, including appearance inspection and the PT1/PT2 test station.

Remove Heat Sink: Remove the large heat sink of the repaired hash board and brush the thermal conductive gel again before it can be streamlined.