Bitmain Antminer D7 Hash Board Repair Guide

To get your Bitmain Antminer D7 hash board fixed and ready to start mining DASH, follow the instructions in the guide below.

In this blog, we will focus on 4 common problems and the steps to fix them.

Quick View:

• The single-board test detects that the chip is 0 (PT1/PT2 station)
• The single-board detection lack of chips (PT1/PT2 station)
• Incomplete reply nonce data (PT2 station)
• The PT2 function displays PLUG OFF BEFORE TEST OVER when the test chip test is successful.

We’ll present a comprehensive guide for fixing your Bitmain Antminer D7 hash board. Read on to discover more.

Preparation Requirements for Repair Platform/tools/equipment

1. Platform Requirements:

Grounding, an anti-static wristband, and a maintenance workbench (which must be grounded).

2. Equipment Requirements:

(1) Constant temperature soldering iron (350°C-380°C), pointed soldering iron tip is used to solder small patches such as chip resistors and capacitors;

(2) Hot air gun and BGA rework station are used for chip / BGA disassembly and welding;

(3) Multimeter with welded steel pins and heat-shrinkable sleeves for easy measurement (Fluke 15b+ multimeter is recommended);

(4) Oscilloscope (recommended oscilloscope UTD2102CEX+), network cable (requirements: Internet connection, stable network)

3. Test Tool Requirements:

(1) APW12 power supply: AP12_12V-15V_V1.2 and power adapter cable (made by yourself: use thick copper wire for the positive and negative poles of the power supply to connect the power supply and the power board, it is recommended to use 4AWG copper wire with a length of less than 60cm, only limited to PT1 and maintenance test use), used for hash board power supply;

(2) Utilize the test fixture made from the V2.3 control board (ZJ0001000001). Discharge resistors must be mounted on the test jig’s positive and negative poles. A cement resistance of 20 ohms and a power output of 100W or higher is advised.

4. Maintenance Auxiliary Materials / Tools Requirements:

(1) Solder Paste 138°C, flux, Mechanic lead-free circuit board cleaner and anhydrous alcohol;

(2) Mechanic lead-free circuit board cleaner is used to clean up the flux residue after maintenance;

(3) Thermally conductive gel is used to apply on the chip surface after repair;

(4) Ball-planting steel mesh, desoldering wick, and solder balls (the recommended ball diameter is 0.4mm);

(5) The chip pins must be tinned and soldered to the hash board before a new chip can be installed. After evenly applying thermally conductive gel to the chip’s surface, lock the heat sink.

(6) Code reader for the serial port.

(7) RS232 to TTL converter board with serial port, 3.3V.

(8) Short-circuit probe that was made on one’s own (used pins for welding and wiring; a shrinkable sleeve needed to be heated to prevent a short between the probe and the small heat sink).

5. Common Maintenance Spare Material Requirements:

0402 resistor (0R, 51R, 10K, 4.7K,);

0402 capacitor (0.1uF, 1uF)

Maintenance Requirements

1. When changing the chip, pay close attention to the procedure. There is no obvious deformation of the PCB board after any accessories have been replaced. For missing parts, open circuits, and short circuits, examine the replacement parts and the surrounding components.

2. Maintenance staff members must be knowledgeable in specific electronic concepts, have at least a year of maintenance experience, and be skilled in BGA/QFN/LGA packaging and welding techniques.

3. The hash board must undergo more than two tests following repairs to ensure that everything is in working order.

4. Examine the tools, see if the test fixture operates normally, ascertain the settings for the maintenance station test software, the version of the test jig, etc.

5. It is essential to test the chip before performing the functional test for the test of chip repair and replacement. The large heat sink must be installed in its proper location, each thermal adhesive gel must be applied evenly, the cooling fan must be running at full speed, and the small heat sink must have been successfully welded, according to the functional test. Two hash boards should be placed simultaneously to create an air duct when using the chassis as a heat sink. The single-sided test of the production should also ensure that the air duct is formed (Important)

6. Support four fans that are running at full speed to remove heat when measuring the signal.

7. The signal cable must be inserted after the power supply’s positive and negative copper cords have been connected, and before the hash board can be turned on. Reversing the installation order is necessary for disassembly. Remove the signal cable first, then the power supply’s positive copper cord, and finally the power supply’s the negative copper cord. It is very simple to damage U1 and U2 if you do not follow this order (not all chips can be found). The repaired hash board needs to cool down before being tested for the Pattern; otherwise, testing will result in testing PNG.

8. Ensure that the new chip is pre-tinned and then soldered to the PCBA for repair by brushing the pins and solder paste.

9. On the maintenance side, each test fixture is examined in both the scan code and Test_Mode modes. After the test passes, the production side will be streamlined from the first test station, and the standard installation will be aged (installed to the same level).

Common Problems and Troubleshooting Steps of Hash Board

Phenomenon 1: the Single-board Test Detects That the Chip is 0 (PT1/PT2 Station)

The first step is to check the power output. Please check the voltage of the area in the figure below that is circled.

The second step: check the voltage output of the voltage domain

The 13V power supply typically has the domain voltage, which is approximately 0.3V for each voltage domain. Priority is given to determining whether the MOS is shorted out (measure the value of the resistor between pins 1, 4, and 8), as well as the output of the hash board’s power supply terminal. Check again if 13V is powered but no domain voltage is present.

The third step: check the PIC circuit

Check to see if U6 pin 11 is producing 3.3V. If you answered “yes,” kindly carry on analyzing the issue. If not, make sure the test fixture cable’s connection to the hash board is secure before reprogramming the PIC.

Phenomenon 2: the Single-board Detection Lack of Chips (PT1/PT2 Station)

a) When the ASIC NG: (0) message appears on the test fixture’s LCD screen, measure the total voltage of the measurement domain and the boost circuit (20V is normal), short-circuit the RX test point and the 1V8 test point between the first and second, and then run the program. Looking at the serial port log, if 0 chips are still found at this time, it will be one of the following situations:

a-1) Check the voltages at the test points 1V8 and 0V8 to see if they are 1.8V and 0.8V using a multimeter. If not, the two ASIC chips in this domain may not be soldered properly or the 1.8V, 0.8V LDO circuit may be abnormal. The majority of these issues are brought on by the short circuit of the 0.8V, and 1.8V SMD filter capacitors (measurement calculation of The resistance value of the chip filter capacitor related to the force plate).

a-2) Verify whether the circuits of U1, U2, and U5 are abnormal, such as a resistor with improper soldering, etc.

a-3) Check to see if the first chip has poorly soldered pins (it was discovered during maintenance that the pins were tinned from the side but were not at all tinned when the chip was removed).

b) The first chip and the prior circuit must both be in working order for one chip to be found in step a), and any additional chips are checked in a manner akin to that in which the first chip was found. Take the 38th and 39th chips, for instance, and short both the 1V8 test point and the RO test point. If the log can find 38 chips, there is no issue with the first 38; if 0 chips are still found, see if the 1V8 first is normal. After 38, there is a chip issue even if everything is normal. Dichotomize further until you locate the relevant chip. If the Nth chip has a problem, the N-1 chip can be located, but the 1V8 and RO between the Nth and N+1th chips can be located. A short circuit prevents the chip from being found in its entirety.

c) When the LCD displays ASIC 69: (reports 69), it means that the hash board can detect 69 chips at a frequency of 500M; after finding the corresponding chip position by the short-circuit method, first, check whether the test results are the same if they are the same, it means the chip Bad, need to replace the chip;

d) Method for maintenance: By short-circuiting the probe, short-circuit the 1V8 test point and the RX test point between chips 38 and 39 using the dichotomy method. If the log can locate 38 chips, then the first 38 chips are in perfect working order; if the log can only locate 46 chips and there are 47 short-circuited chips, then the 46th chip cannot be found and the appearance inspection is in perfect working order. Generally, the 47th chip can be replaced (you can also swap 46 and 47, if after swapping. If 46 chips are shorted and 45 is reported, it can be determined to be a chip problem, and the 46th chip should be replaced);

e) When the liquid crystal displays ASIC NG: (fixed to report a certain chip), it can be divided into the following two situations:

The value of the chip in the first scenario typically remains constant from test to test. In this situation, the maintenance procedure can be completed using the standard maintenance procedure of measuring the signal voltage.

Phenomenon 3: Incomplete Reply Nonce Data (PT2 Station)

PS: Special attention needs to be paid, the number of ASICs starts from 0, 000-069

Phenomenon 4: the Test Chip Test is OK, and the PT2 Function Displays PLUG OFF before TEST OVER.

The tester unplugs the cable before the voltage drops to zero as a result of a delay that the software sets during the test. The fixture must restart before testing.

The PT2 test environment must meet the following requirements: it must be between 20°C and 30°C in temperature. The software will halt the test when the outside temperature reaches 35°C.

Requirements for the PT2 test power supply: When the PT2 test fixture power supply is working with a load of 1500 watts (for example, when testing a board), the actual output voltage cannot be less than the 0.03V specified in the configuration file. (For example, if the configuration file requires trial production of 15V, then the output voltage of the power supply cannot be lower than 14.97V when it is loaded with 1500 watts)

Summary

In this post. we’ve covered:

• The single-board test detects that the chip is 0 (PT1/PT2 station)
• The single-board detection lack of chips (PT1/PT2 station)
• Incomplete reply nonce data (PT2 station)
• The PT2 function displays PLUG OFF BEFORE TEST OVER when the test chip test is successful.

This information ought to be useful to you. Please get in touch with us if you have any inquiries so that we can help.

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