How to fix the Antminer L7 temperature reading error?

The temperature sensor chip of the Antminer L7 was faulty and read incorrect temperatures during the operation of the ASIC miner. How to quickly repair the temp sensor failure of Antminer L7 hash board to restore the normal profit of miners?

This article will introduce two faults: L7 hash board temperature reading error and single board temperature sensor chip failing to reach the standard value, so as to explore in depth how to fix the L7 hash board temperature fault and resume normal mining.

Failure Analysis

I.Hash board temperature reading error

The kernel log reports "read temp error! Pcb temp count 2 chip temp count 2 uneffective value count 0", indicating that the three hash boards of Antminer L7 have temperature reading errors.

Troubleshooting and solutions:

1. Use the Antminer universal chip testing fixture to test the three hash boards separately. During this testing process, we can use the Antminer tester voltage regulating board instead of the original power supply. The method is as follows.

• Insert one end of the 4pin voltage regulation cable into the test fixture interface, and connect the other end to interface ③ of the voltage regulation board;

• Insert the voltage regulation board cable into the test fixture;

• Insert the 6Pin power cable into the test fixture;

• Connect one end of the ribbon data cable to the fixture;

• Insert one end of the USB to TTL cable into the fixture and connect the other end to the computer;

• First, power on the test fixture to allow it to complete self-testing;

• After completing the self-test, use the red and black alligator clips to clamp the positive and negative terminals of the hash board and regulated PSU respectively;

• Finally, insert the other end of the data cable into the hash board;

• After connecting all cables, press the test button to start testing the hash board.

Example diagram (for reference only)

Click the Universal testing fixture usage tutorial video to learn more.

2. Identify the temperature sensor chip fault based on the test results:

• Locate the corresponding faulty temperature sensor chip number. (The two temperature sensor chips at the air inlet are models T451 and TMP75, and the two at the air outlet are also models T451 and TMP75.)

• According to the working principle of the temperature sensing circuit, first check the voltage of the relevant pins of the temperature sensor chip. If a voltage anomaly is detected in any of the temperature sensor chips, replace that specific chip with another of the same model. If the voltage is normal, then check the quality of the resistors connected to the pins of the temperature sensor chip. If the resistance value is abnormal, find a resistor with the same specifications and resistance value and replace it.

Ⅱ. The temperature sensing chip of a single board does not reach the standard value

The Antminer L7 hash board has four temp sensor chips. Through the PicoBT test fixture, it was found that the temperature of one of them was 1°C, which did not meet the standard value.

Troubleshooting steps

1. First, use a multimeter to verify that resistors R1381, R1382, R1383, and R1384 are functioning correctly. When measuring resistance, offline testing is required to ensure accurate resistance results. The correct resistance values of resistors R1381 and R1382 are 4.7K, and the correct resistance values of resistors R1383 and R1384 are 100R.

2. Through the above troubleshooting, if the resistance value of the resistor is correct. We need to check whether the temp sensing chip U253 has poor soldering. If there is no poor soldering problem, replace the faulty temperature sensing chip directly. After replacement, use the test fixture to test the hash board and find that the temp display still reads 1°C, which does not meet the standard operating temperature requirements for miners.

3. We resolder the temp sensing chip model S75 to the hash board. Use the test fixture to retest and confirm that the temperature of the temp sensing chip has returned to normal. The repair is successfully completed.

If you need assistance with the repair of the hash board of Antminer L7 and are interested in learning relevant repair skills, please click here to view more details.

A malfunction in the temperature sensor chip can prevent the ASIC miner from monitoring the operating temperature in real time. To ensure accurate monitoring of the Antminer L7's temperature, it is recommended to conduct troubleshooting according to the aforementioned methods.