​Welcome to Peak Asic's S19K Pro Hashboard repair guide! We specialize in providing expert Antminer hashboard repairs, but we understand that some of you might want to try repairing your devices yourself. To support your efforts, we've created this comprehensive guide to help you through the process. Follow the steps below, and feel free to reach out to us if you need professional assistance or would like to send in miners for repair.

 I. Preparation for Maintenance: Platform, Tools, and Equipment

 1. Platform Requirements:
- **Anti-static repair workbench:** Must be grounded to prevent static damage.
- **Anti-static wrist strap:** Ensure proper grounding.

 2. Equipment Requirements:
- **Thermostatic soldering iron:** Set between 350°C and 380°C with a fine tip for precision work on small SMD resistors and capacitors.
- **Hot air gun and BGA rework station:** Essential for removing and soldering chips/BGAs.
- **Multimeter:** Preferably Fluke, equipped with heat-shrink-covered steel needles for accurate measurement.
- **Oscilloscope and Ethernet cable:** Ensure a stable Internet connection.

 3. Testing Tool Requirements:
- **APW12 power supply and power adapter cable:** Use thick copper wires (4AWG, within 60cm) to connect the positive and negative terminals of the power supply to the hash board. This is specifically for PT1 and repair testing.
- **Test fixture:** Utilize V2.1 or V2.3 control boards (test fixture part number ZJ0001000004). The positive and negative terminals of the test fixture's power supply need to have discharge resistors installed, recommended 20 Ohm, 100W or higher cement resistors.

 4. Auxiliary Materials and Tools for Maintenance:
- **Solder paste, flux, and board cleaner:** Use anhydrous alcohol for cleaning flux residues after repairs.
- **Thermal conductive silicone grease:** Apply on the chip surface after repairs.
- **Reballing stencil:** Sized for 6mm*7mm chips, and desoldering braid for cleaning up old solder.
- **Chip soldering:** Pre-tin new chip pins before soldering them to the hash board. Apply thermal conductive gel evenly on the chip surface before securing the heatsink.

 5. Common Spare Parts for Maintenance:
- **0402 Resistors:** 0R, 33R, 51R, 10K, 4.7K.
- **0402 Capacitors:** 0.1uF, 1uF.
- **SMD Resistor, 33Ω, 1%, 1/20W, R0201 (0603).**
- **Resistor, 10K, +/-1%, 1/16W, 0402.**
- **Resistor, 0Ω, 5%, 1/16W, 0402.**
- **SMD Ceramic Capacitor, 100NF, 6.3V, 10%, X5R, C0201 (0603).**

 II. Repair Requirements

 1. Chip Replacement:
- Employ precise techniques to avoid PCB deformation. Ensure no components are missing, and check for open or short circuits around the replaced parts.

 2. Personnel Expertise:
- Repair technicians should have a solid understanding of electronics, with over a year of experience in repairing BGA/QFN/LGA packages.

 3. Post-Maintenance Testing:
- Ensure the hash board passes at least two tests before considering it repaired.

 4. Tool and Test Fixture Functionality:
- Verify that all tools and test fixtures are functioning correctly. Confirm the parameters of the repair station's test software and test fixture versions.

 5. Chip Testing:
- Begin with PT1 chip detection before moving to functional testing. Ensure the BSM radiator is properly soldered before performing PT3 tests. Use the chassis for effective heat dissipation by placing two hash boards to create an airflow channel.

 6. Signal Measurement:
- Utilize four fans for cooling during signal measurements, operating them at full speed.

 7. Power Connection Order:
- Connect the negative power cable first, then the positive, and finally the signal ribbon cable. Reverse this order during disassembly to avoid damaging components like U1 and U2.

 8. New Chip Soldering:
- Pre-tin the pins of new chips before soldering them onto the PCBA. Evenly apply thermal gel on the chip surface before securing the heatsink.

 9. Test Modes:
- Use Test_Mode and scan mode for all repair tests. After passing these tests, normal assembly and aging processes should begin from the first test station.

 10. Heaksink Removal:
- For the BHB56902 model, remove heatsinks using a hot air gun at 400°C, heating for 15 seconds. This will allow the heatsinks to be detached before soldering the chip using conventional methods.

 11. Flux Cleaning:
- Thoroughly clean the chip surface of any residual flux after repairs to ensure proper soldering during the BSM process.

 III. Test Fixture Fabrication and Precautions

- Ensure the test fixture provides adequate cooling for the hash board and facilitates easy signal measurement.

 1. Part Number:
- Use ZJ0001000004 Test fixture.

 2. FPGA Updates:
- Update the FPGA on the test fixture control board using an SD card. Insert the SD card into the slot, power on, and wait for the control board indicator light to flash twice, three times to complete the update.

 3. Test SD Card Creation:
- For PT1 repairs, create an SD card with the PT1 program. Delete the default config.ini file and conduct testing via scanning. Provide cooling to the PCBA during measurements to prevent overheating.

 IV. Overview of Principles

 1. BHB56902 Hash Board Working Structure:
- The hash board features 77 BM1366BS chips in 11 groups (domains) with 7 ICs each. The chips operate at a domain voltage of about 1.15V. Groups 10 and 11 are powered by 19V from the boost circuit U178 to MP2019, which powers LDOs to produce 1.2V and 0.8V for these domains. The remaining domains receive power from the previous domain's voltage, also outputting 1.2V and 0.8V.

### 2. Temperature Circuit:
- Two temperature sensors on the BOT side, located at the air inlet and outlet, are powered by 3.3V and connected via the I2C bus SCL, SDA. Troubleshoot temperature issues by identifying the problematic sensor location.

 3. Comparison with 42612 Model:
- The BHB56902 hash board includes 10 level shifters for signal addition, used from the second domain onward.

 4. Chip Cooling:
- Each 1366 chip has its own heatsink, which must be properly soldered on both sides for effective cooling.

 5. Signal Routing:
- **CLK (XIN) Signal:** Generated by the Y1 25MHz crystal oscillator, travels from chip 01 to chip 77.
- **RST Signal:** Enters from pin 3 of the IO port, travels from chip 01 to chip 77.
- **CI Signal:** Enters from pin 7 of the IO port, travels from chip 01 to chip 77.
- **RX (RI, RX) Signal:** Travels from chip 77 to chip 01.
- **BO (BI, BO) Signal:** Travels from chip 01 to chip 77.

 6. Overall Architecture:
- Composed of three hash boards, one control board, an APW121215 power supply, and four cooling fans (26000 RPM + 27000 RPM).

 V. Common Hash Board Faults and Troubleshooting Steps

 1. Symptom: Single Board Test Detects 0 Chips (PT1/PT3 Station)
- **Step 1:** Check power supply output.
- **Step 2:** Verify voltage domain output; measure the output at the hash board's power terminals.
- **Step 3:** Inspect the boost circuit output at test points C56, 57, which should show 19-20V.
- **Step 4:** Verify the 1.2V or 0.8V output from each LDO group.
- **Step 5:** Check the chip signal outputs (CLK/CI/RI/BO/RST). Compare measurements with adjacent groups if there are significant deviations.

### 2. Symptom: Incomplete Chip Detection on Single Board (PT1/PT3 Station)
- **a)** If ASIC NG: (0), measure the domain voltage and check the boost circuit's 20V output. Use a short circuit probe to test RX and 1V2 between the first and second chips.
- **a-1)** Measure the diode or impedance of the 1V2 and 0.8V LDO circuits.
- **a-2)** Check U5 circuit for issues like cold solder joints.
- **a-3)** Look for short circuits caused by solder bridging near the chip.
- **a-4)** Verify that the first chip’s pins are properly soldered.
- **b)** If one chip is found, use a binary search method to troubleshoot subsequent chips.
- **c)** If ASIC NG reports a specific chip, measure signal voltages and inspect for potential issues like faulty resistors. 

 3. Symptom: Single Board Pattern NG (PT3 Station)
- Replace chips with significant characteristic differences or insufficient solder on the BSM surface. Swap low response rate chips with high response rate chips to identify and replace faulty ones.

 4. Symptom: B_A X PCS (X Chips Insufficient Response)
- Swap chips with higher response rates from other domains to diagnose and replace faulty chips.

 5. Symptom: Chip Testing OK, But PT3 Function Test Serial Port Does Not Stop (Continuous Running)
- Use a short circuit probe to find the faulty chip causing continuous running during

 PT3 testing.

 6. Chip Address Error (PT3)
- Replace the chip reporting the address error.

 7. Single Board OK, Whole Machine Hash Rate Drops
- Replace chips with erratic RX responses or unstable domain LDO power supplies. Perform low-frequency Debug measurements on main chip signals to identify and address soldering issues or faulty chips.

 VI. Control Board Issues and Solutions

 1. Entire Machine Does Not Run
- **Step 1:** Check voltage output points and replace corresponding ICs for 3.3V short circuits.
- **Step 2:** Inspect the soldering condition of DDR/CPU (use X-RAY inspection on the production side).
- **Step 3:** Update the flash program with an SD card.
- **Step 4:** After successful flashing, power off and restart, then wait 30 seconds to enable OTP.

 2. Machine Cannot Find IP
- Check the network port, transformer T1, and CPU for soldering issues.

 3. Machine Cannot Upgrade
- Inspect the network port, transformer T1, and CPU for soldering issues.

 4. Machine Fails to Read Hash Board or Misses Connections
- Check the condition of ribbon cable connections. Inspect control board chain components and examine the quality of wave soldering.

## VII. Whole Machine Fault Symptoms

### 1. Initial Testing of the Whole Machine
- Common symptoms include inability to detect IP, abnormal fan count detection, and chain detection anomalies. Repair based on monitoring interface and test LOG prompts.

 2. Aging Test
- **Fan Display Abnormal:** Check fan operation and connections.
- **Missing Chain:** Inspect ribbon cable connections and perform PT1/PT3 testing on single boards.
- **Temperature Anomaly:** Ensure PCB temperature does not exceed 75°C and chip temperature does not exceed 95°C. Check fan speed and temperature sensors for issues.
- **Incomplete Chip Detection in Whole Machine:** Dismantle and retest with PT1.
- **No Hash Rate After Running for Some Time:** Check the network connection.
- **Normal Conditions During Aging Test:** Monitor the status of good machines during the aging test.

 VIII. Other Notes

 Repair Flow Chart:
1. **Visual Inspection:**
   - Inspect the hash board for any visible issues like PCB deformation or scorch marks. Address any problems before proceeding.

2. **Impedance Testing:**
   - Test the impedance of each voltage domain to detect short circuits or open circuits. Resolve any issues found before continuing.

3. **Voltage Testing:**
   - Verify that each domain's voltage is around 1.15V.

4. **Chip Detection:**
   - Use a test fixture to detect chips and diagnose based on the results.

5. **Signal Direction:**
   - Follow the signal directions to identify abnormal fault points. RX signal travels in reverse (chip 77 to 1), while signals like CLK, CI, BO, and RST travel forward (chip 1 to 77).

6. **Re-Soldering:**
   - Apply flux around the chip, heat each solder point until it melts, allowing the chip pins to reflow and solder to the pad. If the issue persists after re-soldering, replace the chip.

7. **Post-Repair Testing:**
   - Test the hash board twice to confirm it is OK. Record all maintenance and analysis results.

8. **Document Recording:**
   - Maintain detailed repair/analysis records for feedback to production, after-sales, and R&D.

9. **Routine Aging Tests:**
   - Reassemble the repaired hash boards into a complete machine for routine aging tests. Ensure all repaired items re-enter the production line starting from the first station to maintain quality continuity.