Antminer S9 Hashboard Repair Guide

Step 1: Visual Inspection

The S9 has been in service for years, so age-related issues are common:

• Oxidation and corrosion — especially on boards from humid environments. Green or white deposits on copper traces and component leads.
• Darkened domains — overheated regulator areas (16nm chips run warmer than newer nodes)
• Connector wear — the S9's 18-pin connector accumulates oxidation over years of use
• Degraded capacitors — small ceramic capacitors near regulators may show cracks from thermal cycling
• PIC chip area — check the PIC16F1704 and surrounding I2C components
• Bent or broken heatsink clips — S9 heatsink retention clips fatigue over time

Step 2: Voltage Domain Testing (21 Domains)

Each of the 21 domains powers 3 BM1387 chips at ~0.40V:

Resistance Check (Power Off):

Powered Voltage Measurement:

S9 domain testing is straightforward due to the simple 3-chips-per-domain architecture. Each domain is independent — a failed domain does not typically affect neighbors (unlike the S17).

Step 3: Signal Chain Testing

63 BM1387 chips in the chain:

1. Binary search at chip #32 (midpoint)
2. ~6 steps to isolate the break
3. CLK, CI, RI signals at 1.8V levels

Common S9 chain issues:

• Corroded trace near board edge (years of moisture exposure)
• Cold solder joint on QFN chip from thermal cycling
• Failed first chip (chip #0) — causes "chain find 0 ASIC"

Step 4: PIC and EEPROM Diagnostics

The S9 PIC16F1704 operates the same way as in the S19 series:

1. I2C bus check: SDA and SCL at 3.3V when idle
2. PIC VDD: 3.3V
3. EEPROM at 0x50: readable via I2C

S9-specific PIC notes:

• The PIC address can shift between 0x20–0x27 across power cycles
• PIC hex files are S9-specific — do not use S19 hex files
• After years of service, EEPROM data may degrade, requiring reprogramming

PIC reprogramming:

1. Connect PICkit 3 to ICSP pads
2. Flash with S9-specific hex file
3. Verify board detection after reprogramming

Step 5: BM1387 Chip Replacement (QFN — Beginner-Friendly)

The BM1387's QFN package is the easiest ASIC chip to rework:

Removal with soldering iron only (no hot air needed):

1. Apply generous flux around all four sides
2. Heat one side of the chip with the soldering iron, gently lifting that edge
3. Move to the opposite side and repeat
4. Alternate sides until the chip lifts free
5. This "rock and lift" method works well for QFN chips

Removal with hot air (faster):

1. Apply flux
2. Preheat to 120°C (lower than newer chips due to simpler board)
3. Hot air at 320–350°C
4. Chip releases in 30–45 seconds

Installation:

1. Clean pads with solder wick and IPA
2. Apply thin solder paste layer to pads (or tin pads with iron)
3. Place new BM1387 — match the orientation dot
4. Reflow with hot air at 320–350°C (~30 seconds)
5. Clean flux with IPA

Step 6: Verification and Testing

1. Domain resistance check — 4–15Ω on repaired domain

2. Powered voltage test — 0.38–0.42V all domains

3. Test fixture method (recommended for S9):

   • S9 test fixtures are widely available and affordable
   • Connect the hashboard to the test fixture
   • The fixture emulates the control board and tests all 63 chips
   • Much faster than installing in the miner for each test

4. Full miner test:

   • Install in miner, connect power and data
   • All 63 chips detected
   • Hashrate ~4.5 TH/s per board
   • Temperature normal

ssh root@<miner-ip>
cat /tmp/freq.txt    # 63 chips per board
cat /tmp/temp.txt

5. 24-hour burn-in for stability confirmation