Antminer S19j Pro Hashboard Repair Guide

Complete S19j Pro hashboard repair guide — BM1362 chip diagnostics, PIC vs noPIC identification, voltage domain testing, and chip replacement.

Overview

The Antminer S19j Pro delivers 100–104 TH/s using the BM1362 ASIC chip (5nm process). Each hashboard contains 126 BM1362 chips organized into approximately 42 voltage domains with 3 chips per domain. The target domain voltage is ~0.28V.

A critical distinction for the S19j Pro is that it comes in two hardware variants: PIC and noPIC. The PIC variant includes a PIC16F1704 microcontroller for board identification and I2C sensor bridging, while the noPIC variant eliminates this chip and uses direct sensor connections with a different enumeration method. Identifying your variant before beginning repair is essential.

Safety: Disconnect power and wait 60 seconds. Wear an ESD wrist strap at all times. The PSU delivers 12V at up to 255A.

Hashboard Specifications

Parameter	PIC Variant	noPIC Variant
ASIC Chip	BM1362 (5nm)	BM1362 (5nm)
Chips per Board	126	126
Voltage Domains	~42	~42
Chips per Domain	3	3
Core Voltage	0.28V ±0.02V	0.28V ±0.02V
PIC Chip	PIC16F1704 present	Not present
EEPROM	AT24C02D at 0x50	AT24C02D at 0x50
Temp Sensors	LM75A via PIC bridge	LM75A direct I2C
Hashrate/Board	~34 TH/s	~34 TH/s
Total Hashrate	100–104 TH/s	100–104 TH/s
Power	~3068W	~3068W

Identifying PIC vs noPIC

Before starting any repair, determine which variant you have:

How to identify:

Look for the PIC16F1704 — a 14-pin SOIC or TSSOP chip near the hashboard edge connector
The PIC is labeled "PIC16F1704" or has a Microchip logo
On the PCB, the PIC area has ICSP programming pads nearby

Repair implications:

PIC failures can prevent board detection
PIC reprogramming may be needed after EEPROM replacement
Temperature sensors are accessed through the PIC I2C bridge
Requires PICkit 3/4 for PIC-related repairs

How to identify:

The PIC16F1704 footprint on the PCB is empty (no chip soldered)
Or the footprint may not exist at all (different PCB revision)
Temperature sensors connect directly to the I2C bus

Repair implications:

Simpler architecture — one less component to fail
Temperature sensor issues are diagnosed directly on the I2C bus
EEPROM handles board identification without PIC intermediary
No PICkit programmer needed

Required Tools

Digital multimeter (0.01V resolution)
ESD wrist strap and mat
Hot air rework station (for BGA rework — BM1362 is BGA package)
Soldering iron with fine tip
Flux (Amtech NC-559-V2)
Solder wick (2mm)
99% isopropyl alcohol
Magnifying glass (10x–20x)
PICkit 3/4 programmer (PIC variant only)

Repair Procedure

Step 1: Visual Inspection

Remove the hashboard and inspect under bright light:

Focus areas specific to S19j Pro:
- The BM1362 BGA joints — look for signs of reflow (shiny vs dull)
- Buck converter regions between each 3-chip domain group
- Edge connector area — common corrosion point
- PIC chip area (PIC variant) — check for damage or missing chip
- EEPROM chip — verify AT24C02D is intact

Step 2: Voltage Domain Testing (42 Domains)

Each of the 42 domains powers 3 BM1362 chips at ~0.28V:

Resistance Check (Power Off):

Reading	Interpretation
3–12Ω	Normal (3 chips)
0–0.5Ω	Short circuit — shorted chip or capacitor
OL (open)	Broken connection

Powered Voltage Measurement:

Reading	Interpretation
0.26–0.30V	Normal
0V	Dead domain — failed regulator or shorted chip
0.32–0.40V	One or two chips open in domain
Fluctuating	Intermittent connection

The S19j Pro's 0.28V domain voltage is lower than the S19 Pro's 0.36V. Ensure your multimeter is on the 200mV or 2V range for accurate readings. On auto-ranging meters, the display should show millivolts.

Testing strategy for 42 domains: Start with a resistance sweep of all domains using the dichotomy method — check domains 1, 11, 21, 31, 42 first. This quickly identifies which section of the board has issues.

Step 3: Signal Chain Testing

The 126 BM1362 chips form a communication daisy chain:

Check CLK continuity from connector through the chain
Binary search for chain breaks — probe CI/RI at midpoint (chip #63)
With 126 chips, a binary search narrows to the exact chip in ~7 steps

S19j Pro-specific chain issues:

The BM1362's BGA joints are more sensitive to thermal cycling than QFN
Hair-thin cracks in BGA solder balls cause intermittent chain breaks
These are difficult to detect visually — may only show under thermal stress

Step 4: PIC and EEPROM Diagnostics

PIC16F1704 diagnostics:

Check I2C bus: SDA and SCL should read 3.3V when idle
Check PIC VDD: should be 3.3V
If the miner logs "PIC communication error," the PIC may need reprogramming
Use PICkit 3/4 connected to ICSP pads on the hashboard
Flash the correct hex file for S19j Pro PIC variant

EEPROM diagnostics:

EEPROM stores board serial number, calibration data, and chip map
"EEPROM read error" may indicate corrupted data or failed I2C communication
EEPROM can be read/written using a standard I2C programmer
If EEPROM data is corrupted, reprogram with correct board data

Direct I2C diagnostics:

Temperature sensors connect directly to the I2C bus
Check SDA/SCL pull-up resistors (4.7kΩ to 3.3V)
Verify sensor addresses: 0x48, 0x49, 0x4A, 0x4B
EEPROM at 0x50 can be accessed directly without PIC intermediary

EEPROM diagnostics: Same as PIC variant — stores board identification and calibration data.

Step 5: BM1362 Chip Replacement (BGA Rework)

The BM1362 uses a BGA package similar to the BM1368 in the S21:

Removal:

Apply generous flux around the target chip
Preheat to 150°C (2–3 minute soak)
Hot air at 350–380°C, medium airflow
Chip releases in 60–90 seconds
Lift straight up with vacuum tweezers

Pad cleaning:

Apply flux to exposed pads
Clean with solder wick at 350°C
Wipe with IPA
Pads should be flat with thin solder coating

Installation:

Inspect replacement chip solder balls
Apply flux to PCB pads
Align chip with orientation marker
Reflow with hot air (preheat 150°C, then 350–380°C)
Allow gradual cooling
Clean flux with IPA
Inspect alignment under magnification

Step 6: Verification

Domain resistance check — repaired domain should read 3–12Ω
Powered voltage test — all 42 domains at 0.26–0.30V
Install in miner and verify:
- All 126 chips detected
- Hashrate ~34 TH/s per board
- Temperature readings normal (PIC variant: via PIC bridge; noPIC: direct)
24-hour burn-in for stability

# Verify repair via SSH
ssh root@<miner-ip>
cat /tmp/freq.txt     # 126 chips with frequency
cat /tmp/temp.txt     # Temperature sensor readings
dmesg | grep -i pic   # PIC status (PIC variant)

Common Failure Patterns

Symptom	Likely Cause	Fix
"Chain find 0 ASIC"	First chip dead, connector issue	Check chip #0, reseat connector
"PIC communication error"	PIC failure (PIC variant)	Reprogram or replace PIC
"EEPROM read error"	Corrupted EEPROM data	Reprogram EEPROM
Domain at 0V	Shorted BM1362 or failed regulator	Test chip resistance, replace if shorted
Intermittent chip drops	BGA joint failure from thermal cycling	Reflow suspect chips
Temp reading -1	Sensor or I2C failure	Check sensor, pull-ups, PIC (if applicable)
Lower hashrate than expected	Degraded chips or multiple weak domains	Test all domains, replace weak chips

Troubleshooting FAQ

What is the difference between PIC and noPIC S19j Pro boards?

The PIC variant has a PIC16F1704 microcontroller that bridges I2C communication to temperature sensors and manages board identification. The noPIC variant connects sensors directly to the I2C bus. Both produce the same hashrate. The noPIC variant is simpler to repair as it has one less potential failure point.

S19 Pro Hashboard Repair — BM1398-based S19 variant
S19 XP Hashboard Repair — BM1368-based high-performance S19
S19 Series Common Issues — cross-model issues
BM1362 ASIC Chip Reference
Soldering Techniques — BGA rework details