Antminer S19j Pro (noPIC) Maintenance & Repair Guide

Introduction

The Bitmain Antminer S19j Pro noPIC is not just another mining variant — it is an entirely different animal hiding inside a familiar chassis. On the surface, it looks identical to a standard S19j Pro: the same enclosure, the same fan configuration, the same APW12 power supply, and the same ~104 TH/s of SHA-256 hashrate at roughly 3068 W. But crack open the hashboard and you will find a fundamentally different voltage regulation architecture — one where the PIC16F1542 programmable interface controller has been removed from the design entirely.

The “noPIC” designation refers to hashboards manufactured without the PIC (Programmable Interface Controller) chip that is present on standard S19j Pro boards. On a conventional S19j Pro hashboard, the PIC16F1542 microcontroller stores calibration data, serial identification, voltage trim parameters, and temperature sensor configuration in its internal EEPROM. During boot, the control board’s firmware reads this PIC data to initialize voltage domains and configure chip operating parameters. On noPIC boards, this entire subsystem is absent. Voltage regulation is handled through fixed resistor configurations and direct register writes from the control board firmware during initialization, bypassing the PIC-mediated calibration loop entirely.

Why does this matter for maintenance and repair? Because nearly every diagnostic and repair procedure that touches voltage regulation, chip initialization, temperature sensing, or board identification is different on a noPIC board compared to its PIC counterpart. If you follow a standard S19j Pro repair guide on a noPIC board, you will misdiagnose problems, chase phantom failures on components that do not exist, and potentially damage a perfectly repairable board. This guide exists to prevent exactly that.

What Does “noPIC” Actually Mean?

To understand the noPIC modification, you need to understand what the PIC chip does on a standard board and what replaces its function when it is removed.

On a standard S19j Pro hashboard:

• The PIC16F1542 microcontroller sits on the hashboard and stores calibration data in its internal EEPROM — voltage trim values, board serial number, chip frequency parameters, and temperature sensor offsets.
• During boot, the control board firmware communicates with the PIC via I2C bus to read this calibration data before initializing the voltage domains.
• The PIC acts as a gatekeeper: if the firmware cannot read valid data from the PIC, the hashboard will not initialize. This is Bitmain’s hardware-level DRM mechanism — it ties specific calibration profiles to specific boards.
• The PIC also manages the temperature sensor circuit, providing calibrated temperature readings to the control board.

On a noPIC S19j Pro hashboard:

• The PIC16F1542 chip location is unpopulated (empty pads) or the chip is physically removed.
• Voltage regulation is handled through fixed resistor divider networks that set static voltage levels, rather than dynamically adjustable trim values stored in the PIC.
• Board initialization relies on the EEPROM (AT24C02) chip to store serial and identification data, with the control board firmware writing default voltage parameters directly during boot.
• Temperature sensing is routed through a simplified circuit path that does not pass through the PIC — typically using direct NTC thermistor readings or a dedicated temperature sensor IC.
• Compatible firmware handles the absence of the PIC by using predefined voltage tables instead of PIC-stored calibration profiles.

How to Identify a noPIC Board

Before you begin any maintenance or repair, you must confirm whether your S19j Pro hashboards are PIC or noPIC. Using the wrong procedures can cause misdiagnosis or damage. Here are the identification methods, in order of reliability:

1. Physical inspection (most reliable): Remove the hashboard from the chassis and locate the PIC chip position. On the standard S19j Pro, the PIC16F1542 is a small 14-pin TSSOP package typically labeled U5 or U6 (position varies by board revision). On a noPIC board, this location will show either empty solder pads or a depopulated footprint where the chip was removed. Some noPIC boards have a small ink marking or sticker near the PIC location indicating the modification.
2. Firmware logs (reliable): SSH into the miner and check the kernel log. On a PIC board, you will see PIC initialization messages. On a noPIC board, the log will show either PIC not detected messages or will skip PIC initialization entirely, going straight to EEPROM-based configuration.
3. Web dashboard: Some firmware versions display the hashboard type in the chain details. Look for “noPIC” or “NP” designations in the hashboard hardware version string.
4. Purchase documentation: If you bought the miner from D-Central or another reputable dealer, the product listing or invoice should specify whether it is a PIC or noPIC variant.

Technical Specifications

The noPIC S19j Pro shares the majority of its specifications with the standard S19j Pro. The differences are concentrated in the voltage regulation and initialization subsystem. Know where the two diverge — that is where your maintenance procedures must change.

noPIC vs. Standard PIC — Critical Differences

This is the table that matters most. Every difference listed here translates directly into a different maintenance or repair procedure. Bookmark this section — you will reference it repeatedly.

Before You Begin

Safety Warnings

Summary of safety rules:

1. Power off and unplug before any maintenance. Wait 5 minutes for capacitor discharge.
2. Wear an ESD wrist strap grounded to the miner chassis whenever handling hashboards.
3. Let the miner cool for 10+ minutes after shutdown before touching heatsinks.
4. Work in a clean, dry environment — no liquids near the miner, no metal shavings, no conductive debris.
5. Never operate the miner with the cover removed — airflow direction is critical for cooling all four hashboards.
6. Follow the power connection sequence — negative first on, negative last off.
7. Photograph everything — document cable positions, connector orientations, and the voltage divider area before touching anything.
8. Never assume PIC procedures apply — if a troubleshooting step references PIC chip programming, reprogramming, or PIC EEPROM, it does not apply to your noPIC board.

Routine Maintenance

Prevention is cheaper than repair — and it is even more critical on noPIC boards where the voltage regulation lacks the dynamic adjustment capabilities of PIC-equipped models. A noPIC board running on fixed resistor dividers depends entirely on clean power, stable temperatures, and unobstructed airflow to deliver the voltage precision its 504 BM1362 chips demand. Let dust accumulate, let fans degrade, let thermal gel dry out, and you are asking those fixed voltage networks to operate outside their design margins.

Recommended Maintenance Schedule

Visual Inspection

A thorough visual inspection catches problems before they become failures. On noPIC boards, pay special attention to the areas described below.

External inspection (no disassembly required):

• Fan blades: Shine a flashlight through the intake and exhaust fans. Look for dust accumulation on blades, cracked blades, or objects lodged in the fan housing. A single cracked blade creates vibration that accelerates bearing wear across all fans.
• Intake/exhaust grills: Check for dust mats forming at the intake. A clogged intake starves all four hashboards of cooling air simultaneously. In Canadian winters with forced-air heating systems, airborne dust loads increase dramatically.
• Ethernet and power connections: Verify the Ethernet cable is firmly seated. Check the C13/C14 power connection at the PSU — a loose connection causes intermittent power drops that trigger reboots.
• Physical damage: Check the chassis for dents, bent fins, or shipping damage. A dented chassis can restrict airflow or short-circuit hashboard components against the metal enclosure.

Internal inspection (top cover removed):

• Hashboard ribbon cables: Check all four ribbon cable connections at both the hashboard end and the control board end. These cables are the most common point of intermittent failure — vibration from fans can gradually work connectors loose over months of operation.
• Heatsink condition: Look for heatsink displacement, bent fins, or thermal gel squeeze-out. On the S19j Pro, each hashboard has heatsinks on both sides — inspect both the top and bottom surfaces.
• PCB condition: Look for discoloration (brown or dark spots indicating overheating), white residue (flux or corrosion), or component damage (cracked capacitors, lifted pads).
• noPIC-specific: Voltage divider area: Locate the voltage regulation section of each hashboard (typically near the power input connectors). Look for discolored or darkened resistors, solder joint cracks on the small 0402 components, or any sign of localized overheating. On noPIC boards, a shifted resistor value in the voltage divider network changes the voltage delivered to an entire chip domain.
• EEPROM chip area: Locate the AT24C02 EEPROM on each hashboard. Check for physical damage, cracked packages, or cold solder joints. This chip stores the board identification data that replaces the PIC function.

Cleaning Procedures

Dust is the number one enemy of ASIC miner longevity. The S19j Pro pulls approximately 200+ CFM of air through its chassis continuously. Every particle in that air has a chance of settling on a heatsink fin, fan blade, or PCB surface. Over time, dust accumulation reduces cooling efficiency, increases chip temperatures, and accelerates thermal gel degradation.

Monthly external cleaning:

1. Power off the miner and unplug from wall power. Wait 5 minutes.
2. Use compressed air (or electric blower) to clear the intake and exhaust grills. Blow from inside out (exhaust direction) to push accumulated dust out of the miner rather than deeper in.
3. Blow out the fan blades with short, controlled bursts. Hold the fan blade stationary with a finger to prevent the fan from spinning during cleaning — compressed air spinning a fan generates back-EMF that can damage the fan controller circuit on the control board.
4. Wipe down the external chassis with a dry lint-free cloth.

Quarterly deep cleaning:

1. Power off, unplug, and wait 10 minutes for full cool-down.
2. Remove the top cover (typically 4-6 Phillips screws along the top edge).
3. Wearing an ESD wrist strap, use compressed air to blow out all internal surfaces — heatsink fins, PCB surfaces, cable areas, and the control board.
4. Use a soft nylon anti-static brush to dislodge any compacted dust between heatsink fins. Canadian environments with high humidity can cause dust to cake and harden — compressed air alone may not remove it.
5. Inspect all four hashboard ribbon cable connections while the cover is off. Reseat any that feel loose.
6. Replace the cover and all screws before powering on.

Thermal Gel Replacement

The thermal conductive gel between BM1362 chips and the aluminum heatsinks is critical for heat transfer. On the S19j Pro, each hashboard has 126 chips, each requiring proper thermal interface contact. When thermal gel degrades, individual chips or chip groups overheat, causing hashrate drops, hardware errors, and eventually thermal shutdown.

Signs that thermal gel needs replacement:

• Chip temperatures have risen 5–10°C compared to when the miner was new (at same ambient temperature and fan speed)
• Individual chips run significantly hotter than their neighbors (visible in the dashboard’s per-chip temperature display, if your firmware supports it)
• Thermal throttling occurs despite clean heatsinks and working fans
• The miner has been running continuously for 12–18 months without thermal maintenance

Thermal gel replacement procedure:

1. Power off, unplug, wait 10+ minutes for full cool-down. Wear ESD protection.
2. Remove the hashboard from the chassis (document cable positions with photos first).
3. Carefully remove the heatsinks — they are typically held by spring clips or screws. Do not pry against the PCB.
4. Clean old thermal gel from both the chip surfaces and heatsink surfaces using 99% IPA and lint-free cloths. Remove all residue.
5. Apply fresh thermal conductive gel evenly across each chip surface. Use enough to ensure full contact but not so much that it squeezes out and bridges adjacent components.
6. Reseat the heatsinks, ensuring even pressure distribution.
7. Reinstall the hashboard, reconnect cables (follow the power connection sequence), and test.

Fan Maintenance

The S19j Pro uses four fans — two intake and two exhaust — to maintain airflow across all four hashboards. Fan failure or degradation directly impacts cooling capacity and, on noPIC boards with their fixed voltage regulation, thermal excursions are handled less gracefully than on PIC boards that may have dynamic voltage adjustment capabilities.

Fan health indicators:

• Normal: Consistent RPM within ±10% of the fan’s rated speed. Smooth, even sound.
• Degrading: RPM fluctuations, intermittent grinding or clicking sounds, one fan running noticeably slower than its pair.
• Failed: Zero RPM reported, fan not spinning, or loud grinding/scraping. The miner’s firmware will typically trigger an alarm or shutdown when a fan fails.

Fan replacement procedure:

1. Power off and unplug the miner. Note which fan position is being replaced (front-left, front-right, rear-left, rear-right).
2. Remove the fan guard (if present) and disconnect the fan cable from the control board fan header.
3. Remove mounting screws (typically 4 per fan) and slide the old fan out.
4. Install the replacement fan. Verify airflow direction — intake fans blow air into the chassis, exhaust fans pull air out. Arrow markings on the fan frame indicate airflow direction. Getting this wrong means two fans fighting each other instead of working together.
5. Connect the fan cable to the correct header on the control board.
6. Power on and verify the new fan’s RPM in the dashboard. It should match the other fan in the same pair within ±10%.

Diagnostics & Troubleshooting

Diagnosing a noPIC S19j Pro requires understanding what is different about its initialization sequence and what error messages mean in the context of a board without a PIC chip. Many standard Antminer troubleshooting guides send you looking for PIC-related problems that cannot exist on your board. This section gives you the correct diagnostic procedures for noPIC hardware.

LED Indicators

The S19j Pro control board has LED indicators that provide quick status information without needing to access the web dashboard or SSH:

SSH Diagnostic Commands

SSH access is your most powerful diagnostic tool. Connect to your miner via SSH to access detailed logs, real-time performance data, and hardware status that the web dashboard does not expose.

# Connect to miner (default credentials: root / root — CHANGE THESE)
ssh root@MINER_IP_ADDRESS

# Check firmware version and build type (look for "noPIC" designation)
cat /etc/bitmain-release

# View kernel log for hashboard initialization (noPIC boards skip PIC init)
dmesg | grep -i "chain|hash|pic|eeprom|voltage"

# Check real-time miner status — all 4 chains should show
cat /dev/chainInfo 2>/dev/null || cgminer -T

# View cgminer/bmminer log for chip detection on all 4 hashboards
tail -200 /var/log/messages | grep -i "chain|asic|chip|noPIC"

# Check chip temperatures across all 4 boards
cat /dev/temp 2>/dev/null

# Monitor hashrate and hardware errors in real-time
watch -n 5 'cat /dev/hashrate 2>/dev/null; echo "---"; cat /dev/hwErrors 2>/dev/null'

# Check EEPROM status (noPIC boards rely on EEPROM for board ID)
dmesg | grep -i "eeprom|at24|i2c"

# Verify voltage domain readings (noPIC uses fixed dividers)
cat /dev/voltage 2>/dev/null

# Check fan speeds (all 4 fans should report)
cat /dev/fan 2>/dev/null

# Network diagnostics
ping -c 3 8.8.8.8
ping -c 3 stratum.slushpool.com

# Check system uptime and load
uptime

# Check filesystem for corruption
df -h

Common Error Codes — noPIC Interpretation

Many error codes are shared between PIC and noPIC variants, but their root causes and troubleshooting paths differ. Here is how to interpret common errors on a noPIC board:

Hashboard Testing — noPIC Procedure

Testing a noPIC hashboard on a test fixture requires the test fixture to be configured for noPIC boards. Using a PIC-configured test fixture on a noPIC board will produce false failures because the fixture looks for a PIC handshake that will never come.

Test fixture setup for noPIC:

1. Ensure the test fixture software is set to noPIC mode (or “universal” mode if available). On Bitmain’s V2.3 test fixture, this is typically a configuration file setting.
2. Connect the hashboard following the power connection sequence: negative first, positive second, signal cable last.
3. The test software should detect the board type automatically via EEPROM data. If prompted, select the noPIC S19j Pro profile.
4. Run the PT1 chip test — this verifies that all 126 chips on the hashboard are detected and responsive via the signal chain. The PT1 test on noPIC boards skips the PIC validation step and proceeds directly to chip enumeration.
5. If PT1 passes (all 126 chips detected), run the PT2 functional test — this sends work to all chips and verifies they return valid nonces.
6. Both PT1 and PT2 must pass. After the first pass, let the board cool for a few minutes, then test again. Two consecutive passes constitute a successful test.

noPIC Voltage Regulation Deep Dive

This section is the technical heart of what makes the noPIC S19j Pro different. Understanding the voltage regulation architecture is essential for diagnosing the most common and confusing failures unique to noPIC boards.

Voltage Divider Architecture

On a standard PIC S19j Pro, the PIC16F1542 stores voltage trim values that the firmware reads to set precision voltage for each domain. If a domain drifts slightly, the PIC data allows firmware-mediated correction. On the noPIC board, this dynamic adjustment mechanism is replaced with fixed resistor divider networks.

Each voltage domain on the noPIC hashboard is set by a pair of precision resistors forming a voltage divider from the buck converter’s feedback pin to ground. The ratio of these two resistors determines the output voltage of that domain. The target voltage for each domain is approximately 0.32V, and the resistor values are selected during manufacturing to achieve this target within a tight tolerance.

What this means for repair:

• If a voltage divider resistor drifts in value (due to thermal stress, age, or damage), the domain voltage changes. A higher voltage over-stresses chips. A lower voltage under-powers chips, causing detection failures or low hashrate.
• Unlike PIC boards where firmware can compensate for small voltage drifts via PIC-stored trim data, noPIC boards have zero dynamic compensation. The voltage is whatever the resistors dictate.
• When measuring voltage domains on a noPIC board, any reading outside ±5% of the expected 0.32V (i.e., below 0.304V or above 0.336V) warrants investigation of the corresponding voltage divider resistors.
• Replacement resistors must be exact values — do not substitute approximate values. Use 0402-package resistors with 1% or better tolerance.

EEPROM Management

On noPIC boards, the AT24C02 (or compatible) I2C EEPROM replaces many of the PIC’s functions for board identification and basic configuration storage. This tiny chip — typically an 8-pin package — stores:

• Board serial number — used by the control board to identify which hashboard is connected to which chain.
• Board revision data — tells the firmware which noPIC board layout to expect.
• Basic configuration parameters — default frequency, voltage table index, and other initialization data the firmware needs during boot.

EEPROM failure modes on noPIC boards:

• Corrupt data: The EEPROM is readable but contains invalid values. The firmware may initialize the board with wrong parameters, causing unstable operation, low hashrate, or immediate shutdown. Reprogramming with known-good data resolves this.
• Unreadable EEPROM: The I2C bus cannot communicate with the EEPROM. Causes include cold solder joints on the EEPROM chip, a damaged I2C bus pull-up resistor, or a physically damaged EEPROM IC. This produces “EEPROM Error” in the log and the hashboard will not initialize.
• Blank EEPROM: An EEPROM that has been replaced but not programmed will contain 0xFF in all addresses. The firmware cannot use this data and will refuse to initialize the board.

Common Repairs

This section covers the repairs you will encounter most frequently on the noPIC S19j Pro. The procedures are organized from simplest to most complex. Start at the top and work down — the simpler fix is more likely to be the correct one.

Firmware Compatibility Issues

The single most common “failure” on a noPIC S19j Pro is not a hardware failure at all — it is running the wrong firmware. Standard Bitmain firmware designed for PIC boards will not properly initialize noPIC hashboards. The symptoms look exactly like a hardware failure: zero chips detected, hashboards not initializing, or chains missing from the dashboard.

Diagnosis:

1. SSH into the miner and check the firmware version: cat /etc/bitmain-release
2. Look for “noPIC” or “NP” in the firmware version string.
3. Check the kernel log for PIC-related error messages: dmesg | grep -i "pic"
4. If you see messages like “PIC not found,” “PIC communication failed,” or “PIC timeout” — and these are treated as errors (not informational) — you are running PIC firmware on a noPIC board.

Resolution:

1. Obtain the correct noPIC firmware for the S19j Pro from Bitmain’s download center or a verified community source.
2. Flash the firmware via the web dashboard (System > Upgrade > Flash Firmware) or via SSH using the runUpgrade.sh script.
3. After flashing, the miner will reboot. Allow 3–5 minutes for all four noPIC hashboards to initialize.
4. Verify all 4 chains show 126 chips each.

EEPROM Repair & Reprogramming

This is the noPIC equivalent of “PIC reprogramming” on standard boards — and it is one of the most common board-level repairs specific to noPIC hardware.

When EEPROM repair is needed:

• The kernel log shows “EEPROM read error” or “I2C communication failure” on a specific chain.
• A hashboard that was working suddenly stops initializing with no physical changes to the setup.
• After a power surge or unclean shutdown, one hashboard fails to start.

EEPROM reprogramming procedure:

1. Back up first — if the EEPROM is still readable, back up its current contents before making changes.
2. Verify I2C bus integrity — check the pull-up resistors on the I2C SDA and SCL lines. These are typically 4.7KΩ resistors pulling to 3.3V. An open or damaged pull-up resistor prevents I2C communication entirely.
3. Check solder joints — inspect the EEPROM chip (AT24C02) solder joints under magnification. Cold joints or cracked solder are common, especially if the board has been subjected to thermal cycling or vibration.
4. Re-flow or replace the EEPROM — if solder joints look suspect, re-flow them first. If the chip is physically damaged, replace the AT24C02.
5. Program the EEPROM — using an I2C programmer, write the correct noPIC S19j Pro EEPROM data to the chip. Use your backup from step 1 if available. If not, you will need a known-good EEPROM image for this specific board revision.
6. Test the hashboard — reinstall and verify all 126 chips are detected.

Voltage Divider Resistor Repair

This repair is unique to noPIC boards and does not exist on PIC variants. When a voltage domain shows incorrect voltage and the buck converter itself tests good, the problem is almost always in the resistor divider network.

Diagnosis:

1. Measure each voltage domain with a multimeter. Expected: ~0.32V per domain.
2. Identify any domain that is significantly off — above 0.336V or below 0.304V.
3. Locate the voltage divider resistors for that domain on the PCB.
4. Measure each resistor individually (desolder one end to get an accurate reading if necessary).
5. Compare measured values against the expected values from the board schematic.

Repair:

1. Replace any resistors that have drifted more than 2% from their nominal value.
2. Use exact-value replacement resistors in 0402 package with 1% or better tolerance.
3. After replacement, verify the domain voltage before installing the board. Connect to a test fixture or PSU and measure the domain output — it should read within ±2% of 0.32V.
4. If the voltage is still off after resistor replacement, the buck converter IC for that domain may be damaged and requires replacement.

Hashboard Chip Repair

Chip-level repairs on noPIC boards follow the same fundamental procedures as PIC boards — the BM1362 chips are identical, and the chip-to-chip signal chain operates identically. The difference is in how you arrive at the diagnosis (no PIC circuit to check) and how you verify the repair (EEPROM rather than PIC validation).

Scenario 1: Zero Chips Detected (ASICNG with 0 chips)

When a noPIC hashboard reports zero chips, the diagnostic path is different from the PIC version:

1. Verify firmware compatibility — this is step zero on noPIC. Confirm you are running noPIC-compatible firmware. PIC firmware will always show 0 chips on a noPIC board.
2. Check the EEPROM — verify I2C communication with the AT24C02. If the EEPROM is unreadable, the firmware cannot identify the board type and will not attempt initialization. Check I2C pull-up resistors (4.7KΩ to 3.3V on SDA and SCL).
3. Check the power supply output — verify the PSU is delivering correct voltage to the hashboard. Look for short circuits in the MOS transistors by measuring resistance between pins 1, 4, and 8.
4. Check voltage domain outputs — each domain should show approximately 0.32V. On noPIC boards, if the voltage divider resistors are intact and the buck converter has 15V input, you should see domain voltage. If not, the buck converter or its drive circuit has failed.
5. Check the boost circuit — measure voltage across C915. Should be approximately 20V. If significantly lower or zero, the boost circuit (U238) has failed.
6. Check LDO 1.2V and PLL 0.8V outputs — probe each LDO and PLL output pin with a multimeter (negative lead on GND). LDO should read ~1.2V, PLL should read ~0.8V. Deviations indicate failed regulators or short-circuited filter capacitors.
7. Check chip signals — measure CLK, CI, RI, BO, and RST at the test points between chips.

Scenario 2: Incomplete Chip Detection (ASICNG with X chips)

When the hashboard detects some but not all 126 chips, the troubleshooting is the same as on PIC boards — the signal chain between chips is identical regardless of PIC presence:

• ASICNG (X): Check the CLK, CI, and BO resistors on the front and back of the Xth chip. Check for cold solder joints on the chip itself.
• Partial detection at high baud rate: Use the binary search method (dichotomy) to isolate the faulty chip:
  1. Short-circuit the RO test point and 1V2 test point between chip 63 and chip 64 (midpoint).
  2. Run the detection software. If 63 chips are found, the first half is good.
  3. Continue halving until the specific faulty chip is identified.
  4. Inspect the chip visually. If appearance is normal, replace it — BM1362 chips can be internally damaged with no visible external signs.

Scenario 3: Pattern NG (Nonce Response Data Incomplete)

When the PT2 station reports Pattern NG, one or more chips are returning corrupted or incomplete nonce data. The chip is detected but not functioning correctly:

• Examine the test log for chips with significantly lower response rates compared to others in the same domain.
• On noPIC boards, also verify the voltage divider for that domain is delivering exactly the right voltage. Even a slight voltage deviation that would be corrected by PIC trim on a standard board can cause Pattern NG on a noPIC board.
• If voltage is correct, the chip itself is likely degraded. Replace the BM1362 chip with the lowest response rate in the affected domain group.

BM1362 Chip Replacement Procedure

The BM1362 replacement procedure on noPIC boards is identical to the PIC version at the chip level:

1. Pre-tin the replacement chip — apply solder paste (138°C) to the new BM1362 chip pins before placement.
2. Remove the faulty chip — use the hot air rework station to heat the chip evenly until solder melts. Lift straight up. On noPIC boards, shield the adjacent voltage divider resistors with Kapton tape or aluminum foil to prevent heat damage.
3. Clean the pads — use desoldering wick and flux to clean the PCB pads. Inspect under magnification for lifted or damaged pads.
4. Place and solder the new chip — align the pre-tinned chip on the cleaned pads. Apply heat evenly with the rework station.
5. Post-soldering inspection — verify no adjacent components were displaced. On noPIC boards, specifically check that the voltage divider resistors near the repair site are still properly soldered and in position.
6. Apply thermal gel — apply thermally conductive gel evenly on the chip surface, then lock the heatsink in place.
7. Cool and test — let the repaired hashboard cool completely before testing.
8. Test twice — the repaired hashboard must pass the test fixture at least two times with a cooling period between tests.

Power Supply Issues

The APW12 power supply unit is shared between PIC and noPIC variants — PSU diagnostics are identical. However, noPIC boards are less tolerant of marginal PSU performance because they lack the dynamic voltage compensation that PIC-stored trim values provide on standard boards.

PSU diagnostic checks:

• Input voltage: Verify your wall supply is delivering 200–240V AC. Below 200V, the APW12 may not deliver stable output. North American 120V circuits are insufficient — you need a 240V circuit (typically a dryer or EV charger outlet, or a dedicated 240V run).
• Output voltage under load: The APW12 should deliver approximately 15V DC under load to the hashboards. Measure at the PSU output connector while the miner is running. If the voltage sags below 14.5V under full load, the PSU is degraded.
• Voltage ripple: Use an oscilloscope to check for excessive ripple on the 15V DC output. More than 200mV peak-to-peak ripple at full load indicates failing output capacitors in the PSU.
• PSU fan: If the APW12’s internal fan fails, the PSU will thermally throttle or shut down. Listen for the PSU fan and verify it is spinning.

On noPIC boards specifically: PSU voltage sag that would be partially compensated by PIC voltage trim on a standard board hits noPIC boards harder. If you experience intermittent hashrate drops, high hardware errors, or random board disconnections during peak load, suspect PSU degradation before investigating the hashboards themselves.

Network & Control Board Issues

The control board is the brain of the S19j Pro — it communicates with all four hashboards, manages fan speeds, connects to the pool, and runs the firmware. On noPIC miners, the control board firmware plays a more active role in voltage initialization (writing default parameters directly rather than reading PIC data), so firmware integrity and control board health are even more critical.

Common control board problems:

• IP not detected on network: Check the Ethernet cable (try a different cable). Verify the IP scanner is scanning the correct subnet. Try a direct connection to your router. If the control board LED shows no network activity, the Ethernet port or control board may be faulty.
• Missing chain (fewer than 4 hashboards): First check the physical ribbon cable connection between the hashboard and control board port. If solid, swap the ribbon cable with a known-good one. On noPIC boards, also verify the EEPROM on the missing board is readable — the control board needs to read the EEPROM to identify and initialize each hashboard. If the EEPROM is corrupt, only that specific board will fail to initialize.
• Random reboots or freezes: Often caused by corrupted firmware, marginal power delivery, or overheating. On noPIC miners, ensure you are running noPIC-compatible firmware — incompatible firmware can cause boot loops as the firmware repeatedly fails to find PIC chips and restarts.
• Fan display abnormal: Verify fans are physically spinning and properly connected. Check control board fan headers for bent or broken pins.

Temperature Sensor Troubleshooting

The S19j Pro uses temperature sensors on each hashboard to monitor chip temperatures. On noPIC boards, the temperature sensor circuit is simplified — the sensors feed data through a direct path rather than being mediated by the PIC chip. This means fewer points of failure in the temperature sensing system, but it also means the firmware receives less-processed temperature data.

noPIC temperature sensor diagnostics:

1. Check sensor circuit power supply — verify 3.3V is present at the temperature sensor power pins. On noPIC boards, this 3.3V line is typically supplied directly from the board’s LDO regulator, not through the PIC.
2. Inspect sensor ICs — check each temperature sensor for physical damage and cold solder joints. The sensors are small packages located on the back of the PCB.
3. Check supporting resistors — each temperature sensor has associated pull-up/pull-down resistors for signal conditioning. Verify these are intact and properly soldered.
4. Verify I2C/signal bus — temperature data travels to the control board via the hashboard ribbon cable. If only one board shows temperature anomalies, the sensor circuit on that board is the likely culprit. If all boards show anomalies, suspect the control board or firmware.
5. Heatsink contact — poor heatsink-to-chip contact causes real temperature differentials that sensors correctly report as abnormal. Inspect heatsink flatness and thermal gel application.

Firmware & Software

noPIC Firmware Compatibility

This is the most critical software consideration for noPIC miners. Running the wrong firmware is the number one cause of “dead” noPIC boards that are perfectly functional hardware.

Firmware Updates

Updating firmware on a noPIC S19j Pro requires extra care because flashing the wrong firmware build (PIC instead of noPIC) will render all hashboards undetectable:

• Verify the firmware is noPIC-compatible before downloading. Check the filename, release notes, and any documentation for “noPIC” or “NP” designation.
• Back up your current configuration — pool settings, network configuration, tuning profiles.
• Back up EEPROM data — as an extra precaution, if you have the tools to read EEPROM data, do so before any firmware change.
• Never interrupt a firmware update — if the green LED is fast-blinking, the miner is writing firmware. Power loss during this process can brick the control board.
• Test after updating — verify all four hashboards are detected, chip counts are at 126 each, and hashrate returns to normal within 5 minutes.
• Keep a recovery firmware image — have a known-good noPIC firmware image on a USB drive or SD card in case a firmware update goes wrong and you need to recover via the control board’s emergency flash mode.

Alternative Firmware for noPIC

Third-party firmware options can unlock significant performance and efficiency improvements on noPIC S19j Pro miners:

• BraiinsOS+ — The top recommendation for noPIC miners. BraiinsOS+ auto-detects whether hashboards are PIC or noPIC and adjusts initialization accordingly. Its autotuning feature optimizes each chip individually, which is especially valuable on noPIC boards where the fixed voltage dividers cannot be dynamically adjusted. Autotuning compensates at the firmware level for what noPIC lacks at the hardware level. Supports underclocking for home mining use.
• LuxOS — Supports noPIC boards with advanced tuning and fleet management. Verify your version explicitly supports the S19j Pro noPIC before flashing.

Configuration Best Practices

• Change default credentials immediately — the default root / root is an open invitation. Set a strong, unique password.
• Configure multiple pool addresses — set Pool 1, Pool 2, and Pool 3 for failover. Prevents hashrate downtime if your primary pool goes down.
• Set appropriate fan speed profiles — for home mining, running at a fixed 60–70% fan speed with underclocked hashrate balances noise and cooling. On noPIC boards, consistent cooling is especially important for voltage divider stability.
• Enable monitoring alerts — configure email or webhook alerts for hashrate drops, temperature warnings, or hashboard disconnections. On noPIC boards, an “EEPROM error” alert is an early warning of a problem that will become a full board failure if not addressed.
• Document your settings — screenshot or export your pool configuration, network settings, and tuning profiles. Include your firmware version and build type (noPIC) in the documentation.
• Record baseline voltages — after initial setup with a working noPIC configuration, SSH in and record the voltage domain readings for all four hashboards. Save this as your baseline. Future voltage measurements can be compared against this baseline to detect resistor drift before it causes failures.

Whole-Miner Troubleshooting

Some problems manifest at the whole-miner level rather than on an individual hashboard. On noPIC miners, certain whole-miner failures have additional or different root causes compared to PIC variants.

Maintenance & Repair Flowchart — noPIC Edition

When a noPIC hashboard fails, follow this systematic approach. The key difference from the PIC flowchart is the addition of EEPROM and firmware checks at the beginning, and the replacement of PIC-specific diagnostics with voltage divider checks:

1. Firmware Check (noPIC-Specific Step)
   • Confirm the miner is running noPIC-compatible firmware.
   • If firmware is wrong, flash the correct noPIC build and retest before any hardware diagnostics.
2. EEPROM Check (noPIC-Specific Step)
   • Check kernel log for EEPROM errors on the failing chain.
   • If EEPROM errors are present, investigate I2C bus integrity and EEPROM chip condition.
   • Reprogram EEPROM if necessary.
3. Routine Inspection
   • Visually inspect the board for PCB deformation, scorching, burnt marks, collision offset parts, or missing components.
   • Test the impedance of each voltage domain to detect short circuits or open circuits.
   • Each domain voltage should be approximately 0.32V.
   • On noPIC boards: also inspect the voltage divider resistor area for any discoloration or component damage.
4. Chip Test (PT1)
   • Use the hashboard test fixture configured for noPIC operation.
   • The test fixture should detect the board type via EEPROM and skip PIC validation.
5. Locate the Faulty Chip
   • Based on the test result, check the test points (CO, NRST, RO, XIN, BI) and voltages (VDD0V8, VDD1V2) near the reported fault position.
   • Signal flow direction is the same as PIC boards: CLK, CO, BO, and RST are forward signals. RX is backward.
6. Repair
   • Try re-soldering first: add flux around the chip, heat to dissolve state, allow solder to re-flow.
   • If re-soldering does not fix the issue, replace the BM1362 chip.
   • On noPIC boards: protect adjacent voltage divider resistors from heat during rework.
7. Verify
   • After repair, let the board cool completely.
   • Test at least twice on the test fixture (noPIC mode). Both tests must pass.
   • After chip replacement, also verify the voltage domains near the repair site have not shifted due to heat damage to nearby resistors.

Frequently Asked Questions

When to Call a Professional

This guide covers a lot of ground, but there is a clear line between what you should attempt and what requires professional intervention. On noPIC boards, some tasks are actually easier for the DIY miner (no PIC programming needed), while others are more nuanced (voltage divider precision work).

DIY-appropriate tasks:

• All routine maintenance (cleaning, visual inspection, thermal gel replacement)
• Fan replacement
• Ribbon cable troubleshooting and replacement
• Firmware updates (verifying noPIC compatibility before flashing)
• PSU swaps
• Control board replacement
• Basic diagnostics via dashboard and SSH
• Firmware troubleshooting (wrong firmware is the #1 noPIC issue and requires zero hardware skill)

Professional repair required:

• BM1362 chip replacement (BGA rework)
• EEPROM reprogramming (requires I2C programmer and known-good data)
• Voltage divider resistor replacement (requires exact-value components and precision soldering)
• Boost circuit repair
• Damaged PCB traces
• Multiple chip failures on a single board
• Buck converter IC replacement
• Any repair requiring an oscilloscope for signal tracing
• Board-type conversion (PIC to noPIC or vice versa)

The noPIC S19j Pro’s 126 chips per board and precision voltage divider networks make professional repair especially valuable. A board-level technician with the right equipment and the correct schematic for your board revision can diagnose and fix a specific failure in an hour. An amateur attempting voltage divider repair without the correct resistor values can turn a $50 fix into a destroyed $300+ hashboard. Know your limits — and know that asking for help is not weakness. It is smart economics.

Interactive Hashboard Schematic

Explore the ANTMINER S19J PRO NOPIC hashboard layout below. Toggle layers to isolate voltage domains, signal chains, test points, key components, and thermal zones. Hover over any region for quick specs — click for detailed diagnostics, failure modes, and repair guidance.