Power Supply Issues — Troubleshooting Guide

Diagnose and fix power supply failures, no-power conditions, and PSU-related problems on Antminer, Whatsminer, and Avalon ASIC miners. Covers APW, P21, P22, and generic PSU testing.

Symptoms

You are experiencing one or more of the following:

Miner shows no signs of life -- no LEDs, no fan spin, completely dead
PSU clicks, buzzes, or makes a popping sound when power is applied
Fans spin briefly then everything shuts off (PSU trips under load)
Partial power -- some boards work but others fail to start
PSU is abnormally hot or produces a burning smell
Miner powers on but hash boards fail to initialize (insufficient voltage)
Voltage readings on PSU outputs are out of specification
PSU shuts down intermittently under load

Danger -- High Voltage: Power supplies contain lethal voltages internally even when unplugged. Never open a PSU enclosure unless you are a qualified electronics technician. The input side carries mains voltage (120V/240V AC). The output side, while lower voltage, can deliver hundreds of amps -- enough to cause severe burns or weld metal tools to contacts. Always disconnect from mains power and wait at least 5 minutes before handling PSU connections.

PSU Models by Manufacturer

Bitmain APW Series

PSU Model	Output Voltage	Max Power	Used With
APW7	12V DC	1,800W (120V) / 2,800W (240V)	S9, L3+
APW9	12V DC	3,600W (240V)	S17, T17
APW9+	12V DC	3,600W (240V)	S17 Pro
APW12	12V DC	3,600W (240V)	S19, S19 Pro, T19
APW121215	12V DC	5,400W (240V)	S19 XP, S19k Pro
APW15	48V DC	5,400W (240V)	S21, S21 Pro, T21

MicroBT Whatsminer

PSU Model	Output Voltage	Max Power	Used With
P21	12V DC	3,600W (240V)	M30S, M30S++
P21D	12V DC	3,600W (240V)	M30S (integrated)
P22	12V DC	3,600W (240V)	M50, M50S
P23	12V DC	5,400W (240V)	M56S, M60, M60S

Canaan Avalon

Avalon miners typically use the Avalon PSU (model varies by generation) or can be powered by compatible third-party PSUs. Newer Avalon models (A1366, A1466) come with integrated or matching PSUs rated at 3,000-3,600W.

Most high-power mining PSUs require 240V input to deliver their full rated power. Running on 120V significantly reduces available wattage (typically to about half) and may cause the PSU to trip under full load. If your miner requires more than 1,800W, you almost certainly need a 240V circuit.

Quick Checks

Is the wall outlet working? Plug in a known-working device (lamp, phone charger) to confirm the outlet has power.
Is the power cord securely connected? Check both ends -- the wall plug and the PSU inlet (C13/C14 or C19/C20 connector). Wiggle the connectors to check for looseness.
Is the PSU power switch on? Some PSUs have a physical ON/OFF switch on the back. It must be in the ON (I) position.
Is the correct voltage selected? Some older PSUs (APW7) have a 120V/240V selector switch. The wrong setting can damage the PSU or prevent it from starting.
Are the PSU-to-miner power cables fully seated? Check each power connector between the PSU and the hash boards. These are high-current connections and must be tight.
Is the circuit breaker tripped? Check your electrical panel. Mining PSUs draw significant current (15-25A at 240V). A tripped breaker means the circuit is overloaded or has a fault.

Diagnostic Flowchart

Miner won't power on / PSU problems
│
├─ No signs of life (no LED, no fan)
│  ├─ Wall outlet working? (test with another device)
│  │  ├─ NO → Tripped breaker, blown fuse, or dead outlet
│  │  └─ YES → Continue
│  │
│  ├─ Power cord good? (try a known-good cord)
│  │  ├─ NO → Replace power cord
│  │  └─ YES → Continue
│  │
│  ├─ PSU switch ON?
│  │  ├─ NO → Turn it on
│  │  └─ YES → PSU may be dead
│  │     ├─ Test PSU independently (see below)
│  │     ├─ PSU outputs correct voltage → Control board short
│  │     └─ PSU outputs 0V or wrong voltage → PSU failed
│  │
├─ PSU clicks/buzzes then shuts off
│  ├─ Disconnected from miner, does PSU turn on alone?
│  │  ├─ YES → Hash board or control board has a short
│  │  │  └─ Connect one board at a time to find the shorted board
│  │  └─ NO → PSU internal failure (capacitor, MOSFET, or fuse)
│  │
├─ Partial power (some boards work, some don't)
│  ├─ Check voltage at each power connector
│  │  ├─ Voltage present at all → Board-level issue, not PSU
│  │  └─ Voltage missing on some → PSU output rail partially failed
│  │     └─ Or a shorted board is pulling that rail down
│  │
└─ PSU runs but voltage is out of spec
   ├─ Voltage too low (&lt;11.5V for 12V, &lt;46V for 48V)
   │  └─ PSU degraded, overloaded, or input voltage too low
   └─ Voltage too high (>12.8V for 12V, >53V for 48V)
      └─ PSU regulation failure — dangerous, disconnect immediately

Causes

1. Bad Power Cord or Connection

Probability: Very High

The simplest and most common cause. Power cords for miners carry significant current and generate heat at connection points. A loose or damaged connection can prevent power delivery or cause intermittent failures.

Symptoms specific to this cause:

Miner completely dead
Intermittent power losses (miner restarts randomly)
Power cord connector is warm or discolored
Miner works after wiggling the power cord

Diagnosis:

Inspect the Power Cord

Examine the power cord for:

Damaged insulation (cuts, cracks, melted spots)
Bent or corroded prongs on the wall plug
Loose C13/C14 or C19/C20 connector at the PSU end
Discoloration or melting at either connector (indicates overheating from poor contact)

Mining PSUs drawing 15-25A require heavy-duty power cords. A lightweight cord rated for only 10A will overheat and eventually fail.

Test with a Known-Good Cord

Replace the power cord with one that is known to work and is rated for the appropriate current (minimum 15A for most miners, 20A preferred). If the miner powers on with the replacement cord, the original cord was the problem.

Check the Wall Outlet

Use a multimeter to measure voltage at the wall outlet:

120V circuits: Should read 110-125V AC
240V circuits: Should read 220-245V AC

Also check for proper grounding. An ungrounded outlet can cause PSU ground fault protection to trip.

Fix: Replace damaged power cords immediately. Use cords rated for the full current draw of your miner. For 240V installations, use NEMA 6-20 or L6-30 plugs and matching receptacles rated for the load.

Prevention: Use high-quality, properly rated power cords. Do not use extension cords or power strips with miners. Ensure connections are tight and inspect cords periodically for signs of overheating.

2. PSU Internal Failure

Probability: High

Power supplies are complex electronic devices that can fail in many ways. Common failure modes include blown internal fuses, failed MOSFETs, dried-out electrolytic capacitors, and failed control ICs.

Symptoms specific to this cause:

PSU completely dead (no output even when tested independently)
PSU makes a single click then goes silent (internal fuse or protection tripped)
PSU buzzes or whines but produces no output (oscillator running but power stage failed)
PSU outputs voltage briefly then shuts down (over-current or over-temperature protection)
Burning smell from inside the PSU enclosure

Diagnosis:

Isolate the PSU

Disconnect the PSU from the miner completely. Then test whether the PSU can power on by itself:

APW7/APW9/APW12 Standalone Test:

The APW series has a small control connector (6-pin or 10-pin) that connects to the miner's control board. To force the PSU on without the miner:

Locate the control connector on the PSU (small connector, separate from the main power outputs)
Short the ON signal pin to ground (refer to the specific APW model's pinout -- this varies between models)
The PSU should power on and the internal fan should spin
Measure the output voltage at the main power connectors

APW15 (48V): Same principle but the output is 48V DC. Use appropriate voltage range on your multimeter.

The APW pinout varies between models. Shorting the wrong pins can damage the PSU. If you are not sure of the pinout, consult the specific APW model's documentation or use a breakout board designed for PSU testing.

Whatsminer P21/P22/P23 Standalone Test:

Whatsminer PSUs that are separate units (not integrated into the miner chassis) can be tested similarly by shorting the enable signal on the control connector. For integrated PSUs (like the P21D), the PSU and miner share a chassis and cannot be easily separated.

Use the WhatsMiner Tool software to read PSU diagnostics if the miner is at least partially functional. The tool reports input voltage, output voltage, output current, and protection status.

ATX PSU Paperclip Test:

If you are using an ATX-style PSU with adapters:

Disconnect the PSU from everything
Locate the 24-pin ATX connector
Short the green wire (PS_ON, pin 16) to any black wire (ground)
The PSU should power on and the fan should spin
Measure 12V between any yellow wire and any black wire

If the PSU does not turn on or the voltage is incorrect, the PSU has failed.

Measure Output Voltage Under No Load

With the PSU running independently (no miner connected):

12V PSUs: Should read 12.0-12.6V (no load voltage is slightly higher than loaded)
48V PSUs: Should read 48.0-52.0V

If there is no output or the voltage is significantly wrong, the PSU has an internal failure.

Listen and Smell

Clicking sounds on power-up followed by silence = internal fuse blown or protection tripping
Continuous buzzing = power stage partially working but unable to regulate
Burning smell = component has failed catastrophically. Do not continue testing.
Fan spins but no output = secondary-side failure (rectifier or output stage)

Fix: PSU repair requires advanced electronics knowledge and is not recommended for most users due to the lethal voltages inside. Replace the PSU with the correct model for your miner. Ensure the replacement is genuine -- counterfeit PSUs are a known problem in the mining industry.

Prevention: Run PSUs within their rated load (do not overload). Ensure adequate ventilation around the PSU. Use surge protectors or UPS units to protect against voltage spikes. On 120V circuits, be aware that the PSU may be running at or near its capacity limit.

3. Blown Fuse or Tripped Breaker

Probability: Medium-High

Mining operations draw substantial current. A single miner can draw 12-25A at 240V. Circuit breakers and fuses are designed to trip when current exceeds the safe limit. This can happen from overloaded circuits, startup inrush current, or a fault in the miner.

Symptoms specific to this cause:

Miner completely dead, wall outlet also dead
Breaker trips immediately when the miner is turned on
Breaker trips after the miner has been running for a while (thermal trip from sustained overload)
Multiple miners on the same circuit cause intermittent trips

Diagnosis:

Check the Electrical Panel

Locate your breaker panel and check if the breaker for the mining circuit has tripped. A tripped breaker will be in the middle position (not fully ON or OFF). Reset it by pushing it fully OFF then back to ON.

Measure Circuit Load

If the breaker trips repeatedly, measure the total current draw on that circuit using a clamp meter around one of the hot wires. Compare the measured current to the breaker rating:

15A breaker: Should not exceed 12A sustained (80% rule)
20A breaker: Should not exceed 16A sustained
30A breaker: Should not exceed 24A sustained

If the miner's draw exceeds the circuit's safe capacity, you need a dedicated circuit or to redistribute miners across multiple circuits.

Check for Short Circuit

If the breaker trips instantly (rather than after running for a while), there may be a short circuit in the miner, PSU, or wiring. Disconnect the miner and reset the breaker. If it holds, the miner/PSU has an internal short. If it still trips with nothing connected, the building wiring has a fault -- call an electrician.

Fix: For overloaded circuits, redistribute miners or install additional dedicated circuits. For short circuits, isolate the faulty component (see "Hashboard Short" below). For building wiring faults, contact a licensed electrician.

Prevention: Calculate your total power requirements before installing miners. Plan for dedicated 240V circuits rated for the load plus 20% headroom. Never exceed the 80% continuous load rule on any circuit.

4. Control Board Short Circuit

Probability: Medium

A short circuit on the control board can prevent the PSU from starting or cause it to immediately shut down. The PSU's over-current protection detects the excessive current draw and trips.

Symptoms specific to this cause:

PSU clicks once then shuts down when connected to the miner
PSU works fine in standalone test (without the miner)
Connecting only the control board (without hash boards) still causes the PSU to trip
Visible damage or corrosion on the control board

Diagnosis:

Isolate the Control Board

Disconnect all hash boards and fans from the control board. Connect only the control board to the PSU. If the PSU still trips, the control board has a short circuit.

Visual Inspection

Examine the control board for:

Liquid damage residue (white or green corrosion)
Burnt components near the power input area
Solder bridges or debris between pads
Swollen or leaking capacitors

Fix: Control board short circuits typically require board-level repair (finding and replacing the shorted component) or control board replacement. If the control board has liquid damage, clean it thoroughly with isopropyl alcohol before attempting to power it again.

Prevention: Keep miners dry. Use conformal coating on control boards in humid environments. Never hot-swap connections while the miner is powered.

5. Hashboard Short Pulling PSU Down

Probability: Medium

A shorted component on a hash board (failed MOSFET, shorted ASIC chip, or damaged capacitor) can draw excessive current and cause the PSU to shut down via over-current protection.

Symptoms specific to this cause:

PSU works with the miner partially loaded but trips when a specific hash board is connected
Removing one specific hash board allows the remaining boards to work
The suspect hash board may have a visible short (burn mark, damaged component)
PSU worked fine before; problem started suddenly

Diagnosis:

Progressive Load Test

Start with the PSU connected to only the control board (no hash boards). Power on and verify stability. Then connect hash boards one at a time, powering the miner on between each addition:

Control board only -- PSU stable? Continue.
Add hash board 1 -- PSU stable? Continue.
Add hash board 2 -- PSU stable? Continue.
Add hash board 3 -- PSU trips? Board 3 has the short.

Resistance Measurement

With the miner completely unpowered, measure the resistance across the power input pins of the suspect hash board:

Normal board: Should show moderate resistance (varies by model, typically 1-10 ohms)
Shorted board: Will show very low resistance (less than 0.5 ohms) or near zero

Compare the reading with the working boards for reference.

Fix: The shorted hash board needs component-level repair to find and replace the shorted component. Common culprits are MOSFETs in the voltage regulator circuits and shorted ASIC chips. See the Antminer S21 Hashboard Repair Guide for repair procedures.

Prevention: Use surge protection. Maintain proper cooling to prevent thermal damage to components. Avoid running boards above specified voltage limits.

6. Input Voltage Too Low

Probability: Medium-Low

Mining PSUs are sensitive to input voltage. If the incoming AC voltage is too low (brownout condition or undersized wiring), the PSU may fail to start or may shut down under load.

Symptoms specific to this cause:

Miner works at low hashrate but trips under full load
Problems are worse during peak electricity demand times (afternoons, summer)
Multiple miners on the same circuit cause voltage drop
PSU works fine on a different circuit

Diagnosis:

Measure the AC voltage at the wall outlet with the miner running (under load). Voltage should be:

120V circuits: 110-125V AC
240V circuits: 210-245V AC

If voltage drops below these ranges under load, the circuit wiring is undersized or the utility supply is low. Long wire runs from the panel to the outlet cause resistive voltage drop, which gets worse with higher current.

Fix: For wiring issues, have an electrician upgrade the circuit wiring gauge or add a dedicated circuit with appropriately sized wire. For utility voltage issues, consider a voltage stabilizer or step-up transformer. Moving miners closer to the electrical panel can also help.

Prevention: Use properly sized wiring for the expected current draw. Keep wire runs as short as practical. Install voltage monitoring to detect sag conditions early.

How to Test a PSU with a Multimeter

Set Up Your Multimeter

Set the multimeter to DC Voltage mode, with a range of at least 20V (for 12V PSUs) or 100V (for 48V PSUs). Use the red probe in the V/ohm port and the black probe in the COM port.

Measure Output Voltage

Place the red probe on a positive (+) output terminal or pin of the PSU's power connector, and the black probe on a negative (-) or ground terminal. Read the voltage:

12V PSU (APW7/9/12, P21/22): Expected 11.8-12.6V
48V PSU (APW15, P23): Expected 47.0-52.0V

Measure at multiple connectors to verify all outputs are consistent.

Check Under Load

If the PSU reads normal voltage with no load but you suspect it fails under load, you need a load tester or the actual miner connected. Measure voltage at the PSU output while the miner is running. Significant voltage sag under load (more than 5% drop from no-load) indicates a failing PSU.

Measure Input Voltage

Switch the multimeter to AC Voltage mode (at least 300V range). Carefully measure the voltage at the PSU's input cord plug. This tells you if your building supply is adequate.

Measuring AC mains voltage is dangerous. If you are not comfortable working with live mains voltage, have a qualified electrician perform this measurement.

When to Seek Professional Help

Contact a qualified repair technician or electrician if:

You suspect a short circuit in the miner but cannot isolate which board is causing it
The PSU produces a burning smell or visible smoke -- do not use it again
Circuit breakers trip repeatedly even after reducing load -- this may indicate a building wiring fault
You need to install or modify 240V electrical circuits (always use a licensed electrician)
The PSU outputs voltage but the miner still does not power on (possible control board issue)

Frequently Asked Questions

Q: Can I use a different brand's PSU with my miner?

Generally no. Mining PSUs have specific connector pinouts, voltage requirements, and control signals that vary by manufacturer. Using an incompatible PSU can damage the miner or the PSU. Some third-party PSU manufacturers make compatible replacements -- verify the specifications carefully.

Q: My PSU fan runs but there is no output voltage. Is it dead?

The PSU fan running indicates the standby power supply (low-voltage internal circuit) is working, but the main power stage has failed. The PSU needs repair or replacement. In some cases, a failed control signal from the miner prevents the PSU from enabling its main output -- try the standalone test first.

Q: Can I run two PSUs on one miner?

Some large miners are designed for dual PSU configurations (like the S19 XP with dual APW121215). Only use dual PSU configurations that the manufacturer explicitly supports. Connecting two PSUs that are not designed for parallel operation can cause current imbalance, damage, or fire.

Q: My PSU buzzes loudly. Is that normal?

Some electrical buzz is normal under heavy load (coil whine from inductors). Loud buzzing, clicking, or popping sounds are abnormal and indicate potential component failure. Monitor the situation closely and replace the PSU if the noise worsens or is accompanied by voltage instability.

Q: How long do mining PSUs typically last?

Mining PSUs operated within their ratings typically last 3-5 years. Factors that reduce lifespan include: operating at maximum rated load continuously, poor ventilation (PSU overheating), low input voltage (causes the PSU to work harder), and power surges. The electrolytic capacitors inside the PSU are the most common wear-out component.

Q: I heard a loud pop from my PSU and now it is dead. What happened?

A loud pop typically indicates a failed MOSFET, blown fuse, or shorted capacitor inside the PSU. Do not attempt to power it on again. The PSU needs professional repair or replacement. Check for a burning smell -- if present, a component has catastrophically failed.

Miner Shows No Hashrate -- PSU failure is a common cause of no hashrate
Fan Errors -- PSU must provide 12V to fans
Over-Temperature -- PSU overheating
Firmware Corruption -- Power loss during firmware update
How Hash Boards Work -- Understanding power delivery to hash boards

Power Supply Issues — Troubleshooting Guide

On this page