Applies to: Thunder Laser machines equipped with an Air Assist system (Nova, Nova Plus, Odin, Bolt, Bolt Plus, and Titan series).

If little or no air is coming out of your nozzle, this guide will help you find out why. Your air assist is a chain of parts — a power/signal side and an air-path side — and a problem anywhere along that chain can stop the air. The good news is that the machine gives you several built-in ways to see exactly where the chain breaks. Read the overview first so you know what the parts are, then follow the steps in order.

Overview- How Your Air Assist Works

There are two systems working together: the electrical path that tells the air to turn on and which stage (High or Low), and the physical air path that the air travels through from the pump to the Laser Head. Any of the parts below can be a point of failure, so it helps to picture the whole chain.

The Electrical / Control Signal path

1. DSP controller — while a job runs, the controller sends two signals to the TL Timer: one that says run air assist now, and one that says high or low.
2. TL Timer — receives signals from the DSP controller and switches its discrete outputs on or off accordingly. It is the brain that activates which air stage fires and when.
3. Green test buttons (high and low) — these buttons wire back to the TL Timer. When a stage's output is active, that button lights up. Because the button light comes from the same output that triggers the relay, the green light is a built-in feedback signal — it tells you the TL Timer is commanding that stage.
4. Relays — on a dual-air machine there is a separate relay for high air and low air. The TL Timer triggers the relay through its output. Each relay has a green light indicator that is on when the relay is triggered.
5. What the relay powers — when a relay switches on, it does two jobs at once:
   • It sends power to the air pump (120V on all machines except the Titan, which is 220V). The pump itself is powered by the machine — through an external socket, or an internal quick-connect plug on the smaller desktop units.
   • It sends 24VDC to the solenoid (the valve that lets air pass). The 24V connection runs through a JST SM 2-pin connector between the relay and the solenoid.

The physical Air Flow path

1. Air pump → a fitting and hose connect to the back of the machine through a 6mm push-to-connect bulkhead connector if the pump is external. Internal pumps plumb directly to the Y for the solenoids.
2. On the inside of the machine, the air hose is run from the bulkhead to the Y to feed the solenoid(s) — one branch per stage on a dual-air machine.
3. Each solenoid has an exit hose that feeds a needle valve (Your flow-rate adjustment for that stage).
4. After the needle valves, the high and low air lines Y back together (on dual air).
5. The combined line routes over to the laser head through the drag chains, and connects at the head through a quick-connect or compression fitting → out the nozzle.

So when you press an Air Assist test button…

The TL Timer fires that stage's output → the green button lights → the relay switches on → the pump gets power (you should hear it) and the solenoid gets 24V (it opens) → air flows through the needle valve, up the drag chain, and out the nozzle. Knowing this sequence is what lets you pinpoint a failure: you follow it until you reach the point where it stops.

The Tools You'll Use

You'll diagnose this with a combination of these:

• Your eyes (connections and lights): check that hoses and electrical connectors are seated and intact along the whole chain. The TL Timer, the relay, and the green test button all have indicator lights. Watching which ones come on tells you how far the signal is getting.
• Your ears: you should hear the air pump run when a stage is triggered.
• A multimeter: to confirm power is actually present at a connection (pump power, or 24V at the solenoid).
• A manual trigger: the green test buttons, or the air-assist test on the GT5 touchscreen on applicable models, let you fire the air pump on demand without running a job.

Safety first. The pump power side is line voltage — 120V (or 220V on the Titan). Always power the machine off before opening any panel or touching wiring, and only take live electrical measurements if you are trained and comfortable doing so. The 24V solenoid side is low voltage, but the same "power off before unplugging connectors" rule applies. If you are not comfortable working inside the machine, stop and contact support — we will guide you.

Reference Images

Air Pump

External type pumps are commonly found on Mini 60, Nova, Odin and larger Bolt Machines. Internal pumps are common on Desktop Bolt and the Titan series.

External	Internal

Air Pump Electrical Connector

External pumps plug into a socket on the back of the machine. Internal air pumps have an electrical connector.

External	Internal

Relay LED Light

When an air stage is activated, its corresponding relay will light up Green as shown. Dual air machines have 2 relays to control the Air Pump and each solenoid. Single air machines will only have 1 relay and no solenoid.

On	Off

Low air stage on a Nova Plus show above. Depending on your machine, the relays may be stacked vertically and have a different layout. You can gauge which relay is which based of the wires terminated on the relay and the information in your machines TL Timer Schematics. 

TL Timer LED light

V8.x (Commonly found on Nova, Odin and Nova Plus). Shown below is the low air stage on a V8.4 TL Timer on a Nova plus.

Off	On

V9.x (Commonly found on Bolt and Titan Series)

Off	On

Solenoids and Connectors

Exact model solenoid and configuration can vary by model. Examples are shown here:

Nova Plus Example	Titan example

Bolt Single (No Solenoid, empty space)	Bolt Dual Air (In front of TL Timer)

Air Flow Needle Valves

Valve type and quantity can vary by model. The metal knob type have a visual reference for how open or closed the valve is that the plastic cap type do not.

Metal	Plastic Cap

Bolt with Single Air (And older machines and Mini 60):

You will have a single air valve on the back of the Gantry, metal knob type typically:

Bulkhead Connector

If you have an external air pump type machine, the bulkhead will be used in the OEM configuration. If you have an internal air pump type machine, then the bulkhead is installed for the option of adding and External air compressor and remains unused otherwise.

External Pump	Internal Pump

Air Test Buttons: AKA Green Buttons

Each stage (low and high) will have its own button. On a single air machine like a bolt, you will not have a green test button. In the example below, the Low air stage is shown on a Titan control panel.

Off	On

GT5 Touchscreen Test Button

If you have a machine with the touchscreen, you can activate the Air Assist and Both stages simultaneously. Both the high and low air relays will activate. Not the best troubleshooting method if working on just a single stage of air having issues. (Tl timer can individually activate each air stage)

Off (Intelligent mode)	On (Standard Mode)

For more on using the TL timer to activate the individual stages, see here.

Hose Conversion Fitting

If your X axis gantry has the softer hose, there is likely a push-to-connect to compression type fitting that converts from the hard type hose to the soft type hose:

 

Step 1: Fire a Stage and Watch the Green Light

Press the low test button, then the high test button (or trigger each from the GT5 screen). For each one, note three things:

1. Does the green button light up?
2. Do you hear the pump run?
3. Does air come out of the nozzle?

These three answers split the problem cleanly between the electrical side and the air side:

Step 2: Electrical Side (no light, or no pump)

Follow the lights from the controller outward. Power the machine off before touching any wiring or connector.

If the green button doesn't light when you press it:

• The signal isn't leaving the TL Timer for that stage. Check the TL Timer's own indicator light for that channel and the wiring from the button to the TL Timer.
• If the TL Timer light won't come on for that channel either, the TL Timer (or its trigger) is the suspect — contact support.

If the green button lights but you don't hear the pump:

• The TL Timer is doing its job, but the relay isn't delivering power. Check the relay's indicator light:
  • Relay light off → the relay isn't being triggered (wiring between the TL Timer output and relay, or the relay coil).
  • Relay light on, but pump still silent → the relay is switched but power isn't reaching the pump. With the machine safely powered for testing, a meter can confirm whether voltage is present at the pump's power connection (remember: 120V, or 220V on a Titan). No voltage points to the relay contacts or pump power wiring; voltage present but a dead pump points to the pump itself.

In most "light is on but nothing happens" cases on the electrical side, the fix involves a loose terminal at the relay or wiring and is worth a quick check-in with support — tell us which lights you saw and we'll point you to the right part.

Step 3: Air Side (lights and pump are fine, but no air)

If the green light is on and you can hear the pump running but no air reaches the nozzle, power is good and the problem is somewhere in the air path or the solenoid. Work from the solenoid outward.

1. Is the solenoid getting its 24V? The solenoid opens only when it receives 24VDC through the JST SM 2-pin connector from the relay. Confirm that connector is fully seated. With the machine safely powered for a test, a meter can verify 24V is present at the connector.
   • 24V present but no air passes → the solenoid has likely failed internally (mechanical failure inside the valve). It won't open even though it's being told to.
   • No 24V at the connector → the issue is back on the electrical side (relay or the JST connection) — see Step 2.
2. Is the needle valve open — and working? Open the flow-control (needle) valve for that stage and re-test. If it's open and still no air passes, the needle valve can fail internally and block flow.
3. Check the hoses for holes or splits. Air hoses can develop holes from popping off under pressure or from melting (heat near the head). A hole anywhere along the run bleeds off the air before it reaches the nozzle. Inspect the full path:
   • The 6mm push-to-connect bulkhead at the back of the machine — re-seat it.
   • The Y fittings that split to the solenoids and recombine after the needle valves.
   • The hose run through the drag chains (a common spot for melting or pinching).
   • The quick-connect or compression fitting at the head.
4. Check the nozzle. Make sure the nozzle opening isn't packed with debris blocking the airflow.

Dual Air: When Only One Stage Fails

If one stage blows fine but the other doesn't, you've narrowed it down a lot — the shared parts (pump, bulkhead, supply) are clearly working. The fault is in the parts unique to the dead stage: its relay, its JST connector and solenoid, its needle valve, or its hose branch up to the Y. Run Steps 1–3 on the dead stage and use the working stage as your known-good comparison for the lights and feel.

Common Mechanical Failures to Keep in Mind

Even when all the electrical signals check out, these mechanical parts can fail:

• Solenoid (internal): receives 24V but won't open.
• Needle valve (internal): opened up but won't pass air or lower portion of metal assembly of the needle valve is spinning with the adjustment knob.
• Hoses: holes from popping off under pressure or melting near the head; also simple disconnects at the bulkhead, the Y fittings, or the head.

Air Works on the Buttons but Not During a Job

If both stages blow when you press the test buttons but won't come on during an actual job, the air system itself is healthy — the machine just isn't being told to fire air during the job. That command comes from the DSP controller's signals to the TL Timer. Most often this is the layer's air-assist setting in your job file; if that's set correctly and air still doesn't fire on cue, contact support and mention that your test buttons work — that tells us to look at the controller's run signal to the TL Timer rather than the air hardware.

Quick Reference

Before You Contact Us

You'll get the fastest help if you've already:

• Fired both stages from the test buttons (or GT5 screen) and noted, for each: green light? pump running? air at nozzle?
• Noted which indicator lights came on (TL Timer, relay, green button).
• Checked the obvious connections — the 6mm bulkhead at the back, the head fitting, and the hose run through the drag chains.

Related Articles

• How To Adjust The Dual Stage Air Assist
• Selecting Between Low and High Dual Air Assist Stages in LightBurn
• Testing/Adjusting Peripheral Systems using the TL Timer
• Air Solenoid Differences
  
• How To Use A Multimeter

If you are a Thunder Laser USA client and still need Technical Support after exhausting the resources in the Knowledge Base, simply email support@thunderlaserusa.com and the Technical Support Team will promptly assist you! You can also use the form here.

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