A slim, fanless 40W supply built as a direct K40 replacement, with dual-voltage input and screw-terminal wiring. Order the right one of FONLAND's two versions and it drops into the stock bay.
FONLAND builds the MYJG-40W for both 110V and 220V mains. That printed voltage alone puts it ahead of a supply whose input nobody states. It is also the one setting that can kill a new supply in a second if it is wrong.
US and Canadian outlets run at roughly 110–120V. Most of Europe, the UK, Australia and much of Asia run at 220–240V. A supply set for 110V and fed 220V can fail the moment you flip the switch; one set for 220V and fed 110V usually just refuses to fire properly.
Voltage also shapes the ground check. Whatever your mains, the FG terminal on the supply goes to earth, and the K40's frame must share that earth. Many stock machines leave the factory with a thin ground path, so test from the frame to the plug's earth pin with a meter while everything is unplugged. The K40 tube and supply notes show how the stock wiring runs, and the K40 setup routine covers the ground check in context.
| Spec | Value |
|---|---|
| Model | MYJG-40W (L40W-B) |
| Output power | 40W |
| Output wattage | 40 watts |
| Input voltage | 110V/220V |
| Designed for | K40 laser engraving machines |
| Also fits | CO2 laser engravers and cutters |
| Connectors | Screw terminal, wire lead |
| Installation | Direct replacement design |
| Cooling | Natural convection |
| Enclosure | Enclosed case |
| Dimensions | 7.9 x 4.3 x 2.4 in |
| Weight | 2.2 lb |
| Sister model | MYJG 50W for 4060 and 6090 machines |
FONLAND uses screw terminals and wire leads rather than a fixed set of plugs. That makes the MYJG-40W forgiving: wires from an older supply with a different plug layout can land on the right terminals. It also means you must know which wire is which.
Start with the safety routine. Unplug the machine, wait several minutes, and discharge the tube's high-voltage terminal to chassis ground with an insulated grounding tool. A K40 supply produces the tens of thousands of volts a CO2 tube needs, and its output can stay charged after the plug is out.
Then move the wiring across in groups:
A loose control wire gives you a laser that will not fire. A loose high-voltage connection gives you arcing, which is far worse.
The MYJG-40W cools by natural convection. There is no fan inside to fail or to pull dust through the case, which suits a hobby machine that sits idle for days. It also means the supply depends on the air around it.
Placement rules for a convection-cooled supply:
The case is slim, which helps in a crowded K40 bay. Here is how it sits against the other 40W-class supplies:
| Supply | Case size | Weight | Cooling |
|---|---|---|---|
| FONLAND MYJG-40W | 7.9 x 4.3 x 2.4 in | 2.2 lb | Natural convection |
| DGHUNST Model A | 6.89 x 5.71 x 3.15 in | 1.19 kg | Air |
| OMTech MYJG-60 | 7.8 x 6.3 x 3.6 in | 4.6 lb | Not stated |
Measure your bay and the mounting holes before you order. If the holes do not line up, drill new ones in the bay floor rather than leaving the supply loose. A supply that slides around will eventually strain its high-voltage lead. Check also that the lid of the electronics bay still closes without pressing on any wire.
Heat is the slow killer of any laser supply. On long summer engraving runs, touch the case with the back of your hand after the job, once the machine is off and unplugged. Warm is normal. Too hot to hold means the bay needs more airflow, often just a small fan blowing across it.
FONLAND sells two supplies under the MYJG name. The MYJG-40W (L40W-B) is the K40 replacement. The other is a 50W supply for 4060 and 6090 machines, the larger CO2 lasers with bigger beds and longer tubes.
The 50W supply is not a K40 upgrade. A K40 bay takes a 700mm-class 40W tube, and 50W tubes are usually longer than that bay allows without cutting the case. A bigger supply on a 40W tube adds nothing but the ability to overdrive it. Stick with the L40W-B unless you are rebuilding the machine around a larger tube.
Compare it with the other 40W supplies before you commit:
Have three answers on the bench first: your mains voltage, a clear photo of your old supply's terminals, and proof that the fault is the supply. A tube that fires weakly with dirty mirrors is not a supply problem, so run the alignment checks first. Keep the mA meter in the circuit after the swap, since this supply has no display, and hold your 40W tube under its maker's current limit.
Yes. FONLAND builds it for 110V and 220V mains. Check the label or selector on your unit before the first power-up.
No. The 50W model targets 4060 and 6090 machines. A K40's 40W tube does not need it, and bigger tubes rarely fit the K40 bay.
No. Keep an analog mA meter in the tube's return lead to watch current.
It uses screw terminals and wire leads, so wires from a different plug layout can be landed on the matching terminals by function.