BAISULI K40 40W CO2 Laser Power Supply

Most K40s are built for one mains voltage and labelled for it. Find the label on the back or in the electronics bay before you order:

• 110V machine, US or Canadian outlet: the 110V version is your match.
• 220V machine, European, UK or Australian outlet: order the 220V version instead.
• Imported machine on the wrong mains: fix the machine's supply side properly rather than guessing, and match the new supply to what the machine is wired for.

A supply fed double its rated voltage usually fails at the first switch-on, sometimes loudly. One fed half its voltage may power up and then fire weakly, which looks like a tired tube and sends owners hunting for the wrong fault.

When the supply arrives, read its case label before you mount it. Mislabelled boxes happen, and a label check costs ten seconds. If the case carries a voltage selector as well, set it to match and photograph it.

Tape a note inside the bay with the voltage, so the next person who opens it does not have to guess. The K40 supply and tube notes explain how the mains, control and high-voltage sides connect.

Do not assume two Model A supplies from different makers are identical. Put a photo of your old supply next to BAISULI's and check each group by position and label:

1. Mains group: the two AC inputs and the FG earth terminal.
2. Control group: fire signal, water-protect, test switch and the power-control input from the pot or controller.
3. DC outputs: the 24V and 5V feeds to the controller board.
4. High-voltage lead: the thick red wire, and where it leaves the case.
5. Return: the terminal the tube's cathode lead comes back to, via the mA meter.

If one group sits in a different position, you re-terminate those wires to match function. Label each wire at the old supply with the name printed beside its terminal, and move them one at a time.

• Keep the old supply until the new one has run real jobs; it is your wiring reference.
• Do not cut connectors off until you have confirmed they cannot be reused.
• If the high-voltage lead will not reach the tube in one piece, stop and solve that first; never splice it.

At 4.41 pounds, the supply needs every mounting screw. A loose case shifts in use and pulls on the high-voltage lead where it enters the tube bay.

Before any power goes in, make the machine safe to work on:

1. Unplug the mains lead and keep it in view.
2. Give the capacitors several minutes to bleed down.
3. Use an insulated screwdriver on a lead clipped to chassis ground to discharge the tube's high-voltage terminal.

Then bring it up in this order:

1. Start the water and confirm it flows through the tube.
2. Close the lid, set the power pot or software limit low, and switch on.
3. Tap test-fire once. Watch the mA meter and listen at the case.
4. Raise the current in small steps, stopping well under your tube's rating. Your tube's data sheet gives the ceiling; for 40W glass tubes it is usually a figure in the high teens of milliamps.

A steady reading and a clean burn on tape at the first mirror mean the supply is doing its job. Crackling, a jumping needle or a burnt smell mean switch off, discharge and inspect the high-voltage run. The K40 operating routine covers glasses and fumes for the rest of the shake-down.

• DGHUNST Model A. The same layout letter, with 30W–40W tube coverage and separated input and output, but no stated input voltage. See the DGHUNST supply.
• FONLAND MYJG-40W. Marked 110V/220V, with screw terminals, convection cooling and published dimensions. See the FONLAND supply.
• OMTech MYJG-60. A larger 60W supply with an LCD that shows current and water-protect status. See the OMTech supply.

Choose BAISULI if your machine is on 110V, your old supply uses the Model A layout, and your bay has room for a case you will measure on arrival. BAISULI does not publish the case size, so ask BAISULI for it if your bay is cramped. The same goes for the mounting-hole pattern; drilling new holes in the bay floor is normal work, but plan for it.

Make sure the supply is the failed part before buying. A laser that will not fire is often an open water-protect circuit, a lid switch or an emergency stop. One that fires weakly is more often dirty optics or a drifted beam, which the K40 alignment steps will show. If the meter stays at zero with water flowing, interlocks closed and the lid shut, the supply is a fair suspect, and this is a reasonable replacement.

Tubes and supplies often age together. If your tube is years old and the old supply died, price a fresh 700mm tube at the same time and do both swaps in one session.