The Haas 320V Power Supply
The Haas high voltage power supply (MMPS) is the source of power for the servo amplifiers. It rectifies 3-phase 208 VAC or single-phase 240 VAC and supplies 320 to 340 VDC to the amplifiers. The same unit carries the regeneration circuit used for dynamic braking.
Haas lists the 32-5557, 32-5566, and 32-5566A versions of the 320V power supply. One independent shop lists repairs for Haas 320V power supply models 69-2000A, 69-2000D, and 32-5556/32-5557. Board repair shops list the Haas 65-4075G power supply board.
Haas Power Supply Repair Shops
CNC Service Company
Marinette, WI
Brands: Haas
Control System Labs
Buffalo, NY
Brands: Haas
Alarms That Point to the Power Supply
Alarm 648 DC BUS SHORTED together with alarm 160 LOW INCOMING AC LINE VOLTAGE points to the DC bus or a shorted MMPS. Haas ties alarm 647 REGEN LOAD SHORTED to the regen load or a shorted MMPS. With alarm 119 INPUT AC LINE OVERVOLTAGE and alarm 650 DC BUS OVER VOLTAGE the cause is the regen load or a faulty MMPS.
A wrong DC bus reading on the control can come from low incoming line voltage or a voltage monitor cable that is not connected correctly. The 320V power supply puts out roughly 1 VDC on that monitor signal for every 100 VAC. A supply that does not is defective.
Isolating the Fault
Haas compares the DC voltage at pins 1 and 2 of connector J4 on the MMPS with the DC VOLTAGE on the control’s diagnostics page. The two readings must match within 2 percent. With the DC bus cables off connector J3 a DC bus that returns to its nominal value points to a short in one of the servo amplifiers.
A meter on resistance from terminals 1, 2, and 3 to chassis ground should read an open circuit on a good MMPS. The regen load should measure between 9.5 and 12.5 ohms across its leads. Haas requires the high voltage light to be off for at least 5 minutes before work starts inside the cabinet. Discharging the 32-5566A with a resistor blows its fuse.