SERVICE MANUAL
KEMPACT RA_V_1.2
13 (40)
Kemppi Oy
3.1. Main components
3.1.1. Terminal block X001
• Mains cable is connected to the terminal block X001. The terminal block is located in the mains cable connection box
on the back plate of the machine. Also varistors R001 are connected to this terminal block. From the terminal block
mains voltage is wired to main switch S001
3.1.2. Varistors R001
• The varistors are located in the mains cable connection box on the backside of the welding machine
• The purpose of the varistors is to protect the welding machine against voltage spikes coming from the mains
3.1.3. Main switch S001
• The main switch is located in the upper part of the machine close to the user interface
3.1.4. Terminal block X009
• From the main switch S001 mains voltage is wired to terminal block X009 which is located on the front side of the
component frame. From this terminal block mains voltage is wired to the main circuit card Z001
• PE (protective earth) is wired from this terminal block into the component frame and connected to a chassis ground
terminal
3.1.6. Test connector X006
• Possible to measure DC-link voltage during service
3.1.7. Auxliary transformer T002 and rectifier bridge G003
• Auxliary transformer is a 60VA toroidal transformer
• It has 230V and 400V inputs and 18V output
• 230V input is used in 181 and 251 machines
• 400V input is used in 253 and 323 machines
• Auxliary transformer output voltage is rectified using rectifier bridge G003. Both the auxiliary transformer and the
rectifier bridge are located inside the component frame
3.1.8. Control card A001
• All machines have different type of control card according machine size and type.
• MVU card has +24V aux power which regulates +24V when input voltage changes (+24V aux power components are
not installed on MVU control card).
3.1.8.1. Auxiliary power supply
• Auxliary voltage +24V is used by fans, gas valve, inrush relay and brights LED. This voltage is also used to drive opto-
coupler that enables PFC and panel backlight. To generate +24V voltage auxliary transformer T002 output is full wave
rectified using rectifier bridge G003
• Auxliary voltage +15V is used by IGBT driver (V20, V22, V23, V25 etc.), PWM IC (N5), motor control half bridge driver
(N2) and other circuits
• Auxliary voltage +5V is used by microcontroller N7, panel card P001 and other circuits
3.1.8.2. Microcontroller
• Many of the control card A001 functions are using the microcontroller N7. Basic functions of the microcontroller
include controlling output voltage of the inverter. The microcontroller measures output voltage and changes peak
current reference of the inverter to regulate it
• The microcontroller also regulates wire feed speed by setting motor current reference and measuring EMF of the
motor
3.1.8.3. Motor control
• Wire feed motor control is based on EMF (electro magnetic force) measurement principle
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