UBI EasyCoder 601 XP – Service Manual Ed. 1
86
Chapter 14 Power Supply
Booster Converter
The booster converter transforms the AC mains voltage to 385 V
DC by sensing the shape of the curve of the mains voltage and
chopping it to short pulses, where the pulse amplitude follows the
shape of the curve. The booster is protected by two 3.15 A fuses.
Forward Converter
The forward converter transforms 385 V DC to 24 V DC 0.3–5 A
and 42 V 0.1–0.9A. The 24 V is used for the thermal printhead and
the optional cutter unit and the 42 V is used for the stepper motor(s).
The potentiometer R89 is used to trim the 24 V. Note that the 24 V
must be loaded with at least 0.3 A before the voltage is stable enough
to allow trimming.
Buck Converter
The buck converter transforms 24 V DC to 5.3 V DC 0.3 – 3 A
which is used for the logics. On power supply unit 1-971601-27, the
5.3V can be adjusted by means of the potentiometer R146.
Fan
The cooling fan at the bottom of the power supply unit is controlled
by a thermostat on the primary side cooler and will improve cooling
and spread the heat in the entire machine to avoid local high
temperatures.
Connections
X1
Mains supply >90 – <240 V AC, 45 – 65 Hz
X2
Power to thermal printhead
X3
Power to CPU board
X4
Power to PSU fan
Miscellaneous
The power supply unit is also fitted with a switch that can shut off
the 24 V to the printhead and cutter and a Power Fail Interrupt (PFI)
signal that warns the logics that the power is about to be shut off.
The high voltage and low voltage parts of the PSU is divided by a
thick white line printed on the circuit board.
Troubleshooting
All voltages are available on test points on the CPU board, see
chapter 15.5. If all voltages are present, but the 24 V is too high or
low, load with at least 0.3 A and trim on R89.
Jarring sounds or repeated overheating interrupts at high-load
printing (e.g. large black areas) in an otherwise faultless power
supply indicates that the cooling fan may need to be replaced. It is
fitted at the bottom of the PSU with four plastic screws and
connected to X4.
If a fuse is blown, do not try to repair the PSU, but replace the
entire unit!
14.1 Description,
cont'd.
