Troubleshooting
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02.20
909.2710.1-06
9.9
Monitoring primary input current
The input current of the power units is monitored at the DCDR pcb. The current that is flowing through the
primary coils of the welding transformer is measured with an internal current sensor. As soon as the cur-
rent is exceeding the maximum value, the CPLD (= Complex Programmable Logic Device) on the MAPRO
shuts down the power unit immediately.
The S5 and S8 / P4500 and P5500, the weld energy is generated with two power units at the same time.
The S3 and S3 mobile / P3500 and P3000 mobile only have one power unit.
Schematic
If power unit 1 draws too much current, the machine will stop and displays
E16
(primary overcurrent pro-
tection1) : red LED on DCDR unit1 is on.
If power unit 2 draws too much current, the machine will stop and displays
E24
(primary overcurrent pro-
tection2) : red LED on DCDR unit2 is on.
For example: E16 (primary overcurrent protection1)
possible reasons could be:
–
power unit 1 is faulty (like short circuit at MOSFET)
–
power unit 2 is not active (if driver signals for the second power unit are missing or the DCDR pcb
of power unit 2 is malfunctioning) In this case power unit 1 has to generate all the weld energy by
itself. Which is possible to a certain amount of power (200A to 250A) but beyond that, the unit will
stop with E16
–
malfunction at DCDR pcb of power unit 1 (e.g. optocoupler output malfunction)
–
bad flat ribbon cables between MAPRO pcb and power units
–
short circuit at output diodes
There is a simple way to find out if the power unit itself is bad or not (only possible at S5 or S8): exchange
the flat ribbon cables at the MAPRO pcb against each other (connectors X1 and X4) so that power unit 1
becomes power unit 2 and vice versa. If the machine now shuts down with E24 (Overcurrent protection 2)
instead of E16, the power unit itself is faulty.
If the E16 should still remain, it is very likely that the MAPRO pcb is faulty.
Another reason for a primary overcurrent is a short circuit at the output (secondary side). If for example
one of the output diodes has a short circuit, no output voltage (open circuit voltage) can be created. In
this case the machine reacts with E16 (at S3, S3 mobile / P3500, P3000 mobile) or with E24 (at S5, S8 /
P4500, P5500).
Similarly, E16 / E24 can be triggered if the VAC current sensor is still mounted in the “old” position, but
the software is already version 3.05 or newer (see “New VAC position” on page 45).
