14 - Microprocessor Supply Voltage Error On Control Board (543); 16 - Direct Current Voltage At Pre-Charge Board (562) Output Below Minimum Permitted Value; 20 - Absence Of Interlock Signal On Ta Board (558); 25 - Error On The Epld Bus In The Control Board (543) - Cebora SOUND MIG 3840/T Pulse Service Manual

CEBORA S.p.A.

3.7.6 - 14 - Microprocessor supply voltage error on control board (543).

Perform the CONTROL BOARD (543) POWER SUPPLY TEST in par. 3.5.2, paying special
attention to the 8 Vdc and 5 Vdc voltages.
3.7.7 - 16 - Direct current voltage at pre-charge board (562) output below minimum
permitted value.
This alarm is operative only at the power source start-up.
The direct current voltage on the DC-capacitors (561) is not sufficient to ensure proper
operation of the inverter, and thus of the power source. This may be due to a possible distortion
of the mains voltage (or of a single phase of the mains voltage), a short-circuit, or strong
absorption from DC-capacitors (561) or igbt (548) modules, or a fault in the pre-charge board
(562), or in the built-in rectifier bridge.
Perform the test of par. 3.5.1.

3.7.8 - 20 - Absence of interlock signal on TA board (558).

The "interlock" signal is provided by a jumper between terminals 3 and 4 of J1 on TA board
(558), and is used to make sure that the TA board (558) is connected to the control board (543)
(current feedback signal line to the primary circuit of the transformer (531)).
Check the wiring between terminals 3 and 4 of J1 on TA board (558) and terminals 8 and 7 of
J1 on micro board (543).
Make sure that there is a short-circuit between terminals 3 and 4 of J1 on TA board (558).
With power source off, temporarily disconnect connector J1 from micro board (543).
Power up the power source again and check the supply voltage on J1 of micro board (543),
terminals 8(+) and 7(-) = +5 Vdc. If incorrect, replace control board (543).
Replace the control (543) and/or TA (558) boards.

3.7.9 - 25 - Error on the EPLD bus in the control board (543).

This code calls up various problems that may occur in controlling the igbt inverter (548).
Generally they are those defects that cause a high absorbed current in the primary circuit of the
transformer (531), due for example to a short-circuit in the windings of the transformer (531) or
in the diode group (567).
For an analysis of the problem, see "open circuit operation" par. 3.5.8 and "operation on
resistive load" par. 3.5.9.

3.7.10 - 30 - Incorrect setting of the minimum current threshold on control board (543).

CONTROL BOARD (543) MINIMUM CURRENT THRESHOLD SETTING.
Micro board (543), connector J1, terminal 3(+) and 5(-) = +360 mVdc, +/- 10 mVdc with
power source powered but not delivering current.
♦ With power source off, temporarily disconnect J1 from micro board (543) and
check the resistance on terminals 3 and 5 of J1 on micro board (543) = 17 ohm. If
incorrect, replace control board (543).
♦ Adjust trimmer TR1 on micro board (543) to have 360 mVdc +/- 10 mV.
♦ Replace control board (543).
♦ Regular operation.
3.302.191
Correct?
YES
NO
37
15/02/05