Alarm Signals; Lamp (G) (39) Lit, With Fix Light = Transformer (38) Temperature Above The Limit; Lamp (G) (39) Flashing (One Flash With One Second Pause) = Arc Voltage Lower Than Working Minimum Threshold - Cebora 961 Service Manual

CEBORA S.p.A.

3.4 - Alarm signals.

3.4.1 - Lamp (G) (39) lit, with fix light = transformer (38) temperature above the limit.

Power source remains in block with contactors TLP (32) and TLM (32) opened.
We recommend not to shut off the power source, to keep the fan (34) running and thus allow
rapid cooling.
This is reset automatically when the temperature returns within the allowed limits.
Thermostat in reality is made by two thermostatic switches connected in series between them,
located on two columns of the transformer (38).
To analyze the problem perform the following test.
THERMOSTAT ON TRANSFORMER (38) TEST.
Control board (4), connector J6, terminals 6 and 7 = 0 Vac, contact closed, with transformer
(38) at ambient temperature; 24 Vac, contact opened, with temperature excessive.
♦ Check the wiring between thermostats on transformer (38) and terminals 6 and 7
of J6 on control board (4), considering that in reality thermostatic switches are
two, series connected between them.
♦ Make sure that the two thermostatic switches are intact and properly positioned on
the windings of the transformer (38).
♦ If the alarm occurs while cutting, and the transformer (38) is evenly heated, make
sure that the duty-cycle is not greater than indicated in the power source
specifications.
♦ If the alarm occurs while cutting, and only some of the windings of the
transformer (38) are heated, one may infer that the transformer (38) is partially
short-circuited, and must therefore be replaced.
♦ Replace thermostat on transformer (38).
♦ Replace control board (4).
3.4.2 - Lamp (G) (39) flashing (one flash with one second pause) = arc voltage lower than
working minimum threshold.
Usually is due to a short-circuit or excessive load at the power source output, so that the
output voltage falls down 40 Vdc. Control board (4) detects such signal (connector J7, terminals
1(+) and 4(-)) and commands power source block, with contactors TLP (32) and TLM (32)
opened.
This is reset by turning off the power source.
At the origin of the problem you can hypothesize that the electrode and nozzle short-circuit
lasts to much, caused by firing ram in the torch blocked in extended position, or electrode and
nozzle attachment, or short-circuit in the torch cable, or else an overload during cutting caused
by a wrong use of the torch over the work piece.
Check the wiring between J7 on control board (4) and electrode and nozzle torch cable
terminals on terminal board (31). An eventual interruption of this connection may cause this
alarm.
3.302.170
Correct?
YES
NO
16
06/07/04