78 - "Gas""Lo" On Displays (U) (V). Gas Low Pressure; 99 - "Off" On Display (U). Incorrect Mains Voltage (Machine Shutdown) - Cebora PLASMA PROF 123 ACC Service Manual

CEBORA S.p.A.

3.4.14 - 78 - "GAS""LO" on displays (U) (V). Gas low pressure.

This alarm signals that plasma gas pressure is below the minimum value allowed for a correct
operation. The pressure signal is supplied by the pressure switch (15).
PRESSURE SWITCH (15) TEST.
Control board (47), connector J12, terminals 5 and 6 = 0 Vdc, pressure switch contact closed
= suitable pressure; 27 Vac, pressure switch contact open = pressure low).
♦ Check the wiring between pressure switch (15) and J12, terminals 5 and 6 on
control board (47).
♦ Check the supply voltage of the control board (47) taking special care for 27 Vac
voltage carrying out the CONTROL BOARD (47) POWER SUPPLY TEST of
par. 3.3.1.
♦ With Power Source off, temporarily disconnect the wires from pressure switch
(15) terminals. Power up the Power Source again and check on the patch
connector disconnected from pressure switch (15), voltage = 27 Vac, with switch
(49) closed (alarm condition). If incorrect, replace control board (47).
♦ Check for pressure switch (15) integrity, varying, with knob (L), the gas plasma
pressure, during the post gas phase (that is with the gas flowing out from the
torch). The pressure switch (15) contact must opens for a pressure value of
approximately 3.2 bars, read on the regulator (L) gauge. If defective replace it.
♦ Make sure that gas lines are not clogged where pressure switch (15) is connected.
♦ Replace pressure switch (15) and/or control board (47).
♦ Replace control board (47).

3.4.15 - 99 - "OFF" on display (U). Incorrect mains voltage (machine shutdown).

This message appears normally, and briefly, each time the Power Source is shut off.
When mains voltage is missing, for example after the switch (49) opening, all control circuits
remain powered for a few seconds due to the effects of the capacitors charge in the various
boards power feeders.
The supply board (51) detects the control board (47) supply voltage decreased (for instance
failed mains voltage), transfers it to control board (47) ("UV" signal on connector J2 of control
board (47)) that stops the Power Source with the "OFF" indication shown on display (U).
The "UV" signal may be tested on J3 of supply board (51), on terminals 1(+) and 2(-);:0 Vdc
= mains not suitable; +1.1 Vdc approximately = mains suitable.
If correct replace control board (47).
If not correct, with Power Source off, temporarily disconnect J3 from supply board (51) and
check the resistance between terminals 1 and 2 of the patch connector disconnected from J3 of
supply board (51). Correct value = junction of two diodes in both measure directions. If
incorrect, replace control board (47). If correct replace the supply board (51).
Carry out the tests of par. 3.3.1 and replace the supply board (51) and or control board (47) if
necessary.
3.302.269
Correct?
YES
NO
32
12/04/2012