- 4 -
TECNICA 1400 - 1600
Block 15
Dutycyclemaker
Consistingof: U2 (controlboard) = UC 3845
Processes the information from block 16 (adder) and
block 14 (primary current reader) and produces a
square wave with variable duty cycle limiting the
primarycurrenttoamaximum pre-set value under all
circumstances.
Block 16
Adder
Consistingof: U1D (controlboard)
Gathers all the information from block 14 (primary
current reader), from block 17 (alarms) and from
block 18 (potentiometer), and produces a signal with
a suitable voltage for processing by block 15 (duty
cyclemaker).
Block 17
AlarmBlock
Consistingof: U1A, U1C (controlboard)
When an alarm is detected the machine output
current is drastically reduced by directly adjusting
and changing the reference signal obtained from
block18(potentiometer).
Block 18
Potentiometer
Consistingof: R7
Thisisusedtocreatethereferencevoltageneededto
adjust the output current: when the potentiometer is
turned the cursor voltage varies, thus varying the
currentfromtheminimumtothemaximumvalue.
Block 19
YellowLEDalarmlight
Consistingof: D26 (yellow)
Itisswitchedonbyblock17(alarms)intheeventof:
1) Triggering of thermostatic capsule on power
transformer.
2) Triggeringduetoundervoltage.
3) Triggeringduetoovervoltage.
4) Short circuit at output (electrode holder and earth
cable connected to each other or electrode stuck
topiecebeingwelded).
Block 20
Maximumcurrentadjustment
Consistingof: R32, R33, R42
Used to adjust the maximum welding current
suppliedbythepowersource.
Block 21
Powertransformerthermostat
Consistingof: ST1 thermostatic capsule.
When the temperature of the power transformer is
too high, this safeguard is triggered. It is reset
automaticallyafterthealarmconditionhasceased.
Block 22
Galvanicseparator
Consistingof: ISO1
The signal from the thermostatic capsules is
separated galvanically and sent to block 17 (alarms)
foridentificationofpossiblealarmcondition.
Block 23
Overvoltagesafeguard
Consistingof: R3, R4 andpartofthecontrolsection
If the main supply voltage exceeds the maximum
value this safeguard triggers (a tolerance of approx.
±15% of the power supply voltage is allowed:outside
thisrangethesafeguardtriggers).
Block 24
Undervoltagesafeguard
Consistingof: R5, R6 andpartofcontrolboard
If the main supply voltage falls below the minimum
allowed value this safeguard triggers (a tolerance of
approx.±15% of thepower supply voltageis allowed:
outsidethisrangethesafeguardtriggers).
Block 25
PowersupplyLED
Consistingof: D2
Shows that the machine is correctly powered and
readytoweld.
On machines operating exclusively at 230V it is
green.
Block 26
Fan
Cools the power components. On machines
operatingexclusivelyat230Vitispowereddirectlyby
block12 (at 12V).
