Block
diagram and descriptions
Block 1: EMC Filter
Consisting
of: C1, C2, C3, L1.
Prevents noise from the machine from being transmitted along
the main power line and vice versa.
Prevents noise from the machine from being transmitted along
the main power line and vice versa.
Block 2: Pre-charge
Consisting
of: K1, R1.
Prevents the formation of high transitory currents that could damage the main power switch, the rectifier bridge and the electrolytic capacitors.
When the power source is switched on the relay K1 is deenergised, capacitors C4, C5, C6, C7, C8 are then charged by R1. When the capacitors are charged the relay is energized.
Prevents the formation of high transitory currents that could damage the main power switch, the rectifier bridge and the electrolytic capacitors.
When the power source is switched on the relay K1 is deenergised, capacitors C4, C5, C6, C7, C8 are then charged by R1. When the capacitors are charged the relay is energized.
Block 3: Rectifier Bridge
Consisting
of: D1.
Converts the mains alternating voltage into continuous pulsed voltage.
Converts the mains alternating voltage into continuous pulsed voltage.
Block 4: Filter
Consisting
of: C4, C5, C6, C7.
Converts the pulsed voltage from the rectifier bridge into continuous voltage.
Converts the pulsed voltage from the rectifier bridge into continuous voltage.
Block 5: Chopper
Consisting
of: Q1, Q2, Q3, Q4.
Converts the continuous voltage from the filter into a high frequency square wave capable of piloting the power transformer.
Regulates the power according to the required welding current/voltage.
Converts the continuous voltage from the filter into a high frequency square wave capable of piloting the power transformer.
Regulates the power according to the required welding current/voltage.
Block 6: Current transformer
Consisting
of: T2.
The C.T. is used to measure the current circulating in the power transformer primary and transmit the information to block 14 (primary current reader and limiter).
The C.T. is used to measure the current circulating in the power transformer primary and transmit the information to block 14 (primary current reader and limiter).
Block 7: Power transformer
Consisting
of: T3.
Adjusts the voltage and current to values required for the welding procedure. Also forms galvanic separation of the primary from the secondary (welding circuit from the power supply line).
Adjusts the voltage and current to values required for the welding procedure. Also forms galvanic separation of the primary from the secondary (welding circuit from the power supply line).
Block 8: Secondary diodes
D20,
D21 converts the current circulating in the transformer to a single direction,
preventing saturation of the nucleus.
D22, D23 recirculate the inductance output current (block 9) when the
IGBT's are not conducting, bypassing the power transformer (block 7).
Block 9: Inductance
Consisting
of: L2.
Levels the secondary board diodes’ output current making it practically continuous.
Levels the secondary board diodes’ output current making it practically continuous.
Block 10: Secondary EMC filter
Consisting
of: C21, C22.
Prevents noise from the power source from being transmitted through the welding cables and vice versa.
Prevents noise from the power source from being transmitted through the welding cables and vice versa.
Block 11: Flyback power supply
Consisting
of: T1, U2.
Uses switching methods to transform and stabilise the voltage obtained from block 4 (filter) and supplies auxiliary voltage to power block 12 (driver) and the control board correctly.
Uses switching methods to transform and stabilise the voltage obtained from block 4 (filter) and supplies auxiliary voltage to power block 12 (driver) and the control board correctly.
Block 12: Driver
Consisting
of: ISO2, ISO3.
Takes the signal from block 11 (flyback power supply) and, controlled by block 14 (duty cycle maker), makes the signal suitable for piloting block 6 (chopper).
Takes the signal from block 11 (flyback power supply) and, controlled by block 14 (duty cycle maker), makes the signal suitable for piloting block 6 (chopper).
Block 13: Primary current reader and limiter
Consisting
of: R63, R64, R65 and part of the control section. Reads the signal from block 6 (current
transformer) and scales it down so it can be processed and compared in blocks
14 and 15.
Block 14: Duty cycle maker
Consisting
of: U2 (control board).
Processes the information from block 15 (adder) and block 13 (primary current reader and limiter) and produces a square wave with variable duty cycle limiting the primary current to a maximum pre-set value under all circumstances.
Processes the information from block 15 (adder) and block 13 (primary current reader and limiter) and produces a square wave with variable duty cycle limiting the primary current to a maximum pre-set value under all circumstances.
Block 15: Adder
Consisting
of: U1C (control board).
Gathers all the information from block 13 (primary current reader and limiter), from block 16 (alarms) and from block 18 (current potentiometer), and produces a signal with a suitable voltage for processing by block 14 (duty cycle maker).
Gathers all the information from block 13 (primary current reader and limiter), from block 16 (alarms) and from block 18 (current potentiometer), and produces a signal with a suitable voltage for processing by block 14 (duty cycle maker).
Block 16: Alarm block
Consisting
of: U1A, U1B (control board).
When an alarm is detected the power source output current is drastically reduced by making direct adjustments to block 14 (duty cycle maker) and directly changing the reference signal obtained from block 18 (current potentiometer).
When an alarm is detected the power source output current is drastically reduced by making direct adjustments to block 14 (duty cycle maker) and directly changing the reference signal obtained from block 18 (current potentiometer).
Block 17: alarm LED
Consisting
of: D14.
It is switched on by block 16 (alarms) in the event of:
1) Triggering of thermostatic capsule/thermostat on power transformer.
2) Triggering due to undervoltage.
3) Triggering due to overvoltage.
4) Short circuit at output (electrode holder clamp and earth cable connected to one another or electrode stuck to piece being welded).
It is switched on by block 16 (alarms) in the event of:
1) Triggering of thermostatic capsule/thermostat on power transformer.
2) Triggering due to undervoltage.
3) Triggering due to overvoltage.
4) Short circuit at output (electrode holder clamp and earth cable connected to one another or electrode stuck to piece being welded).
Block 18: Current potentiometer
Consisting
of: R52.
This is used to set the reference voltage needed to adjust the output current: when the potentiometer knob is turned the cursor voltage varies, thus varying the current from the minimum to the maximum value.
This is used to set the reference voltage needed to adjust the output current: when the potentiometer knob is turned the cursor voltage varies, thus varying the current from the minimum to the maximum value.
Block 19: max; current adjustment
Consisting
of: R56, R57, R58.
Used to adjust the maximum cutting current to be supplied by the power source.
Used to adjust the maximum cutting current to be supplied by the power source.
Block 20: Power transformer thermostat
Consisting
of: ST1.
When the temperature of the power transformer is too high, the thermostat transmit the information to block 21 (galvanic separation). It is reset automatically after the alarm condition has ceased.
When the temperature of the power transformer is too high, the thermostat transmit the information to block 21 (galvanic separation). It is reset automatically after the alarm condition has ceased.
Block 21: Galvanic separator
Consisting
of: ISO1. The signal arriving from
blocks 20 and 21 (power transformer thermostat and secondary diodes) is separated
galvanically and sent to block 16 (alarms) for detection of a possible alarm
event.
Block 22: Overvoltage safeguard
Consisting
of: R71, R73 and part of the control section.
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 this range the safeguard triggers).
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 this range the safeguard triggers).
Block 23: Under voltage safeguard
Consisting
of: R72, R70 and part of control board.
If the main supply voltage falls below the minimum allowed value this safeguard triggers (a tolerance of approx. ±15% of the power supply voltage is allowed: outside this range the safeguard triggers).
If the main supply voltage falls below the minimum allowed value this safeguard triggers (a tolerance of approx. ±15% of the power supply voltage is allowed: outside this range the safeguard triggers).
Block 24: Power supply identification 115/230V
Consisting
of: U1A, Q2, Q1 (voltage change board).
This is only present on machines with the automatic identification function.
Identifies the power supply voltage level (115V or 230V) and compares the values with a reference signal. The comparison causes enabling of block 5 (filter) for operation in standard mode (230V) or as voltage duplicator (115V). This block also adjusts for the correct maximum current in relation to the different operating modes.
This is only present on machines with the automatic identification function.
Identifies the power supply voltage level (115V or 230V) and compares the values with a reference signal. The comparison causes enabling of block 5 (filter) for operation in standard mode (230V) or as voltage duplicator (115V). This block also adjusts for the correct maximum current in relation to the different operating modes.
Block 25: Power supply LED
Consisting
of: D12 (D13 for Tecnica 152).
Indicates when the power source is correctly powered and ready for use.
On machines operating exclusively at 230V it is green. On machines with automatic voltage identification (Tecnica 152) it is green for operation at 230V and orange for operation at 115V.
Indicates when the power source is correctly powered and ready for use.
On machines operating exclusively at 230V it is green. On machines with automatic voltage identification (Tecnica 152) it is green for operation at 230V and orange for operation at 115V.
Block 26: Fan
Consisting
of: V1.
Powered directly by block 13 (power supply) and cools the power components.
Powered directly by block 13 (power supply) and cools the power components.
Troubleshooting details and schematic – by next post
