Hobart Welding Products TM-944C manual Theory of Operation

Page 20

SECTION 5 − THEORY OF OPERATION

1 Circuit Breaker CB1

Protects unit from an over-current condition by opening primary power line.

2 Power Switch S1

Turns unit and fan motor FM on and off.

3Fan Motor FM And Transformer

Controlled by power switch S1. Fan cools internal components, and transformer supplies control voltage to PC1.

4 Thermostat TP1

If unit overheats, TP1 opens stopping all weld output.

5 Gun Trigger Receptacle RC3

Connects gun trigger circuit to welding power source.

6 Control Board PC1

Controls weld output by connecting primary power to main transformer T1 through a board-mounted contactor that is activated by pressing the gun trigger. PC1 also regulates wire feed motor speed with a motor control circuit. Speed is set by feedback from Wire Feed Speed Control R1.

7 Gas Valve GS1

Controls shielding gas flow. Pressing gun trigger opens valve.

8 Wire Speed Control R1

Controls wire feed motor speed by providing a reference voltage to motor control circuit on PC1.

9 Range Switch S2

Allows selection of weld output voltage.

10 Main Transformer T1

Supplies power to weld output circuit.

11 Main Rectifier SR1

Changes the ac output from T1 to full-wave rectified dc output.

12 Output Capacitor C1

Smooths dc weld voltage from main rectifier SR1.

13 Stabilizer L1

Smooths dc weld current from main rectifier SR1.

14 Polarity Changeover Block

Terminals allow changing between DCEP and DCEN processes.

15 Wire Drive Motor

Feeds wire at a speed set by R1. Pressing gun trigger activates wire drive motor.

3	4	5
Fan Motor FM	Thermostat	Gun Trigger
And Transformer	TP1	Receptacle RC3

2

Power Switch

S1

		6
	1	Control Board
	1	PC1
	Circuit
Line	Breaker CB1
Line
L1
	Single-Phase
	Line Input
	Power
Neutral Line
(115 VAC Model)
	Line L2
(230 VAC Models)

7

Gas Valve

GS1

8

Wire Speed

Control R1

TM-944 Page 18

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Contents Description TM-944CProcesses Table of Contents Servicing Hazards − Safety Precautions for ServicingSymbol Usage California Proposition 65 Warnings EMF InformationRadiation can cause interference Overuse can cause OverheatingVAC Model − SpecificationsSpecifications Duty Cycle And Overheating OutputDuty Cycle % Output AmperesVolt-Ampere Curves − Installation Installing Welding Gun Installing Work ClampElectrode Negative For Flux Core Wire For Solid WireProcess/Polarity Table Changing PolarityInstalling Gas Supply Rating Label Grounded ReceptacleVolt, 20 ampere individual Up to 200 ft 61 mDo not move or operate unit where it could tip 18 in 457 mm of space for airflow= GND/PE L2 L1 230 VACElectrical Service Guide For 230 VAC Model Installing Wire Spool And Adjusting Hub Tension230 Reference 1996 National Electrical Code NECThreading Welding Wire Pressure Indicator ScaleBe sure that tip matches wire diameter Reinstall contact tip and nozzleVoltage Switch Power Switch− Operation ControlsWeld Parameter Chart For 115 VAC Model Starting Value only − Wire Speed Setting Can be Wire Speed Also Depends on Other variables Such Stick Out Electrode Positive For Solid Wire WhileWeld Parameter Chart For 230 VAC Model Listed Starting Value Only − Wire Speed Setting can be Metal Etc− Theory of Operation Block Wire Drive Motor Stablizer L1Main Polarity− Troubleshooting Troubleshooting TableGS1 if necessary Clear blockage in gunV8/R5 V9/R6 V10 V11/R9 TM-944030/.035 Solid 585Or Flux Core 640Test Equipment Needed Handler 135700 510600 Control Board PC1 Testing Information 115 VAC Model Control Board PC1 Test Point Values 115 VAC Model Circuit commonControl Board PC1 Testing Information 230 VAC Model Control Board PC1 Test Point Values 230 VAC Model − Maintenance Routine MaintenanceDisconnect power before maintaining Overload Protection Drive Motor ProtectionReplacing Gun Contact Tip Changing Drive Roll Or Wire Inlet GuideTurn Off power before replacing contact tip To Reassemble Gun Cleaning Or Replacing Gun LinerDisconnect gun from unit Replacing Switch And/Or Head Tube − Electrical Diagrams Model Serial Or Style Number Circuit Diagram Wiring Diagram194 324-C 194 325-A 196 637-A 196 655-A 195 890-A 195 891-A Handler 135 H-10 Gun − Parts List 11 10Dia Part Mkgs Description Quantity Optional 195 Optional Drive RollsOptions Hobart Welding Products