Lincoln Electric SVM161-A CONTROL/DISPLAY Board, High Frequency HF Board, Output Filter Board

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E-5 THEORY OF OPERATION E-5

FIGURE E.5 - CONTROL/DISPLAY BOARD, HF BOARD & OUTPUT FILTER BOARD

Fan

Superimposition

board

24 VDC

Bus board

AC DC Gate drive signals

Input

HF

board

board

Voltage Feedback

15,+5-+24,+15,48,-

.inforeconnect

ckt.AConturn

supplyvolthigh

feedbackvoltage

feedbackcurrent

Current Feedback

Output

IGBT

Diode

Thermostat

Output

Thermostats

Filter bd.

(bypass)

Main IGBT

& Power board

4

_

IGBT's

Output

RF coil

Choke

+

infothermostat

metervoltinput

metercurrentinput

DC blocking

Current

.cktAConturn

+515,-+15,

infoset

PWMonturn

capacitor board

Input

Hall

Main

Output

Choke

Output

Device

Transformer

board

Transistor

Module

24 VDC Remote 2/4 path (D + E)

HF control signal

888

+48, +24

Control board

Display & LED

board

Control	(D + E)
	Remote 2/4
Knob

Remote

48 VDC75, 76, 77 A, B, C

Gas

Solenoid

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CONTROL/DISPLAY BOARD

The Control/Display Board assembly is actually two boards mounted together. They should be replaced together. The Display portion houses the control panel, LEDs, push buttons and output encoders. The Display Boards functions as the interface between the user and the V205-T machine.

The Control Board functions as the support circuitry for the on board CPU (micro-processor). The Control Board receives information and power from the Bus Board, and Main IGBT Inverter Board. The Control Board supplies power for the Display Board and sup- plies signals for the Display Board to show set and actual current values, error codes and pre-set values. It also accepts signals via the Output Filter Board (Pins D and E- 24VDC) to initiate welding output. Upon clo- sure of D and E a 24VDC relay is activated to indicate that welding output is required. The Control Board CPU sends a command to the Main IGBT Inverter Board to activate the welding IGBTs. The remote con- trol signals (Pins A, B&C) are also fed into the Control/Display Board from the 6 pin connector located on the front of the machine. Based upon current and voltage feedback information the Control Board regu- lates the welding output to coincide with the pre-set welding commands. The Control/Display Board also activates and controls the High Frequency Board, the gas solenoid and the Super Imposition Board.

HIGH FREQUENCY (HF) BOARD

The HF Board generates a set of pulses of about 900V, which are amplified through the high voltage trans- former to about 8 to 10KV. These pulses that are repeated at a frequency of about 80HZ are applied to the high frequency transformer that is located in the negative welding output leg of the machine. This high frequency pulse is transferred to the TIG torch via the high frequency transformer. This allows the remote starting of the TIG arc without the need for the tungsten electrode to touch the work. This high frequency pulse is removed when the welding arc is established.

The command signals are received from the micro- processor on the Control Board and last for about 1 second maximum. The HF Board receives it’s power from the + 385 VDC derived from the electrolytic capacitors on the Main IGBT Inverter Board.

OUTPUT FILTER BOARD

This PC board, located at the welding output terminals protects the internal circuitry of the machine from high voltage and high frequency pulses that may be fed back into the unit via the welding cables, torch cable or remote control equipment. This unwanted “noise” is shunted to case ground.

NOTE: Unshaded areas of Block Logic

Diagram are the subject of discussion

INVERTEC® V205-T AC/DC™