ESAB SVI-450i/DP - 450i Power Board Balancing Troubleshooting instruction

Brand: ESAB

Model: SVI-450i/DP - 450i Power Board Balancing

Category: Power adapters & inverters

Type: Troubleshooting instruction

Important:

• Power boards must be replaced in matched pairs and

balanced.

• Care must be taken not to damage the Kapton insula-

tion between the isobar and heatsink.

Equipment Needed:

• Potentiometer adjustment tool.

• Two Digital Multimeters with a resolution of at least 3 1/

2 digits.

• Remote Hand Control HC-3B or HC-4B.

• Input Power Source: Highest line (up to 506 VAC, 60Hz)

• Shorting cable, 15’ #8 AWG cable with male twist lock

connector (PN - 1373-3936) on both ends.

Procedure:

1. Remove the top and side covers of the power sup-

ply.

2. Locate the Input Voltage Terminal Board next to the

Inverter Control Board (ICB) at the top of the ma-

chine. Verify that the unit is strapped for 460 VAC

input and re-strap if necessary.

3. Locate the Inverter Power Boards on which are

mounted 16 MOSFETs per board. These boards are

located toward the front of the machine on either side.

While facing the front of the machine, the Power

Board on the left will be referred to as PB I and the

Power Board on the right is called PB2. (see Fig. 1)

4. Find two potentiometers (R8 and R28) which are both

located on each Power Board. These potentiometers

are located a little less than half way down from the

top of both PB 1 and PB2. (see Fig. 2)

INSTRUCTIONS for

F-15-593-B

November, 2003

SVI-450i/DP - 450i Power Board Balancing

P/N 674991

Electric shock can kill! Precautionary measures should be taken to provide maximum protection against electrical

shock. Be sure that all power is off by opening the line (wall) disconnect switch or circuit breaker before attempting

any inspection or work on the inside of the power source.

PB1

PB2

Potentiometers

(R8 & R28)

5. Measure the resistance of these potentiometers with

an ohmmeter and adjust each one to 5 ohms. Po-

tentiometer R8 can be measured by placing an ohm-

meter between the drain of Q3 (see Fig. 3) and the

gate resistor R10. Potentiometer R28 can be mea-

sured by placing the ohmmeter between the drain of

Q14 and the gate resistor R31. If the ohm meter

being used contains a relative option, then a more

accurate reading can be gotten by putting the multi-

meter in ohm mode; connecting the meter leads to-

gether, and pressing the relative button on the meter.

This preceedure zeros out the resistance effect of

the leads.

Fig. 1 - Location of Power Boards

Fig. 2 - Location of Potentiometers

F-15-593-B 11/2003

6. Place one of the voltmeters across capacitor C6 on

PB1 and the other across C6 on PB2. (see Fig. 4)

7. Short circuit the power supply by using a 15' 8 AWG

cable to connect the positive output of the power

supply to the negative output.

8. Connect the Remote Hand Control to the power sup-

ply by means of the 14-pin receptacle at the rear

panel of the machine marked “Remote Control”. Turn

the Output pot on the Remote Hand Control full

counter clockwise to “Minimum” for minimum cur-

rent (if an HC-4B is used, turn the Arc Force pot to

minimum also). Make sure the contactor switch is in

the “Off’ position and the CC/CV switch is in the “CC

(Stick/Tig)” mode.

9. Turn the Main Power switch on the rear of the ma-

chine to the “ON” position. Then turn the Contactor

switch on the Remote Hand Control to the “ON” po-

sition. At this time, the power supply should be put-

ting out power. Adjust R160 the Inverter Control Board

(ICB) until the short circuit output current is between

90 and 110 amps.

10. Check the voltages across C6 on PB1 and PB2. No

calibration is required if the voltage difference be-

tween the two boards is 15 volts or less. If the volt-

age difference is greater than 15 V go on to the next

step.

11. Make sure the power to the machine is off and

allow the voltage across capacitors C6 on PB1

and PB2 to bleed down to less than 10V before

readjusting the potentiometers. The resistance of

potentiometers R8 and R28 for a particular board

must increase if the voltage across C6 is higher than

that of the opposite board or decrease if the voltage

across C6 is lower than that of the opposite board.

The amount of potentiometer adjustment required

will vary. Equally increase or decrease the resistance

of both (R8 and R28) by only 1 ohm if the voltage

imbalance is less than 30V. Increase or decrease

resistance of both potentiometers (R8 and R28) by 2

ohms if the voltage imbalance is greater than 30V.

R8 and R28 must be adjusted to the same resis-

tance.

12. After making these adjustments to the potentiom-

eters, repeat steps 10 to check the balance again.

Several adjustments might have to be made before

the voltage imbalance is less than 15V. As the im-

balance approaches 15V, smaller adjustments of less

than 1 ohm should be made on the potentiometers.

Always raise the potentiometer resistance of the

board with the higher voltage and lower the potenti-

ometer resistance of the board with the lower volt-

age.

Fig.4 - Placement of Voltmeter Leads

Fig. 3 - Location of Potentiometers & Drains

ESAB SVI-450i/DP - 450i Power Board Balancing Troubleshooting instruction

Brand: ESAB

Model: SVI-450i/DP - 450i Power Board Balancing

Category: Power adapters & inverters

Type: Troubleshooting instruction

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ESAB SVI-450i/DP - 450i Power Board Balancing Troubleshooting instruction

ESAB SVI-450i/DP - 450i Power Board Balancing Troubleshooting instruction

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