ESAB SCR Control P.C. Board Retrofit Kit Troubleshooting instruction

Brand: ESAB

Model: SCR Control P.C. Board Retrofit Kit

Type: Troubleshooting instruction

INSTRUCTIONS for

F-15-002-A

May, 1995

This retrofit kit contains a modified SCR control p.c.

board, P/N 31545, which is provided as an equivalent

replacement for older-style SCR control boards, P/N

675405 w/integral CCP pot, used in Heliarc 250 HF/pf

units.

The retrofit kit’s p.c. board has been redesigned to pro-

vide more secure and reliable wiring termination at the

board (using plug connectors), and to improve low out-

put stability in low ampere applications.

The retrofit kit, P/N 31236 consists of the following:

Qty. P/N Description

1 31454 SCR Control P.C. Board Assy.

1 31066 P1, 6-Pin Plug/Lead Assy.

1 31067 P6, 5-Pin Plug/Lead Assy.

1 953916 CCP Pot, Front-Panel Decal

1 31065 CCP Pot

To install the kits SCR control Board do the following:

Electric shock can kill. Precautionary measures

should be taken to provide maximum protection

against electrical shock. Be sure that all primary

power to the machine has been externally discon-

nected. Open wall disconnect switch or circuit

breaker before attempting inspection or work inside

the power supply.

1. Remove the top and side panels of the power supply

to gain access to the internal components.

2. Unpack SCR control board and inspect the setting of

the SW2 “dip” switches located on the lower left-hand

side of the p.c. board as shown in Figure 1. Depend-

ing on the “vintage (age)” of the power supply being

repaired, make sure the SW2 “dip” switches are set

(or repositioned) as follows.

a. All 250’s manufactured “after” serial number

B87B72400 incorporating an Arc Force control

feature on the front panel, the SW2 dip switches

must be set (or repositioned) to the OFF or OPEN

position.

b. All 250’s manufactured “prior” to serial num-

ber B87B72400 “do not” contain the Arc Force

control and SW2 dip switches must be set (or re-

positioned) to the ON or CLOSED position.

NOTE: Some “dip” switches may be marked with “O”

or “I” to identify the OFF and ON modes re-

spectively.

3. Before physically removing the old SCR Control

board, it is suggested that the two plug/lead assem-

blies (P1 and P6 provided in the kit) be connected to

the existing wire terminations, of the old SCR board,

as shown in Figure 2.

Fig. 1- SCR Control Board # 31545

(Part of Retrofit Kit P/N 31236)

SCR CONTROL P.C. BOARD RETROFIT KIT

P/N 31236

Be sure this information reaches the operator.

You can get extra copies through your supplier.

Fig 2 - Heliarc 250 HF/HFpf SCR Control P.C. Board Retrofit Wiring

You may also notice that an additional wire (orange)

attached to the kit’s P6 plug (at terminal B) will need

to be connected in your machine because of the modi-

fied circuitry on the new p.c. board. This is also clearly

shown on the appropriate diagrams in Fig. 2.

After all of the new plug/lead reconnections have been

properly made, you can install the new p.c. board and

insert the P1 and P6 plugs into the board receptacle

headers.

Tape any exposed connections in the new plug/leads

(to prevent any possible short circuiting), and secure

all loose wires to the existing wire harness(es).

4. Please not that the kit also contains a new current

control (CCP) decal. Place it directly over the exist-

ing silk-screen markings for this potentiometer on the

front panel.

5. This completed the retrofit installation and you can

replace the covers and test the unit.

F-15-002-A 5/95 1C Printed in U.S.A.

ESAB SCR Control P.C. Board Retrofit Kit Troubleshooting instruction

ESAB SCR Control P.C. Board Retrofit Kit Troubleshooting instruction

ESAB SCR Control P.C. Board Retrofit Kit Troubleshooting instruction

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