Required Items
1 ea.--16 ohm 300W Resistor PN-17300016
2 ea.--Resistor Brackets PN-99512558
2 ea.--1/4” Mounting Screws PN-6125900
1 ea.--Bridge Diode PN-13730469
1 ea.--.02 mf Capacitor PN-674216
1 ea.--1” Mounting Screws PN-61325886
2 ea.--Flat Washers PN-64304880
1 ea.--Hex Nut PN-63300886
Change R44 Main PCB 60 hz. (38055) to 20 ohm.
16 ga. wire, connectors and tie wraps
Installation Procedure
1. Be sure
ALL power is disconnected from the
power source before removing any sheet
metal.
2. Remove the top and left side power source
sheet metal.
3. Assemble the circuit using the above sche-
matic as a reference. Be careful to measure
the correct wire length based on the recom-
mended placement of components.
4. Mount 16 ohm (300 W) resistor on opposite
side of lifting bail using the “L” brackets and
1/4” mounting screws as shown.
5. Route the wires of bridge diode along the
inside of the “A” frame and mount the bridge
diode to the front side of the “A” frame post
using the 1” long screw, washer, and hex nut
as shown.
Installation Instructions for
Heliarc 252 & 352
Low Current Kit
0558007408 03 / 2007
6. Attach the lugged end of the wire (resistor
side of the circuit) to the cathode side of
the SCR bridge as shown. Locate hex nut
and stud holding the copper bus to the
heat sink and place the wire ring lug under
the hex nut on the stud and secure.
7. Attach the lugged end of the wire (diode
side of the circuit) to the anode side of the
SCR bridge as shown. Locate hex nut and
stud above snubber PC board and place
the ring lug on the stud under the Hex nut
and secure.
8. Remove the screws in the upper corners
of the power source front control panel.
Pull the panel forward to expose the main
control board. Replace the R44 resistor
with a 20k ohm resistor.
9. Tie wrap and secure routed wires to exist-
ing wire harnesses or frame members.
10. Replace and secure all sheet metal sides
and hardware.
Notes on Heliarc 252 & 352 Low Current Operation
This low current circuit enhances the arc stability when welding at currents down to approx. 4 amps
for DC and 8 amps with AC. The circuit minimizes arc wander around the tungsten point that can
occur with low current operation. This modication also increases the usable arc lengths during
welding. The high frequency can be set to the “start only” or “continuous” position depending on
application and customer preference. Be sure to set the arc force to minimum and the balance
control Max. penetration for best AC performance and Max. Cleaning for best DC performance.
Arc starting at minimum currents (4 amps) requires a very short tungsten to work distance (<.040”).
Use the recommended tungsten size for the desired current for best arc starting characteristics. At
4 amps a .040” tungsten is recommended but good arc starts can be achieved using a 3/32” tung-
sten. Arc starting consistency with larger diameter tungsten is dependent on electrode pointing
techniques, grounding and base material surface condition.
When welding below a 6 amps preset current, use the HF “continuous” position to minimize arc
outages and allow more tolerance to changes in tungsten to work distance.
0558007408 03 / 2007
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