Hypertherm Powermax125 Service Manua - Manual (Page 213)

Powermax125 Service Manual 808070 213
9 – Power Supply Component Replacement
Replacing the snubber resistor
1. Complete the following procedures:
a. See Disconnect the power and gas supply on page 166.
b. See Remove the power supply cover on page 172.
c. See Remove the component barrier on page 173.
d. See Remove the DSP board on page 203.
e. See Remove the power board on page 205.
2. Remove the 2 mounting screws from the appropriate snubber resistor. See Figure 76 on page 215.
3. Remove the snubber resistor from the heatsink.
4. Clean the area where the snubber resistor was mounted using isopropyl alcohol to remove the old thermal grease
from the heatsink.
5. Apply a 0.0762 mm (0.003 inch) layer of thermal grease, about the thickness of a sheet of paper, evenly to the
snubber resistor mounting surface.
6. Mount the snubber resistor to the heatsink as follows by hand-tightening the 2 supplied mounting screws. (See
Figure 76 on page 215.)
 Kit 428137 – Align the snubber resistor so the 2 threaded studs are on the bottom of the snubber resistor.
 Kit 228898 – Align the snubber resistor so the 2 threaded studs are on the left side of the snubber resistor.
7. Step-torque the 2 mounting screws to the proper torque value as shown in Figure 76 on page 215.
8. Tighten the 2 supplied standoffs in the threaded holes of the snubber resistor to 11.5 kg-cm (10 inch-pounds). Verify
the standoffs are firmly seated to the resistor for a solid electrical connection.
9. Complete the following procedures:
a. See Install the power board on page 206.
b. See Install the DSP board on page 203.
c. See Install the component barrier on page 173.
d. See Install the power supply cover on page 172.
e. Reconnect the power and gas supply.
Kit number Description
428137 Kit: Powermax125 snubber resistor 7.5 Ω with thermal grease
228898 Kit: Powermax105/125 snubber resistor 15 Ω with thermal grease