Tweco PAK 10 - Manual (Page 32)

Service 20 Manual No. 0-0515
When the torch switch is pressed, the gas and red “DC
POWER” light should come on. If this does not hap-
pen, check as follows:
F. Gas does not flow when torch switch pressed
1. Torch switch not connected
a. Check wires to plug, switch, and receptacle.
2. Torch switch not closing
a. Check for continuity when pressed.
3. Faulty control relay 1CR
a. Check relay (See C, Test Procedures).
4. No 24 volt power
a. Check output of transformer T2 (See B, Test
Procedures).
G. No red “DC POWER” light
1. Pressure switch PS1 or PS2 not satisfied
a. Check and adjust gas pressure regulator
Plasma should be 30 psi (2.0 bar), secondary
should be 50 psi (3.4 bar).
2. Faulty main contactor (W)
a. Check contactor (See D, Test Procedures).
3. Failed diodes in main rectifier
a. Check diodes (see E, Test Procedures).
The Pilot Arc should start two seconds after the red
“DC Power” light comes on. If it does not, check the
torch parts to make sure they are in good condition and
properly assembled. Check to see if:
1. PCR relay energizes at the time the pilot arc should
start (two seconds after pressing switch).
2. There is any reading of the ammeter (normal Pilot
Arc is 8 to 12 amps).
3. There is any light visible inside the torch.
H. No PCR movement two seconds after torch
switch pressed
1. Faulty time delay TD2
a. Check TD2 (See A, Test Procedures).
I. No pilot but ammeter reads 40 amps
1. Torch assembled without gas distributor
a. Assemble torch with correct parts (See Sec-
tion 4.1.)
2. Shorted torch head
a. Replace.
3. Shorted torch leads
a. Repair or Replace.
J. No spark can be seen in torch
1. High frequency points shorted
a. Clean and dry area around high frequency
points, adjust gap to 0.015".
2. Shorted capacitor C-1
a. Check (See F, Test Procedures).
3. CSR closing with no cut
a. Check for shorted toroid (See G, Test Proce-
dures). Replace CSR.
4. Broken conductor in torch leads
a. Repair or replace.
5. High frequency transformer T3 failed
a. Check (See H, Test Procedures).
6. Dirty or wet torch leads
a. Clean and dry leads.
K. Spark in torch but no pilot (ammeter reads 0)
1. Insufficient DC voltage
a. Check for 205 volts open circuit (See J, Test
Procedures).
2. Pilot contactor (PCR) not closing
a. Check for DC at torch (See L, Test Proce-
dures).
3. Pilot resistor failed
a. Check resistor (See K, Test Procedures).
The Cutting Arc should start as soon as the torch, with
the pilot arc running, is brought to within about 3/8
inch (10 mm) of the workpiece. If it does not, check:
L. No cutting arc
1. Work cable not connected
a. Connect.
2. One leg of 3-phase primary out
a. Check all 3 input phases for voltage.
3. One leg of main contactor (W) not closing
a. Check voltage at diodes (See M, Test Proce-
dures).