Tweco 400 Ultra-Cut(May 2014) - Manual (Page 188)

ULTRA-CUT 100 XT/200 XT/300 XT/400 XT
A-60 APPENDIX Manual 0-5302
Troubleshooting:
1. Determine if the problem is a lack of HF (Arc Starter) or if it’s due to the pilot circuit.
Auto-cut XT Arc Starter (inside main chassis for AC200 XT; in the GCM1000XT for AC300XT) has open spark gap. If the spark
gap is firing it is receiving power. A few early Ultra-Cut XT units were shipped with the RAS1000 Arc Starter. Troubleshoot
them the same as the GCM1000XT below. Most Ultra-Cut XT units now use the RAS1000XT Arc Starter which doesn’t use
a spark gap and is covered in the next section.
Arc starter with Spark Gap (Auto-Cut)
No spark at spark gap
1. Check that spark gap is set for 0.062” +/- 0.002”. If gap is too high there may not be enough voltage from T1 to fire the
gap.
2. Check for power to the high frequency (HF) transformer (T2 in AC 200 XT; T1 in GCM1000XT) during the 15 seconds
following prefow (ignition phase). Arc starter power comes through the rear panel circuit breaker CB4, make sure it isn’t
tripped.
a. For the GCM1000XT (AC300XT) 120 VAC from J59-7 & 9 on the power supply rear panel connects to J58-7 & 9 on
the GCM 1000XT. See diagram below. From J58 on the GCM1000XT it goes directly to the line filter and passes
through the filter to primary of T1. During the ignition phase, check for 120 VAC on the T1 side of the line filter.
b. For AC200XT the HF transformer T2 has insulated Faston (also known as push on , stab-on, spade, etc.) on its primary
wires. Disconnect these and measure for 120 VAC on the harness side during ignition phase.
3. If 120 VAC not present go to step 4.
a. If 120 VAC is present and still no spark, T1 (T2 in AC200XT) may be bad. Remove power and measure resistance of
T1 (T2 in AC200XT) primary and secondary. The primary should measure about 3-7 ohms. The secondary about
25-35 K ohms. If either measurement not correct replace T1 (T2 in AC200XT).
b. If T1 (T2 in AC200XT) measures OK, check for shorted capacitors C1-C3 (very unlikely).
4. No 120 VAC to T1 (T2 in AC200XT) primary during the ignition phase (15 seconds following Preflow) check for 120 VAC
into the line filter (GCM1000XT only). If it’s there replace the filter. If 120 VAC isn’t present at the line filter or if this is
an AC 200XT go to step 5 in section Either Arc Starter below.
Arc starter without Spark Gap (Ultra-Cut)
1. Check for power to the RAS 1000XT’s Ignition Module during the 15 seconds following preflow (ignition phase). Arc
starter power comes through the rear panel circuit breaker CB4, make sure it isn’t tripped.
a. During the ignition phase, measure for 120 VAC at the input terminals marked 120 VAC on the Ignition module, a gray
rectangular box with screw terminals on one side.
WARNING!
Do not let the meter probes (or your hands) come in contact with the other terminals marked Hb and Ho or the other
end of the wires connected to them. These can have 10,000 volt pulses which can cause physical harm and will
damage your meter.
2. If 120 VAC is not present go to step 3.
a. If 120 VAC is present and still no spark, the Ignition Module may be bad.
3. 120 VAC to the remote Arc Starter comes from J59-7 & 9 on the power supply rear panel and connects to J58-7 & 9 on
the RAS1000XT. Remove the cable from J59 and during the ignition phase measure for 120 VAC between pins 7 & 9.
a. If 120 VAC is present problem is in the cable to the RAS 1000 XT or the J58 connector and internal harness in the
Arc Starter.
b. If 120 VAC is present proceed to the next step.