Thermal Dynamics MERLIN 6000 Service Manual page 36

four different plasma gases. The outlet of the
Plasma Select Manifold is connected by a hose to
the Plasma Gas Control Solenoid SOL1.
b. A voltage of 120 VAC is output from the Power
Supply Logic PC Board at J2-3, Plasma Relay (K4).
The voltage is routed through the Power Supply
to J51-1, then to the Gas Control Connector, J63-1.
The voltage then is sent out to the Gas Control
(GC3000) Plasma Gas Select Switch SW1. Switch
SW1 sends the 120 VAC back to one of the plasma
select solenoids at the Merlin 6000 Rear Panel.
c. To check for operation of the Gas Select Manifold,
loosen, but don't remove, the hose going to the
Plasma Gas Solenoid SOL1.
• If gas is escaping, the manifold is working and
the problem is with the Plasma Gas SOL1 gas
control circuit. Troubleshoot using the same
procedure as in Plasma Gas Problems With-
out Optional Gas Control above.
• If no gas leaks from the loosened hose then the
problem is with the Gas Select Manifold. Pro-
ceed to next step.
d. Try selecting a different plasma gas. If using only
using one plasma gas, move it to a different gas
inlet. If plasma gas flows, then the original sole-
noid is most likely faulty.
e. Measure the resistance of the solenoid coil for ap-
proximately 300 ohms.
• If the resistance is incorrect replace the mani-
fold.
• If the solenoid coil resistance is correct proceed
to next step.
f. Measure for 120 VAC across the solenoid coil.
• If the voltage is present and the solenoid is in-
operative then the solenoid is faulty.
• If there is no voltage at the solenoid use the Gas
Control Wiring Diagram to determine where
the voltage is being lost.
• Secondary Gas Problems With Optional Gas
Control (GC3000)
NOTE
For detailed of circuits refer to Appendix XXII, Gas
Control Wiring Diagram.
a. The Optional Gas Control (GC3000) uses the origi-
nal Secondary Gas Control (SOL2) to both select
and control Secondary Air. It also uses the origi-
nal Secondary H 0 Control (SOL3) to both select
2
and control secondary water. In addition, two new
SERVICE TROUBLESHOOTING
solenoids, SOL8 & SOL9 are added to the Merlin
6000 Power Supply Rear Panel to select and con-
trol nitrogen (N2) and 'Other' secondary gases.
'Other' may be any gas the user wishes to use.
b. The original Secondary Gas Select Switch, SW3, on
the Merlin 6000 Front Panel is always set to the
GAS position and the Secondary Gas Select Switch,
SW2, on the GC3000 front Panel is used instead.
c. In the Power Supply 120 VAC from the Logic PC
Board Secondary Relay (K3) from J2-7 is routed
through SW3 (set to GAS) and out through J51-2
and the Gas Control Connector J63-10 to the
GC3000 Secondary Select Switch, SW2.
d. If there is no secondary flow or pressure, try se-
lecting a different gas (if only using one gas, move
it to a different inlet). If gas flows then the origi-
nal solenoid is most likely faulty.
e. Measure the solenoid coil resistance for approxi-
mately 300 ohms.
• If the resistance is incorrect the solenoid is faulty.
• If the resistance is correct proceed to the next
step.
f. Measure for 120 VAC across the solenoid coil (set
SW2 to select that solenoid).
• If the 120 VAC is present and the solenoid is
inoperative, it is faulty.
• If there is no voltage at the solenoid use the Gas
Control Wiring Diagram to determine where
the voltage is being lost.
I. Coolant Flow Sensor Circuit Check
The Flow Sensor (FS1), for the coolant, contains a switch
that is calibrated for 0.25 gpm (1.1 lpm). When the cool-
ant flow rate equals the calibrated rate of FS1 it will close.
Use the following procedure for a quick check to test the
operation of the Flow Sensor (FS1):
1. Disconnect connector J25.
2. Jumper across the two sockets.
3. Check the COOLANT PRESS LED for ON condi-
tion.
• If LED comes ON, then the Flow Sensor (FS1) is
faulty, except if there is low coolant flow.
• If LED is OFF make the following checks:
Measure voltage between J1-5 and J1-4 or TP1. If
J1-5 is greater than 1 volt, FS1 or connections to
FS1 are faulty. If J1-5 measures close to 0 vdc, check
J3-2. If J3-2 measures less than +12 vdc, and the
30 Manual 0-2569