Thermal Dynamics MERLIN 6000 Service Manual page 47

Pilot Resistor
Clamp
R22
Wire
#96A
Pilot Resistor
R21
Temp
Switch
Wire
#150
Figure 4-4 Location Of Pilot Resistors (Viewed
From The Front Of Power Supply)
3. Check the busbar configuration on the input ter-
minal board to determine which range the power
transformer is set for.
4. Measure the level of the AC line voltage being sup-
plied to the Power Supply.
5. To determine the recommended pilot resistor set-
ting use the following table as follows:
a. Locate the transformer voltage range (200-230V,
380-460V or 500-575V)
b. Find the voltage that is nearest what was mea-
sured above.
c. Note the ohms value for the voltage. Example:
If the transformer range is 380-460, and the
measured voltage is 455, then the pilot resistor
value is 6 ohms.
NOTE
Voltages that are from 200 to 210V, 410 to 420V
and 510 to 520V required values from 8.5 or 9 to
4.5 ohms. If the voltage is near one of these points
it is best to set for the lower ohms value.
The reason is because within each range the Power
Supply will automatically select a high or low tap
on the transformer secondary. This is based on
the input AC line voltage at the time the Power
Supply is turned ON. If the line voltage is near
one of these points the voltage might measure, for
Manual 0-2569
Wire #99
Pilot Resistor
R16
Clamp
Wire
#96
Wire
#74
A-01853
example, 410 VAC and the pilot resistor setting
should be 9 ohms to have a good pilot. The next
time the system is turned ON, the input AC line
voltage may have gone up to 420VAC causing the
pilot to sputter because 420VAC requires setting
of 4.5 ohms.
Pilot Resistor Setting vs. Input Line Voltage
Transformer Voltage Range
200-230 VAC 380-460 VAC
Input Input
Ohms
(VAC) (VAC)
180 6.5 340
190 7.5 350
200 8.5 360
210 4.5 370
220 5.5 380
230 6.5 390
240 7.5 400
250 9 410
420
430
440
450
460
470
480
490
500
510
6. Wires are attached to the pilot resistors with metal
clamps or taps. Locate and loosen the screw that
secures the wire #99 tap on resistor R16. Deter-
mine, from the Figure below, the correct position
for the tap on R16 and tighten the screw.
Example:
To set for 6 ohms measure 5" from the right side
of R16, where wire # 96 attaches, and secure the
#99 tap at that position.
41
500-575 VAC
Input
Ohms Ohms
(VAC)
5 450
5.5 460
6 470
6.75 480
7.25 490
8 500
8.5 510
9 520
4.5 530
5 540
5.5 550
6 560
6.5 570
7 580 7.25
7.5 590
8 600
8.5 610 8.25
9 620
630
SERVICE TROUBLESHOOTING
5.5
6
6.5
7
7.5
8
8.5
4.5
5
5.5
6
6.5
7
7.5
8
8.5
9