(2)  
Equipment and Materials

(a)  Ohmmeter, zero to 500 ohm range, accurate to + 5 percent

(3)  
Test Window Resistance

(a)  
Open respective WINDOW ANTI-ICE circuit breaker on circuit breaker panels P6-11 or P6-12.

(b)  
Disconnect electrical leads from window No. 1 and 2 bus bar terminals and measure bus to bus resistance of window by connecting ohmmeter across window terminals.

(c)  
Check that window resistance is within limits and electrical leads are connected to correct control unit output terminals as shown in figure 501.

(d)  
Disconnect ohmmeter, reconnect all window leads and close window anti-ice circuit breakers opened in step (2) (a).

500 
May 15/67  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  30-41-21 Page 501 

C.  Windows No. 1 and 2 Heat Sensor Resistance Test
(1)  
Equipment and Materials

(a)  Ohmmeter, zero to 500 ohm range, accurate to ± 5 percent

(2)  
Test Window Heat Sensor

(a)  
Open respective WINDOW HEAT CONTROL circuit breakers on circuit breaker panel P18-3.

(b)  
Disconnect electrical leads from window heat sensor terminals and measure resistance of sensor by connecting ohmmeter across sensor terminals.

(c)  
Check that resistance is within limits shown on figure 502.

Window Resistance and Control Unit Output Terminal Table  509 
30-41-21  Figure 501  May 01/74 
Page 502 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

NOTE:  Sensing elements which have become open circuited during flight while airplane is pressurized will commonly exhibit continuity when tested with airplane depressurized. If a sensor is suspected of intermittent operation, apply the following test for intermittent sensor operation.

500  Window Heat Control Sensor Resistance 
May 15/67  Figure 502 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  30-41-21 Page 503 

1)  Test for intermittent sensor operation.
CAUTION:  DO NOT APPLY CHECK FOR INTERMITTENT SENSOR OPERATION IF WINDOW IS IN A COLD SOAKED CONDITION AS CONTACT WITH HOT PLATE COULD CAUSE DAMAGE TO WINDOW.
a)  Heat a piece of aluminum plate, approximately 1/4 to 3/8 inch thick by 3 inches square, to 200 + 10°F by placing in boiling water and place against outer pane of window directly over window heat sensing element.
b)  Select as high a scale multiplier on ohmmeter as practical to observe increase in sensor resistance. If resistance increases to infinity, sensor is defective.
NOTE:  If too high a scale multiplier is selected, a resistance between 1000 ohms to infinity may be noted; however, this would still indicate a defective sensor.
(d)  Disconnect ohmmeter, reconnect window heat sensor terminals and close window anti-ice circuit breakers opened in step (2)(a).
D.  Windows No. 4 and 5 Conductive Coating Resistance Test
(1)  
Equipment and Materials

(a)  Ohmmeter - 0- to 500-ohm range, accurate to + 5 %

(2)  
Test Window Resistance

(a)  
Open respective WINDOW ANTI-ICE No. 4 and 5 circuit breakers on panel P6-11 or P6-12.

(b)  
Disconnect electrical leads from window No. 4 and 5 bus bar terminals and measure bus to bus resistance by connecting ohmmeter across window terminals.

(c)  
Check that resistance is within the following limits. 1) Window No. 4, PPG: between 61.6 and 83.4 ohms Triplex: between 41.3 and

55.8 ohms 2) Window No. 5, PPG: between 40.6 and 55.0 ohms Triplex: between 34.1 and
46.0 ohms

(d)  
Disconnect ohmmeter, reconnect all window leads and close window anti-ice circuit breakers opened in step (2)(a).

500 
30-41-21 Page 504  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  Jun 20/92 

WINDOW NO. 3 AND 5 THERMAL SWITCH - REMOVAL/INSTALLATION
1.  General
A.  A window heat thermal switch is installed near the bottom of the No. 5 window on each side of the control cabin. The window has an arrow and the words LOCATE SWITCH etched on the inner pane parallel to the lower bus bar to indicate the preferred area for thermal switch location. Each thermal switch is held against its window by a rat-trap type spring (Fig. 401).
B.  A conductive cement compound is applied between the contacting surfaces of the switch and the pane, the curvature of which would otherwise impair transfer of heat to the switch.
　
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