TM 9-4910-663-34
(6)
Connect the ohmmeter between terminal 8 of the PC board assembly and the center terminal of
potentiometer R20. The resistance should be adjustable from zero to 250 ohms ±10% by adjusting the potentiometer.
Replace potentiometer R20 if the correct indication is not obtained.
(7)
Connect the ohmmeter between terminal 5 of the PC board assembly and the center terminal of
potentiometer R21. The resistance should be 8660 ohms ±1%. Replace resistor R23 if the correct indication is not
obtained.
(8)
Connect the ohmmeter between terminal 9 of the PC board assembly and the center terminal of
potentiometer R21. The resistance should be adjustable from zero to 500 ohms ±10% by adjusting potentiometer R21.
Replace potentiometer R21 if the correct indication is not obtained.
(9)
Connect the ohmmeter between terminals 6 and 12 of the PC board assembly. The resistance should be
10,000 ohms ±1%. Replace resistor R8 if the correct indication is not obtained.
(10)
Connect the ohmmeter between terminals 11 and 12 of the PC board assembly. The resistance should be
40,200 ohms ±1%. Replace resistor R9 if the correct indication is not obtained.
(11)
Connect the positive lead of the ohmmeter to terminal 5 of the PC board assembly, and the negative lead
of the ohmmeter to terminal 10. If the ohmmeter reading is less than 5 ohms, replace diodes CR13 and CR11. If a very
high resistance reading is obtained, replace diode CR11. If a reading between 5 and 20 ohms is obtained, reverse the
ohmmeter leads; if a high resistance reading results, replace diode CR13.
c.
Removal and Replacement of PC Board Assembly Parts. Instructions for removal of the PC Board Assembly
from the test stand are provided in para 2-13.
(1)
Using a low wattage soldering iron, unsolder the leads of the defective part from the printed circuit board,
and remove the part.
CAUTION
Do not overheat the printed circuit board; otherwise the PC board copper clad may lift off.
(2)
Clean the area of excess solder, using a de-soldering bulb.
(3)
Insert the leads of the replacement part through the holes in the printed circuit board.
(4)
Solder the replacement part leads to the printed circuit board.
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