Filament

FILAMENT

Inspection and Repair


INSPECTION






1.When measuring voltage, wrap tin foil around the top of the negative probe. Then press the foil against the wire with finger.





2.Attach probe circuit tester (in Volt range) to middle portion of each filament.





3.If a filament is burned out, circuit tester registers 0 or battery voltage.
4.To locate burned out point, move probe to left and right along filament. Test needle will swing abruptly when probe passes the point.

REPAIR

REPAIR EQUIPMENT
- Conductive silver composition (DuPont No. 4817 or equivalent)
- Ruler 30 cm (11.8 in) long
- Drawing pen
- Heat gun
- Alcohol
- Cloth
REPAIRING PROCEDURE





1.Wipe broken heat wire and its surrounding area clean with a stop cloth dampened in alcohol.
2.Shake silver composition container before use.
Apply a small amount of conductive silver composition to tip of drawing pen.
3.Place ruler on glass along broken line. Deposit conductive silver composition on break with drawing pen. Slightly overlap existing heat wire on both sides [preferably 5 mm (0.20 in)] of the break.





4.After repair is completed, check repaired wire for continuity. This check must be conducted 10 minutes after silver composition is deposited.
Do not touch repairing area while test is being conducted.





5.Apply a constant stream of hot air directly to the repaired area for approximately 20 minutes with a heat gun. The minimum distance of 3 cm (1.2 in) must be kept between repaired area and hot air outlet.
If a heat gun is not available, let the repaired area dry for 24
hours.