For leakage from the signal relay, use the following procedures. Refer
to figure 5-5.
(a) Test for improper seating of the diaphragm with a soap solution. If
the leakage is from the exhaust holes on the sides of the signal relay, proceed with (b).
If the leakage is at the diaphragm line, tighten the signal relay mounting screws. If the
leakage persists, replace the diaphragm.
(b) Test to see if the signal relay inlet seal does not fully close. Shut
the unit OFF. Remove the signal relay from the foot control, inspect the stem, O-rings,
and seats for debris or defects. If you see no defects, carefully clean and lubricate the
parts, reassemble, and test the valve. If the test is abnormal, replace any defective
parts. Clean and lubricate the parts, reassemble, and test the valve.
(4) If the air is leaking around a barb connection, tighten the barb and re-
test the valve.
(5) If the air is leaking from the exhaust vent or around the bottom of the
valve body, proceed with the next step.
c. Determine if there is a defective O-ring or sealing surface, poppet or inlet
Turn the unit to OFF and bleed the air pressure.
Disassemble the foot control.
Inspect the O-rings and sealing surfaces for defects or debris.
(4) If you have leakage from the exhaust vent, inspect the poppet and inlet
seal for defects or debris.
(5) If no defects are noted, carefully clean and lubricate the parts.
Reassemble and test the valve.
(6) If the test is abnormal, replace any defective parts. Carefully clean and
lubricate the parts. Reassemble and test the valve.
TROUBLESHOOT A HANDPIECE HOLDBACK SYSTEM MALFUNCTION
Sometimes the handpieces on the dental operating unit will continue to run while
in their holders. You isolate the malfunction based on how the holdback system is
malfunctioning. Refer to figure 5-6.