Welch Allyn Grason-Stadler GSI 17 1717-9700, Service Manual

Page: 56 / 104

6.2 OUTPUT RELATED TROUBLESHOOTING SYMPTOMS
Symptom
Output failures
Possible Solution(s)
Earphone Cord, Earphone, Patch
Cord/Jack Panel If applicable,
Amplifier, Output Routing, Amp
Enable/Disable, L/R Switch, Amp
Latch/Control Circuit.
GENERAL APPROACH TO FAULT ISOLATION
If the loss of output is isolated to only one of
the
then
earphones
try
exchanging the earphone assemblies.
Plug the left
earphone into the right earphone jack and the right earphone into
the left earphone jack. If the problem shifts to
the
earphone, then the problem is internal to the Audiometer.
opposite
If the
problem remains with the original earphone, then
the
assembly is at fault.
earphone
If the earphone assembly is found to be
defective, first check the set screws and assure that
they are
tightened securely. If the screws are loose a problem similar to
this would result. If the screws are secure try exchanging
the
left and right earphone cords, assure that the earphone serial
numbers are legible, if not mark the earphones accordingly.
The
earphones are calibrated specifically to the left and right
amplifiers. If the problem shifts to the opposite earphone
then
the phone cord is defective. If the problem remains with
original earphone then the earphone is defective.
CIRCUIT ANALYSIS FAULT ISOLATION
Refer to Audiometer Board Schematic
#3,
Section 8.
AT-I-EN
the
Figure 6-2: BLOCK DIAGRAM OF AMPLIFIER SIGNAL FLOW