Power Supply Related Problems - Welch Allyn Grason-Stadler GSI 17 Series Service Manual

data lines.
In this instance probe these lines with an
oscilloscope and look for any address or data lines that are in-
active (no data or periodic state transition).
line is found the processor may be at fault but the problem is
most likely a bad port or latch somewhere on the bus.
of hardware failure generally requires replacement of the
Audiometer Board, as this is probably the most cost effective way
to resolve this type of problem.
A lock-up may also occur as the result of a defective EPROM
This EPROM contains all the instructions for the
(U505).
processor to execute.
may pause or get "LOST".
as these EPROMS are very stable devices.
When a new processor is installed into the audiometer board it
may lock-up. There are internal system configuration registers
that must be loaded by shorting JP1 pins 1 and 2 (Mode B pin 2 of
the processor to ground) prior to power-up.
for a period of (2 or 3 seconds) then power the unit down and
remove the jumper.
default data and perform self calibration (refer to Section 4,
Calibration).
also occur if a data error was present in the EEPROM portion of
the processor.

6.7 POWER SUPPLY RELATED PROBLEMS

The GSI 17 is powered by battery or by the Power Module (Battery
Eliminator/AC Adapter).
defective, first check the power source.
replaced? Were the batteries new?
eliminator functioning properly?
connector which attaches to the GSI 17?
have been answered then proceed with troubleshooting on the
Audiometer Board.
the positive terminal of C101 (use TP100 for ground reference).
Check the positive terminal of C100 for +5 Vdc.
negative terminal of Cl03 for -5 Vdc.
NOTE:
If any power supply voltage is incorrect the problem may
be the result of a short or load somewhere on the line.
It is best to try lifting the regulator output pin
the lifted pin prior to replacing the device.
output is correct with the pin lifted, check
capacitors for low impedance or a shorted device.
If the operating life of the batteries appears diminished,the low
battery indicator may be improperly calibrated or the GSI 17 is
drawing excessive current.
the battery calibration procedure.
If there are no instructions the processor
This type of failure very seldom occurs
The operator/technician should then load
It is important to note that this problem could
When a power supply is suspected to be
Check for the presence of 7 Vdc to 13 Vdc at
Refer to
If an in-active
After power-up wait
Have the batteries been
Dated?
Is there 13 V present at the
When these questions
If the
the power
Section 4, Calibration, for
This type
Is the power
Check the
and
measure
regulator
supply