Johnson & Associates GSM-500 Manual
illo
DilLg$ill'5oo
SURVEY
METER
OPERATIONS
& MAINTENANCE
SECTION
I
2
3
4
3
6
7
8
PO
Box472
Ronceverte,
WestVirginia 24970
Telephone:
304-645-6568
200AEI Drive
Lewisburg,WestVirginia 24901
Fax:
304-645-21E2
MANUAL
CONTENTS
SPECIFICATIONS
DESCRIPTION
THEORY OF OPERATION
OPERATING
CONTROLS
OPERATING
INSTRUCTIONS
MAINTENANCE
PARTS
LIST
CHECK SOURCE
INSTALLATION
Wm B. Johnson & Associates
Inc.
Email:
buyjohnson(@msn.com
WMBJ
----r--
GSM.5OO
EXTERNAL PROBE
LINEARIZATION
EXTERNAL PROBE
RANGES
INTERNAL
DETECTOR
RANGES
INTERNAL DETECTOR IS ENERGY COMPENSATED 50 KeV TO 2NteV +20o/o
1.0
SPECIFICATIONS
INPUT
SENSITIVITY
RANGE
ADJUSTMENT
ELECTRICAL
LINEARITY -.--------.--
RADIATION DOSE LINEARITY
RESPONSE
TIME
DRIFT
TEMPERATURE
COEFFICIENT
HIGH VOLTAGE
HIGH VOLTAGE INTERNAL
DETECTOR
---
PROBE
SATURATTON
(OVERLOAD)
LOW VOLTAGE ------
BATTERY ---
0.050v-p-p
(external
probe)
5 POSITIONINTERNAL SWITCH
- RESPONSE
CURVES
FOR
UP
TO 7 PROBES
ARE
PRE-PROGRAMMEDAND ARE SWITCH
SELECTABLE
4
LTNEARRANGES
(NOTE)
0 - .2
mR/H
--- 0
- 2 mR/hr ------- 0 - 500CPM
0
- 2 mR/H -*- 0
- 20 mR/hr --- 0 - 5.000CPM
0
- 20 mR/H
----
0
- 200mR"/hr
-----
0
- 50,000CPM
0 - 200mRiH
---
0
- 2000mR./hr----0
- 500.000CPM
EACH RANGE HAS SEPARATE NON
INTERACTING CALIBRATION CONTROLS
4 LINEAR RANGES
0-2 mVhr
0
- 20 mR/hr
0
- 200mWhr
0
- 2000mR/hr
EACH RANGE
HASSEPARATE
NON
INTERACTING
CALTBRATIONCONTROLS
AUTO
RANGING
+
5% OF FULL SCALE
+ IOO/O
OF
FULL SCALE
OPTIMIZED FOR EACH RANGE
LESS
THAII 5%
LESSTHAN 0.2%/DEGREEC
ADJUSTABLE.3OO
- 15OOVDC
REGULATION+
I%
550vdc +20vdc
--REGULATION
+ 1%
AUTOMATICALLY LOCKS METER FULL
SCALX UNTIL RADIATION FIELD RETURNS
TO NORMAL OPERATING RANGE
+5
VDC & -5
VDC REGULATION t 0.5%
6 - IIAAII ALKALINE
coPYRtGHT@
2006
wM B.
JOHNSON
&
ASSOCIATES
1.0 SPECIFICATIONS
. CONTINUED
BATTERY OPERATION
METER ----
TEMPERATURE RANGE
HUMIDITY RANGE -----
2OOHRSNOMINAL
4.22''SCALE
- RUGGEDIZEDMETER
MOVEMENT CALIBRATED O
- 5OO.O
- .2
LINEARITY +
3%
-20oF
(-28o
C)
TO l20oF
(50.C)
5
-95Vo
NONCONDENSING
7
%"
(18.5
cm)L X 2 !/e"
(7
cml H X 4 5/8" (l l.75cm)DEEP
3
pouNDS (1.4k) TNCLUDTNG
BATTERTES
16Ga.
ALUMINUM WITH
HEAVY DUTY CARRYING
HANDLE
BLUE CATALYZED POLYURETHANE WASH
PRIMERUNDERCOAT
LATCHES THAT SECURETHE TOP AND
BOTTOM HOUSING ARE PROVIDED
WITH HOLESFOR TAMPER SEALS
DIMENSIONS ---
WEIGHT
HOUSING
HOUSING FINISH
CALIBRATION SECURITY
2.0
DESCRIPTION
The Model GSM-500 is
a ruggedized,
multi purpose
survey
meter that hasa internal energy compensatedGM detector
and a wide choice
ofexternal detectors.
Both internal and external detectors
are calibrated separately
using
the same
standard potentiometer type calibration controls. Both detectorscan
function asa regular RATEMETER or
INTEGRATING METER (DOSE AND CPM). The external
input is designed
to accepta wide variety of different
probes including GM and SCINTILLATION PROBES. The high voltage
for eachdetector
can be adjusted to a
different voltage
that is
automatically provided when the detector
is selected
for operation. Probesare constantly
monitored for saturation (overload). In the event
of Saturation meter
will be electrically locked full scaleuntil the
radiation field at the probe returns to the normal operating range.
The internal detector
can only be dosecalibrated
(Cst"). The external detector
can
be calibrated in doseand cpm.
The mode of operation (dose
or cpm) is
switch
selectable
from the front panel.
An automatic
timed integration feature that provides
severaladjustable preset
integration times
is available
for both detectors
asan option. The timed integration set
point can be viewed on the
panel
meter and easily
adjusted
by internal screwdriver adjustment.
Calibration of the GSM-500 is easybecause
the
high efficiency
MICROPROCESSOR circuitry and built-in linearization curvesthe probes
on the internal and
external
detectors
greatly improves the overall accuracy
ofthe model 500.CPM calibration is factory set and doesnot
require field adjustment.
Diagnosticcircuitry constantly
monitors the battery, high voltage
and detector
condition and
automatically indicator when operation
is
out of tolerance.
A heavy-duty
analog
meter
with a large 4.2" scaleand red
LED's display the 4 linear ranges,signal
and internal diagnostics
for easyviewing day or night. RESPONSE
time for
each
range is automatically optimized
for each
range.
A speaker
that produces
a loud AUDIBLE CLICK for each
probe pulse
can be turned OFF or ON from the front panel. Durability is enhancedby heavy duty' castaluminum
construction and the directinterconnection
ofthe industrial type printed circuit boards.
copyRrGHT@
2006WM
B.JOHNSON
& ASSOCIATES
WMBJ GSM.5OO
3.0THEORY OF OPERATION
3.1 GENERAL:
The GSM-500 utilizes
the latest
field proven,
microprocessor
circuitry and internal probe response
curvesto operate
an internal energy
compensatedGM detector and a variety of detector from the external input. The instrument can
function as
a regular ratemeter
without deadtime compensation,regular ratemeter
with dead
time compensationand
integrating meter. Range
changing is automatic for all ranges
and both internal and external inputs have separatenon
interacting controls for dosecalibration. Calibration of the counts/minute
scales
for both detectors
is AUTOMATIC
and not required in the field. Operation in either the counts/minute
or dose
modeis
switch selectable
from the front
panel. The electronic
circuitry is located
on 2 heavy
duty printed circuit boards and is
powered
by highly regulated
-5
vdc & +5 VDC (+ 0.5%) low temperature coefficient
power supplies. A separatehigh stability power supply
with a low
temperature coefficient
can be adjusted
to provide a different
operating voltage fioreachdetector
(300
- 1500vdc
(ll%). Diagnostic
circuitry constantlymonitors the power supply, high voltage
supply and GM detector
(saturation)
and indicates
out of tolerance
operation with RED LED's and by locking
the meter full scale
for saturation. An analog
meter
with a large 4.22" scale
indicates
the probe signal level
and operating range.The probes
are connectedto the
main electronics
housing
by a high quality coaxial cablewith quick disconnectBNC connectors.
3.2 DETECTOR SIGNAL - DIAGNOSTICS - CALIBRATION CONTROLS
A microprocessor
meter operatesmuch
differently than an analog
type meter.
Most of the functions i.e.
deadtime
correction,
diagnostics
etc.
are provided by the microprocessor
programming (software).
The GSM-500's
hasbeen
pre-
programmed with the response
curves
and deadtime correction for 6 different probes.
Switch SW4 is
the internal
PROBE SELECTION switch that must
be ADJUSTED TO THE CORRECT PROBE BEFORE CALIBRATION. The
position
of SW4 (0-5)
selects
the correct software
for the probe being utilized on the internal and external probe.
SW3
tellsthe microprocessor
which detector
is being calibrated and SW5 serves
severalfunctions i.e.acknowledgecal pots
have
beenset
correctly and to showalarm and timed count set
point on the panel
meter. In this system
the calibration
potimeters
Pl -P4 are utilized to calibrate both the #1 and
#2 input. The software
selectedfor eachdetector
(internal
and external) includes
the DEAD TIME CORRECTION for the CPM operating mode,the High Voltage setting for
the probe selected
and RESPONSE
LINEARIZATION for the probe in the DOSE mode.THE INSTRUMENT MUST
BE OPERATED IN THE *O'ZERO POSITION AFTER THE CALIBRATIONS HAVE BEEN COMPLETED. When
the calibration ofeach probe has
beencompleted
the operator only needs
to select
the desired
probe (internal or
external)
and all settings
and adjustmentsare automatically applied to the probe
selected.
The GSM-500 needs
only to
be
calibrated in the DOSE MODE (referenced
csl37)for probes
connected
to either input. The internal probe selection
switch must
be adjusted
to the calibration position
and correct probe position
and the range
potentiometers
P1-P4
AdJusted.
THIS PROCEDURE MUST BE COMPLETED FOR EACH INPUT FOR DOSE CALIBRATION ONLY.
NO CALIBRATION IS REQUIRED FOR ANY PROBE IN THE CpM MODE. THE GSM-500 IS
AUTOMATICALLY CALIBRATED IN THE CPM MODE BY THE MICROPROCESSOR. A list of the probes
and
corresponding
switch positions
are on a label in the bottom housing
and in section6.2.5
of this manual The digital
signal from the internal and external
probe is connected
to through connector
UW-100 and C12 to pin 2 of U6
depending
on the setting
of the MAIN SELECTOR SWITCH. The MAIN SELECTOR SWITCH selectsthe probe
INPUT SIGNAL internal or external. Figure I showsthe front panel
controls
of the GSM-500.
3.3
SIGNAL CONDITIONING
The INTERITIAL and EXTERNAL probe
signal
are routed to the main circuitry by the MAIN SELECTOR SWITCH
SW3. The signal from the probe
selected
is conditioned
and amplified though part of U6 and then connectedto pin 4 of
U7.U7 is
a comparator that functions
asa minimum signal amplitude that can
be
processed.
This stage
is utilized to
discriminate against low-level
"noise" signalsand low energy radiation pulses
that could interfere with the radiation
signals
of interest.
The minimum probe
signatthat can be
processed
at MAXIMUM sensitivity
is 0.050
V-pp. All
signals
exceeding
5 V-pp are limited to protect the internal circuitry. The signal from U7 is
utilized for 2 separate
functions
- an audible click for eachinput pulse
and the digitat signal
(equilivant to the probe signat)to drive the
microprocessor.
The signal
from U7 is connected
to pin 12
of U5 - a oneshot multivibrator that generates
the audible
click for each
pulse.
The signal
from U7 is
alsoconnected
to pin 27
(input PA7) of Ul the microprocessorthat
completes
all of the signal conditioning,
scaling,
linearizing etc.
CoPYRIGHT@
2006
WMB.
JOHNSON
& ASSOCTATES
3.3
SIGNAL
CONDITIONING. CONTINUED
The
output
of U5
is
part of
Ql and
itsassociated
components
comprise
the
audible
part
of thecircuitry andare
utilized
to drivelhe high
efficiency
piezo
electric
speaker
SPK1.
The
pulse
width
of the
audible
pulse
isseveralmilliseconds
and
becomes
a continuous
tone
at approximately
15k cpm.
The
pulse
from
U7
representingthe
probe
signalisconveyed
to
Ul the
microprocessor
for additional
processing,scaling
etc.
Themicroprocessor
also
provides
theanalog
meter
driver
part
of
U3
a
TWM (time
width
modulated
pulse
that
varies
in width
to the
full scale
valueof theinput signal
i.e.input
signal
that
is50%
of
full scale
will causethe
processor
to output
a
pulsewhosewidth
is507oof theduty cycle.
This
pilse
exits
Ul on
pin
29
(PA5
output)
isintegrated
intoa
precision
analog
signal
by C6,C4
& R4 and
provides
U3
a
analog
signal
equilivant
to the
signal
from the
probe
with
conditioning
& scaling
factorsapplied.
Potentiometers
Pl -
p4
(connected
to
Ul) are
the
calibration
controls
for each
range
(Pl: Xl & P4
:X1000).
Potentiometers
P5&P6
are
notutilized
in thisapplication.
Thefront
panel
momentary
switch
SWI turnstheaudioON or OFF
in one
positionand
ZEROS
the
ratemeter
in theother
direction.
An 8
Mhz
precision
time
base
Yl is
connected
to pins
7 & 8 of Ul. U4
is
a
*POWER
UP
RESET"
that
automatically
adjusts
the
microprocessor
to zeroat start-up.
Part
of U3
monitorsthe
battery
voltage
and
provides
a
"LOW VOLTAGE" signal
to
pin 48
(input
PE6)of Ul. SW3
isthemainselector
switch
onthe
front panel
and
chooses
the
modeof operation- OFF,INTERNAL PROBE'
INTEGRATE'EXTERNAL
PROBE
& EXTERNAL
PROBE
INTEGRATE.
COUNTS/}IINUTE
or DOSEoperationareselected
from thefront
panel
switch
SW2.
THE COUNTS/MINUTE
OPERATING
MODE
IS factorycalibrated
anddoesnot require
field
calibration.
The
LED's
connected
to
pins
35
- 42of Ul are
therange
indicators
anddiagnostic
indicators.Figure2
shows
thecalibration
controls
& switches
locatedon
theCPU
printed
circuitboard.
3.3 HIGH & LOW VOLTAGE
POWER
SUPPLIES
Six
"AA" sizebatteries
provides
the
LOW VOLTAGE power
for all
of theGSM-500
circuitry.
The
batteriesare
connected
to
a
positive
powerregulatoron
thePOWER
SUPPLY
pc
board
designated
El. El convertsthe9 VDC to a
very
stable
+5
vdc.
The
output
of El (+5
VDC) isconnected
to
thecircuitry
requiring
+5
vdcandthenegative5
vdc
regulator
U2.
The
output
of U2
(-5
VDC)
is
connected
to thecircuitry
requiring
-5
VDC.
Both
power
regulators
(El &
U2)
have
very
goodregulation
t 57oand
a lowtemperature
coefficient.
TheHIGH VOLTAGE supply
is
comprised
of
a special
high
efficiency
transformer
with a
feedback
windingandoscillator
circuitry
to
generate
a
low ripple'stable
high
vottage.
Theoutput
of
thetransformer
Tl isconnected
to avoltage
doubler
circuitcomprisedof
D1-D4& C3-C7.
Theoutput
of
thedoubler
circuit
isfiltered
in a
pi type
filter and
connected
to thePROBE
BNC
through
Rl. Rl isalso
the
toad
resistor
for thedetector
circuit.
The
HV oscillator
circuitthrough
R4constantly
monitors
the
highvoltage.
R4
providesUl a
lowvoltage
signal
that represents
the
highvoltage.
Any change
in the
highvoltagewill resultin
an
appropriate
increase
or decrease
in the
power
Ql & Q2
provide
the
highvoltagetransformer.
This
"feedback"
is
utilized
to regulate
the
high
voltageto
approximately
!lo/o. Two
potentiometersR15& R7
are
provided
to setthe
correct
voltage
for eachdetector
for the
meterswith dual
voltage
supplies.
Figure3 shows
the
parts
layoutand
theHV
controls
of the
POWER
SLIPPLY.
t
of
WMBJ GSM.sOO
4.0
OPERATING
CONTROLS
& INDICATORS
- FRONT
PANEL
4.T
CONTROLS
. MAIN FUNCTION
SWITCH
CONTROL
SETTING FUNCTION
ALL POWER
DISCONNECTED
TO THE
INSTRUMENT
NOR]VIAL
OPERATING
RATEMETER MODE - CPM OR DOSE
SELECTED
BY FRONTPANEL
DOSE*/CPM
SWITCH - AUTO
RANGING
- RANGEINDICATOR
IN METER
FACE
_ METER
HAS2
DOSE*
SCALEOPTIONS
-
O
-
.2,0
_2. ALL
SCALES
ARE
MULTIPLIED X THE SCALE
MULTIPLIER
HOLDS
& DISPLAYS
TOTAL DOSEIN mR
& TOTAL COUNTS
FOR
DURATION
OF INTEGRATION
PERIOD. INTEGRATES
IN DOSEOR
CPM
MODE
AUTO
RANGING
_
RANGE
INDICATOR
IN METER
FACE.
NORMAL OPERATING
RATEMETER
I{ODE - CPM OR
DOSE
SELECTED
BY FRONTPANEL
DOSE*/CPM
SWITCH - AUTO
RANGING
- RANGE
INDICATOR
IN METER
FACE
- METER
HAS
2
DOSE*SCALE
OPTIONS-0
-.2,0 - I & 0
-
5 & A CPM
SCALE
0
-
500cpm
ALL SCALES
ARE MULTIPLIED X THE SCALE
MULTIPLIER
OFF
TNTERNALPROBE
INTEGRATE rNrrnnAt, ----------
EXTERNAL PROBE
INTEGRATE EXTERNAL......-..- HOLDS
& DISPLAYS
TOTAL DOSEIN mR & TOTAL COUNTS
FOR
DURATIONOF
INTEGRATION
PERIOD.
INTEGRATES
IN DOSEOR
CPM MODE AUTO
RANGING
- RANGEINDICATOR
IN METER
FACE.
* ALL DosE CALIBRATIONS ARE REFERENCEDTo Csl37
4.2 CONTROL
- DOSE/CPM
Selectsthe
operatingmodeof therate
meter
to
measureeither
mR/hror counts
per
minute.
INTERNAL AND
EXTERNAL
probe
responseisautomaticallylinearized
in theDOSE
modefor the
probe
that
hasbeenselected
onthe
PROBE
SELECTIONSWITCH
(SW4
insidethe
housing).Operation
in theCPM modeautomatically
includes
the
DEAD
TIME correctionfor the
probe
that hasbeenselectedon
thePROBESELECTION
SWITCH.
A listingof the
probes
for
each
position
of thePROBESELECTION
SWITCH
isincludedin Section6.2.5
RATEMETER
DOSE
CALIBRATION - WITH NUCLEAR SOURCE.
4.3 CONTROL - SPEAKER/ZERO
Controlismomentary
toggleswitchwith thecenter
neutral.Momentaryoperation
in SPEAKER
direction
turns
speakeronor off.Momentary
operation
in ZEROdirectioninstantly
zerostheratemeter.
THIS SWITCH
IN THE
ZERO MODE IS UTILIZED IN THE CALIBRATION PROCESSTO ACKNOWLEDGE CERTAIN STEPS
IN THE
CALIBRATION PROCESS.
4.4 CONNECTORSFRONT
PANEL
EXTERNAL INPUT - BNC type receptacle
CoPYRIGHT@
2006WMB.
JOHNSON&
ASSOCTATES
5.0
OPERATING
INSTRUCTIONS
5.1
BEFORE
OPERATION
5.1.1
The
operating
characteristics
of
the
probe
supplied
for the
EXTERNAL
INPUT
are
provided
in the
AppEI\tDIX
of tnis
manual
under
PROBE
OPERATING
INSTRUCTION.
Theinternaland
external
probes
must
becalibrated
prior to
operation
with a
radioactive
source
that
hasa calibrated
Csr37source
and
equipment
and
recognize-d
calibration
procedures
for this
type
instrument.
The
internal
probemust
be
dose
calibrated
with a
Cs137only.
The
external
probe
must
becalibrated
by a source
for dose
applications
and
pulserfor contamination
applications.
Theexternal
input
isfactory
calibrated
for
CPM
and
do
no
require
recalibration.
The
high
voltage
settings
from the
factory
aresatisfactory
for operation
with the
probes
purchasedwith
the
instrument.
Any
useof
probes
otherthan
thosesupplied
with
the
instrument
will nullify
theoriginal
calibration.
TheGSM-500
isdesigned
to operate
with 550
and900
\rDC PROBES.
RCfCT
tOthc
APPENDIX FOR THE CORRECT
PROBE
OPERATING VOLTAGE AND
THE MAINTENANCE
SECTION 6.2.2
for High
Voltage
adjustment
procedure
andSECTION
6.2.3
for the
Sensitivity
adjustment
procedure.
5.1.2
NO OTHER
CHECKS
ARE NECESSARY
PRIOR
TO OPERATING
THE GSM-sOO
EXCEPT
TO
OBSERVE
THE DIAGNOSTIC
LIGHTS
WHEN
THE UNIT IS FIRST
TURNEDON.
ThC
iNtCTNAI
microprocessor
analyzes
theinternal
parametersfor
a few
seconds
whenthe
instrumentisfirst
turned
on.
Alt range,
battery
& probe
diagnostic
tights
are
lit for a
fewseconds
to showthey
areworking.
At the
ru111"
tir" the
meter
isdeflected
to approxim
ately
lz scale
to show
it is operating.
The
meterthen
reverts
to
NORMAL operation
with
one
range
light
lit.
Thediagnostic
circuits
connectedto the
BATT & PROBE
lights
continuously
monitor
theCircuitry
for out
of tolerance
rangeoperation.
Battery
vottage
below
6.8
VDC
witl light
the
BATT.
LED. HIGH VOLTAGE
that
isout of
range
(870-930tor gOO
volt
probes)will light
the
PROBE
LIGHT. SATURATION
of a GM detector
in high
radiation
fields
will also
lightthe
PROBE
light'
5.2
INSTRUMENT OPERATION - INTERNAL PROBE-
RATEMETER
5.2.1 Adjust
the
MAIN SELECTOR
switch
to INTERITIAL PROBE for normal
ratemetertype
operation
for the
INTERNAL Probe.
5.2.3 Select
the
mode
of operation
CPM or DOSE with
the
MODE
SWITCH
for the
internal
probe.
CPM
includes
DEAD
TIME correction.
DOSE
includes
LINEARIZATION & DEAD
TIME for the
probe.
Both
corrections
are
automatically
incorporated
in the
MAIN SELECTOR
switchselection
INTERNAL
PROBE
POSITION.
5.2.4
The
main
panelmeterutilizes
2 separate
scales
to assure
maximum
accuracy
for each
type
probe.The
scales
have
been
assigned
to
each
probe for
DOSE
& CPM
type
measurements
for the
INTERNAL
PROBE are
as
follows:
0
- 2mR/hr
scate
(0
- 2000mphr)
: INTERXAL PROBE ----- CPM
DT CORRECTION
= 4OpSEC
5.2.5 Operation
is
fully automatic
in the
INTERNAL modeof
operation
for either
theDOSEor CPM.
The
actual range
is
indicated
by the
red
ledin the
meter
face
locatedby
themultiplying
factor
(Xl, Xl0, X100
& Xf
000)and
the
meter
will auto
rangeas
necessary
to
maintain
anonscale
reading.
copYRrGHT@
2006
WM
B.
JOHNSON
&
ASSOCIATES
WMBJ GSM.5OO
5.3 INSTRUMENT
OPERATION. INTEGRATE. INTERNAL PROBE
5.3.1 The GSM-500 can initially be operatedwith the procedures
specifiedin Section
5.2 INSTRUMENT
OPERATION RATEMETER. Operating parameters
are the samefor CPM & DOSE operation.
The
GSM-500 indicates
the rate of the incoming GAMMA DOSE in mR./hrin the INTERNAL mode
and
indicates
the total GAMMA DOSE in mR that has
beenaccumulatedfor the period of time the signal
was
collected
in the INTEGRATE mode.
The same
is
true for CPM operation.
The CPM indication in
the INTERNAL mode
is in counts
per minute. The CPM indication in the INTEGRATE mode is
the
total counts
accumulate
during the integration period.
The GSM-500 will hold the accumulated
readin3
until switched
to OFF, EXTERNAL PROBE OR DEPRESS
THE ZERO SWITCH when the meter
automatically resets
to Zero.
5.4.1 The EXTERNAL Probe is
designed
to operate
with any of the probes
listed IN SECTION 6.2.5
of this
manual under the probe operating instructions
and in the bottom of the meter housing.The GSM-500
is generally
purchased
with the HP-265 (pancake
probe).
The HP-265 is
a very versatile
probe that crr
measure
most
alpha,
beta and gamma radiation. This probe
can be read on the DOSE or CPM scalebg
adjusting the switch
on the front panel.
The HP-265 will come
calibrated in Dose
(0
- 200 mR/hr -
Cs137)
and CPM calibrated. The doseis read on the 0-.2
mR/hr scaleand the muttiplier (Xl, X10,
X100 &X1000). CPM is read
on the 0
- 500
CPM scaleX the multiplier (Xl, X10, X100 &, X1000).
5.5.1 The
GSM-500
MAIN SELECTOR
SWITCH
must
beadjusted
to theINTEGRATEINTENAL positior
and the CPM/DOSE switch
adjusted
to DOSE for this mode
of operation.
Operating parameters
are
samefor CPM & DOSE operation.
The GSM-500 will indicate
the accumulatedincoming GAMMA
DOSE in mR for the time the signal
hasbeenintegrated.
The sameis
true for CPM operation when thc
CPM/DOSE switch is
placed
in the CPM position.
The CPM indication in the INTERNAL modeis in
counts
per minute.
The CPM indication in the INTEGRATE mode
is the total counts accumulated
during the integration period.
The GSM-500 witl hold the accumulated
reading until switched to OFF.
EXTERNAL PROBE OR DEPRESS
THE ZERO SWITCH when the meter automatically resets
to
Zero. If the TIMED COUNT option hasnot been
purchased
the integration time witl have
to be
measured
manually.
If the TIMED COUNT option has
been
purchased
then the meter will accumular
the DOSE or CPM for the time setand stop after the predetermined
period has
elapsed.
The meter nfl
continue
to hold the integrated
dose
or cpm until the RESET switch has
beendepressedor the meter
b
turned OFF.
5.6INSTRUMENT
OPERATION
WITH OPTIONAL ALARM
5.6.1 The
GSM-500
can
beequipped
with anAUDIBLE
ALARM that
operateswith a
predetermined
set
point has
been
exceeded
by the incoming
signal.The alarm is
adjusted
by using
a screwdriver to adjut
the alarm set
point P5
asshown
on Figure 2 (P5
is located
in upper left part of Figure 2).
The alarm I
point is
continuously
adjustable firom
5o/oon the Xl scale
to 95o/o
on the X1000 scale.When the ALA
SETPOINT can
be adjusted
the PROBE LED wilt blink If no alarm is required then P5 should
be
adjusted
full clockwise
to prevent
any alarm. Usethe following procedure
to adjust the alarm set
poit
coPYRtGHT@
2006
wM B.
JOHNSON
&
ASSOCTATES
5.6.2 ALARM SETPOINT
PROCEDURE:
5.6.2.1
Remove
the
GSM-500
bottom
housing
by
unlatching
the
end
latchesand
removingthebottom
housing.
5.6.2.2
Turn the
MAIN SELECTOR
switch
to
the
EXTERNAL
PROBE.
BesureSW4
isin
the
0
operating
Position.
5.6.2.3
Locate
P5on
theupper
right side
of the
CPU
circuit
board'
5,6.2.4
Depress
SW5
onthe
upper
left side
of
theCPU
circuit
board.
Panelmeterwill now
display
alarm
set
point.
The
set
point
isdisplayed
just likea
actual
meter
reading
(read
themeter
X the
multiplier
below
the
meter
scale).
5.6.2.5
Adjust
P5until
the
correct
set
point
isdisplayed.
When
thecorrect
set
point
hasbeensetdepress
SW5
again
and
the
meterwill return
to
normal
operation.
5,6.2.6If
a
alarm
set
point
isrequired
on
the
INTERNAL
PROBEadjust
the
MAIN SELECTOR
SWITCH
to
the
EXTERNAL
PROBE
and
repeat
steps
5.6.2.4& 5.6.2.5.
5.7.1 TheGSM-500
can
beequipped
with a TIMED COUNT
option
that
permits
the
INTEGRATION
on
the
incoming
signal
for a
preset
period.
When
this
feature
isused
themeter
will integrateover
the
preset
period
"nd th"n holdthe
final
integrated
signal
indication
onthe
panel
meteruntil
theRESET
(ZERO)
iwitch isdepressed
or the
meter
isturn OFF.
The
TIMED COUNT
SELECTED
will be
displayedon
the
panel
meter.
Thetimes
available
are,
0o
1,5,
10,30and
60seconds.
Thesetimes
are
listedonthe
TOPof
lhe
panetmeter
scales
in circles FIGURE
4
shows
an
exampleof
a scalewith
theINTEGRATE
rlME
markings. qy
The
procedure
for using
this
feature
isas
follows:
5.7.1.1
Remove
theGSM-500
bottom
housing
by
unlatching
the
endlatchesand
removingthe
bottom
Housing.
5.7.1.2
Turn the
MAIN SELECTOR
switch
to
INTEGRATE
for the
probe
usingthe
TIMED COUNT. Be
sure
SW4
isin the
0 NORMAL OPERATING
position.
5.7.1.3
Depress
SW5
(upper
right side
of
CPUboard)
INTEGRATE
TIME. The
rangeLED turn off
indicating
the
time
potentiometer
P6
(upper
leftside
of CPUboard)
can
nowbeadjusted.
5.7.1.4
Adjust
P6slowly
until the
meter
isclose
to the
desired
counting
time.
TheAdjustment
for time
is
not
proportional.
Whenthe
meter
needle
is
adjusted
close
to oneof
the
presettimesonthemeter
scale
that
will bethe
exact
integration
time.
5.7.1.5
When
the
correct
time
hasbeen
setdepress
SW5
to
store
thetime.
If a different
timeisrequired
on
the
other
probefollowsteps
5.7.1.2
through
5.7.1.5.
5.7.1.6
To see
the
integrate
time
set
for each
probe
turn the
MAIN SELECTORSWITCH
to the
INTEGRATE
POSITION
on
the
probe,
depress
SW5
(do
nottouch
P6or a newtime
will beset)
View
thetime
and
thendepress
SW5
to exit.
mttu : i
to 30
0'lu.T it ht;
\..s."\g$t"$[nuttrttrrt/rrrr/rrurrrrf
0 cFI t0
xl 1
lr0
lrs llul
o66
Figure 4
INTEGRATE TIME METER SCALE
CoPYRIGHT@
2006
WM
B.JOHNSON
&
ASSOCIATES
WMBJ GSM.5O()
SPEAKER
1
2gp6
J
cev
1
pssgJ
EXTERNALPROI}E
OFF
OO
C€
NNERNALPROBE
o ${TEGRATTTNTF.nNAL
O Hfff,RNALPRoBo
O TNTFcRATEnrIf,RNAL
o
J
FRONT
PANEL
CONTROLS
FIGURE 1
copyRtcHT@
2006
WM
B.
JOHNSON
& ASSOCTATES
*ohr-{JU}HHEilFT- | r-
ilpn,;trHHHilH
*_Et
P!
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{-
'J"eFqa
l*lczrnllffi
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CPU/LOGIC
BOARD
P/N
T2290
CALIBRATIONcoNTRoLSANDMAJORCOMPONENTS
FIGURE 2
GoPYRIGHT@
2006
WM
B.
JOHNSON
&
ASSOCIATES
WMBJ GSM-sOI
POWER
SUPPLYBOARD
PINI229I
CALIBRATION CONTROLS
AND MAJOR COMPONENTS
ro
:t
=
1
L
q,
m
CoPYRTGHT@
2006WM
B.JOHNSON
& ASSOCTATES
FIGURE 3
WMBJ GSM.sOO
6.0
MAINTENAI\CE
6.1
TEST
INSTRUMENTS
REOUIRED
* DVM capable
of accurately
reading 0 - 10 vdc to 0.010
vdc with input impedance
of at least20 megC).
* High Voltage voltmeter capableof reading 1500vdc with input impedanceof at least
1000
meg
O.
* Oscilloscope
with at least20 Mhz band pass
and 0.10v-pp input sensitivity.
* Pulse
Generator with variable pulse
amplitude control. Range0 - 500,000
pulsesper minute (8333.33
pps)
variable from 0.0.050
v-pp to 5 V-pp. Accuracy loh or better of indicated output. Pulse
generator
must be
capable
ofoperation with 1500vdc present
at the output ofthe generator.
* 3-4 foot length of coaxial
cable
(Rg 58)
with male BNC connectors
on each
end.
* Refer to FIGURES 2 & 3 and the schematics
in section8.0
for location
of the components
and controls.
6.2TEST
PROCEDURES
6.2.1 TESTING POSITIVE& NEGATIVE
5 VDC
POWER
SUPPLIES
- FIGURE 3
6.2.1.1
RemoveGSM-500
from it's housingby unlatching
thelatches
oneachendof thebottomhousing..
6.2.1.2
Connect
the
DVM to
thebatteries.
Batteriesmustreadat least6.5
VDC.
6.2.1.3
Connectthe
DVM to
TP 2.VTVM shouldread5 VDC
+0.1
VDC.
6.2.1.4
Connect
the
DVM to PIN 6 onJ2.Voltageshould
indicate
-5.0
VDC t 0.f VDC.
6.2.1.5
Thiscomplete
thetestingof the
low
voltage
power
supplies.
6.2.2 ADJUST
HIGH VOLTAGE POWER SUPPLY
- FIGURE 3
6.2.2.1 RemoveGSM-500
from
it's housingby unlatchingthe
latches
oneachendof thebottomhousing.
6.2.2.2 Connect
the
HIGH VOLTAGE voltmeterto
theCENTEROF THE EXTERNAL
GM
DETECTOR
INPUT
CONNECTOR
- LocatedonFRONTPANEL
6.2.2.3
Adjustthe
MAIN SELECTORswitch
to theEXTERNAL
position.
6.2.2.4_
AdjustR15until the
HIGH VOLTAGE reads900VDC
t30 VDC whenSW4
(PROBE
SWITCH)
is
position
#l & 2.
6.2.2.5
Connect
theHIGH VOLTAGE
voltmeterto the
ANODE
OF
THE INTERNAL GM DETECTOR
Locatedon
power
supply
pc
board
6.2.2.6 Adjustthe
MAIN SELECTORswitch
to theINTERNAL
position.
6.2.2.7 Adjust
R7 until HIGH VOLTAGE
voltmeterindicatesvoltagerequiredfor internal
probe
550VDC
t30 VDC SW4
(PROBE
SWITCII) is
position
#4
coPYRtGHT@
2006
WMB.JOHNSON
&ASSOCIATES
WMBJ GSM-57
6.2.2 ADJUST
HIGH VOLTAGE POWER
SUPPLY
- FIGURE
3
- CONTINUED
6.2.2.8
This
completes
adjustmentof theHigh
Voltage
power
supply.
6.2.3 RATEMETER
INPUT
SENSITIVITY
CHECK
6.2.3.1 Remove
GSM-500
from it's housing
by unlatching
thelatchesoneachendof thebottom
6.2.3.2 Adjust
SW4
(probe
selector
switch)to theZERO
(0)
position.
6.2.3.3 Connect
thePULSE
GENERATOR
to theINPUTBNC
receptacle.
6.2.3.4 Adjust
theMAIN SELECTOR
switchto theEXTERNALposition.
6.2.3.5 Adjust
thePULSE
GENERATOR
output
to 250,000
cpmwith anamplitudeof 0.050V-pp.Tb
GSM-500
shouldindicate
it is
countingtheinput
pulses
by an up scaleindication.
If the500
not indicate
up scaleINCREASE amplitude of the input pulses
to 0.100V-p-p. If meter
starts
counting pulses,
checkoutput ofpulser to be sure
ofcorrect amplitude calibration.
6.2.3.6
This
completes
INPUT
SENSITIVITY
adjustment
of theratemeter.
6.2.4 RATEMETERCALIBRATION - ELECTRONIC GENERATOR-
FIGURE 2
GENERAL:
IMPORTANT: rX= GST.sOO IS AN AUTo RAI{GING II{sTRUTTIENT.
THAT AUTOTATICALLY GHANGES UP TO THE TEXT SCALE AT
APPROXIMATELY 'lo5o/o
OF FULL SGALE AND GIIAilGES DOWltl TO Tlt
LOWER RANGE AT APPROXITATELY 85O/O
OF FULL SGALE. UTILIZITE
FULL SGALE VALUES FOR CALIBRATION IS NOT REGOTIMENDED DUt
TO THE PROXITITY OF THE SGALE CHAI{GING FACTORS. THE
RESPONSE ON THE MOST SEIIISITIVE SGALES HAS BEEN SLOWED BY
FILTERII{G TO ITPROVE ACCURACY. T}IE GALIBRATION
POTEI{TIOMETER OI{ THE X{ SCALE TUST BE ADJUSTED VERY
SLOWLY AI{D ALLOW TINE FOR TIIE TETER READII{G TO STABILIZ;I-
The GSM-500 can
be calibrated in COUNTS/MINUTE & DOSE'I at the sametime on the
EXTERNAL
probe
input. A switch
on thefront
panel
selects
theoperatingmode.THE ZERO
POSITION
IS
THE
NORMAL OPERATING
POSITION
AND
CANNOTBE
USEDDURING
OPERATION
CHECKS Checking
theoperation
of thecSM-500
in
CPM WITH THE MAIN
SELECTOR
SWITCH
IN ANY NORMAL RATEMETER
POSITION
(INTERNAL
PROBE,
EXTERNAL
PROBE)
shouldbe
donewith
SW4in FIVE
(5)
PROBE
position.
TheFIVE (5)
POSITION
WILL NOT
ADD ANY CORRECTION
FACTOR
TO THE INCOMING SIGNAL
WILL RESULT
IN THE METER INDICATING WHAT EVER THE INPUT PULSER
IS
OUTPUTING. Checking
the GSM-500 WITH SW4IN THE FM (5) probe position will not
ANY COTTection
factoT
and IS THE RECOMMENDED POSITION FOR CHECKING IF THE
CPM IS INDICATING CORRECTLY.
6.2,4.1 Remove
GSM-500 from it's housing
by unlatching the latches
on eachend of the bottom hou
6.2.4.2 Adjust SW4
(PROBE SWITCH) TO THE FIVE (5)
POSITTON.
coPYRtGHT@
2006
wM B.
JOHNSON
& ASSOCTATES * DOSE
CALIBRATIONREFERENCED
To CsI37
WMBJ GSM-5()O
6.2.4
RATEMETER CALIBRATION
- ELECTRONIC GENERATOR
- FIGURE 2
- CONTINUED
6.2.4.3
Connect
thePULSEGENERATOR
to theINPUT
BNCreceptacle.
6.2.4.4
Adjust
theMAIN SELECTOR
switchto theEXTERNAL
position The
GSM-500
shouldindicate
within
+3o/o
of thereadingonall scales.
6.2.4.5
Adjustthe
pulsegenerator
to 500,000cpmwith a 0.050
V p-p
signalamplitude.
6.2.4.5 Theinstrumentshould
autorangeto theXl000 rangeandindicatefull scale.
6.2.4,6 Adjustthe
pulsegenerator
to
250,000cpmat 0.050V p-p
amplitude. Meter
shouldindicate
507o
of scale
ontheX1000
range.Adjustthe
pulsegenerator
to 50,000
cpmat 0.050V p-p
amplitude.
Theinstrument
shouldindicate
full scaleon the
X100range.
6.2.4.7 Adjustthe
pulsegenerator
to 25,000cpmat 0.050
V p-p
amplitude. Theinstrument
should
indicate507oof
scale
on
theXl00 range.
6.2.4.8 Adjustthe
pulse
generator
to 5,000cpm
at 0.050V p-p
amplitude. Meter
shouldindicatefull
scale
ontheX10scale.
6.2.4.9 Adjustthe
pulsegenerator
to
2500cpmat 0.050V
p-p
amplitude. Meter
shouldindicate
507oof
scaleonthe
x10range.
6.2.4.10
Adjustthe
pulsegenerator
to 500cpmat
0.050V p-p
amplitude.Meter
shouldindicatefull scale
ontheXlscale.
6.2.4.11Adjust
the
pulsegenerator
to 250cpmat 0.050
V p-p
amplitude.Meter
shouldindicate
507oof
scale
ontheXl scale.
6.2.4.12
Thiscompletesthecheckingof the
NON
COMPENSATED
CPM MODE OF OPERATION.
6.2.4.13
To determine
if DEADTIME COMPENSATED
MODE FOR
EACH PROBE
POSITION(SW4)
is
functioningcorrectlycheckasfollows:
PlacetheMAIN SELECTORswitch
in EXTERNALPROBE
Connect
the
pulsegenerator
to theinput BNC connector.
c. Completeas follows
PROBE POSTTTON
(SW4)
a.
b.
#l
#2
SETPULSEGENERATOR
100,000
cPM
25,000cPM
GSM-506
SHOULDINDICATE
140,000
CPM
+25,000cpm
250500
CPM
+5,666pp
theCPM MODE for each
probe.
6.2.4.14
Thiscompletesthecheckingof theDEAD TIME compensationin
CoPYRTGHT@
2006
WMB.JOHNSON& ASSOCTATES
WMBJ GSM.5().
6.2.5TTATEMETER
DOSE
CALIBRATION-
WITH NUCLEAR
SOURCE
- EXTERNAL
DETECTOR
GENERAL: The
GSM-500is
a microprocessor
basedmeter
that automaticallylinearizesthe
gamma
dose
(REFERENCED
TO
Csl37)
signal
for eachtype probe preprogrammed into the metersdata basefor
INTERNAL PROBE. The linearization factors have
beenempirically determined
for this detectr
and are included
in the calibration responsewhen SW4 is adjusted to position
4 (probe selection
switch).
Position4 is
for the GP-1002detector which has
a range of 0
- 2000mR"/hr
referencedto
Csl37.
SW4PROBEPOSITIONS
0 --------------
I --------------
OPERATE
GP-200
HP-265
GP-1001
GP-1002
NO
CORRECTION
GP-1003
GP-1010
uw-r00
TION
1
3
4
6
7 ------------
6.2.5.1Remove
the GSM-500
from it's housing
by unlatching eachend of the housing and remove fron
bottom
housing.
Locate
thePROBE
SELECTOR
SWITCH
SW4onthefront left sideof the
CFG
printed circuit board and adjust to the #4 position
for the EXTERNAL DETECTOR THAT \f
BE
CONNECTED
TO THE EXTERNAL
INPUT.
P4FULL COUNTER
CLOCKWISE
6.2.5.2 Adjust the MAIN SELECTOR switch to MEASURE.
6.2.5.3 Adjust the HIGH VOLTAGE to the voltage indicated
for the detector 550 YDC +20
YDC.
6.2.5.4 Place
the probe
with the PROPER ORIENTATION in a calibrated Cesium 137
gamma radiatil
field.
6.2.5.5 Adjust the radiation field to a known value between
50-75Yo
(0
- 2mVhr) of the Xl range.
6.2.5.6 Adjust Pl on the right sideof the meter until the GSM-500
indicates
the correct reading.
6.2.5.7 The red led
shoutd
be Xl- USE 0 -2 SCALE FOR THE detector TO READ mR/hr.
6.2.5.8 Adjust the radiation field to a known value
between20-40o/o
(0
- 2mR/hr) of the Xl range.
6.2.5.9 Meter should read
true field value
+10o .
6.2.5.10
Adjust the radiation field to a known value between
50-75Vo
(0
- 2mR/hr) of the Xl0 range.
6.2.5.f
1 Adjust P2 until the GSM-500 indicates
the correct value
+107o
on the xlO scale.USE THE 0
- !
SCALE FOR THE DETECTOR TO READ mR/hr.
6.2.5.12
Adjust the radiation field to a known value
between20-40oh
(0
- 2mR/hr) of the X10 range.
6.2.5.13
Meter should
read
true field value
+lDoh
6.2.5.14
Adjust the radiation field to a known value between 50-7Soh
(0 - 20mR/hr) of the X100 scale.
USE THE 0 -2 SCALE TO READ mR./hr.
6.2.5.15
Adjust P3 untit the GSM-500 indicates
the correct value
+107o
on the Xl00 scale.
GoPYRTGHT@
2006
WMB.
JOHNSON
& ASSOCTATES
WMBJ CSIn-SOO
6.2.5.16
Adjusttheradiationfield
to a known
valuebetween
valuebetween
20-400
6.2.5.17
Meter
should
read
true field
value
+l0oh
6.2.5.18
AdjustP4
until theGSM-500indicates
the
correctvalue
+107o
onthe
Xl000 scale.
6.2.5.19
Adjusttheradiation
fieldto
a
known
value
betweenvaluebetween
20-40Vo
6.2.5.20
Meter
shouldreadtrue field
value
+l0o
6.2.5.21
DenresstheRESET
switch
onthe
front panel
towardsZERO
andthiswill SAVE
THE
CALIBRATION POTIMETER
SETTINGS.
6.2.5.22ITETURNSW4TO THE ZERO
(O)
POSITION.
THIS IS THE NORMAL OPERATING
POSITION
6.2.5.23
THIS
COMPLETES
CALIBRATION OF
BOTH
THE INTERNAL
AND EXTERNAL
PROBES
6.2.5.24
AFTER
COMPLETINGTHIS
CALIBRATION ALL OF THE FACTORS
THAT EFFECT
EACH
PROBEI.E.HIGH VOLTAGE,DEAD
TIME COMPENSATION,
DOSE
LINEAIZATION ETC
WILL BE
AUTOMATICALLY APPLIED
WHEN THE MAIN SELECTOR
SWITCH
IS
ADJUSTED
TO THE DESIRED
PROBE
(INTERNAL OR EXTERNAL) THE ONLY OTHER
ADJUSTMENTTHAT WILL BE REQUIRED
BEFORE
OPERATION
IS
WILL THE METER
BE
OPERATEDIN THE CPM OR DOSEMODE. THIS
SWITCH
ISALSO
LOCATED
ON THE
FRONT PANEL.
6.2.6 CALIBRATION OF THE INTERNAL DETECTOR
6.2.6.1
Remove
theGSM-500from
it's housing
by unlatching
each
endof
thehousing
and
remove
from
thebottomhousing.Locate
thePROBE
SELECTOR
SWITCH
SW4
onthe
front left
sideof the
CPU
printed
circuit
boardand
adjustto the#4
position
for theGP-l002
DETECTOR
6.2.6.2 AdjusttheMAIN SELECTOR
switchto INTERNAL
PROBE.
6.2.6.3 AdjusttheHIGH VOLTAGE
to thevoltageindicated
for the
detector
550
VDC
+20
VDC.
6.2.6.4
ADJUST
CALIBRATION POTENTIOMETERS
PI _ P4
FULL COUNTER
CLOCKWISE.
6.2.6.5
PlacetheFRONT
OF THE GSM-500with
theinternal
probe
in thePROPER
ORIENTATION in
a calibrated
Cesium137
gamma
radiationfield.
6.2.6.6 Adiust
theradiationfield
to a knownvalue
between
50-75Yo
(0
- 2mR/hr)
of the
Xl range.
6.2.6.7 AdjustPl ontheright
sideof
the
meter
until
theGSM-500indicates
the
correct
reading.
6.2.6.8 Theredled
shouldbeXl- USE0
-2 SCALE FORTHE detector
TO READ
mR./hr.
6.2.6.9 Adjust
the
radiation
field
to a knownvalue
between20-40o/o
(0
- 2nR/hr) of theXl range.
6.2.6.10
Meter
shouldread
true fieldvalue
+107o
6.2.6.11Adiust
the
radiation
field
to a knownvalue
between
50-7SVo
(0
- 2mR/hr)
of the
Xl0 range.
6.2.6.12
AdjustP2
until theGSM-500
indicates
thecorrectvalue
+107o
onthexl0 scale.
USETHE 0
-
2
SCALEFORTHE DETECTOR
TO READ
mVhr.
6.2.6.13
Adjust
the
radiation
field
to a known
valuebetween20-40Vo
(0
- 2mR/hr)
of theX10
range.
6.2.6.14
Metershouldread
true field
value
+l0oh
6.2.6.15
Adjust
the
radiation
field
to a known
valuebetween
50-7Soh
(0
- 20mR/hr).
of theX100
scale.
USETHE 0
-2 SCALE TO READ mR/hr.
6.2,6.16
AdjustP3
until the
GSM-500indicates
thecorrect
value
+107o
ontheX100
scale.
6.2.6,17
Adjust
the
radiation
field
to a known
valuebetween
valuebetween
20-4}o/o
6.2.6.18
Meter
shouldread
true fieldvalue
+l0o/o
6.2.6.19AdjustP4
until theGSM-500indicates
thecorrectvalue
*107o
ontheXl000 scale.
6.2.6.20
Adjust
theradiationfield
to
a
known
value
betweenvalue
between20-40oh
6.2.6.21Metershouldread
true field
value
+l0o
6.2.6.22DepresstheRESET
switch
onthefront panel
towardsZERO
and
thiswill SAVE
THE
CALIBRATION POTIMETER
SETTINGS.
6.2.7
RAPID TROUBLE SHOOTING
GUIDE
GENERAL: TheRAPID
TROUBLE
SHOOTING
GUIDE is
designedto
provide
a
quick
methodof determining
the
overall
problems
thatexistin
themajor
sections
of
thisinstrument. The
guide
isnot
all
inclusive
andis
best
utilized
asa
diagnostic
aid
prior to undertaking
therepair
of theinstrument. The
sections
coveredbytheRTS
are:
coPYRtGHT@2006WMB.JOHNSON
&
ASSOCTATES
WMBJ GSM.5O
5 VOLT POSITIVE SUPPLY
****:t***'t't*******,t*****x*********************************:f:t*:f*:f:f:t****,f,t!t*****:t*********{.**
6.2.7.1
5 VOLT POSITIVE
& NEGATIVE
POWER
SUPPLIES
6.2.7.2
HIGH VOLTAGE
POWER
SUPPLY
6.2.7.3
NO
METER
MOVEII{ENT
6.2.7.4 AUDIO
OUTPUT
NO 5 VOLT POWER
SUPPLIES
6.2.7.1
TEST
EQUIP.
NEEDED
BATT. LED OFF
VOLTMETER
VOLTMETER
VOLTMETER
VOLTMETER
VOLTMETER
VOLTMETER
CHECK 9 vdc
AT BATT
POSITM TERMINAL -+ --)
FOR 6.5vdc
OF HIGHER
+
+
YES
Y
w
CHECK PIN I OF El --t -t
FOR
6.5vdc
OR HIGHER
J
v
YES
.t
+
CHECKVOLTAGEAT -+ --t
PIN
2
OF El FOR 5
vdc
+ 0.1vdc
Y
I
YES
I
t
v
CHECKVOLTAGE AT
PIN I OF U2 FOR 5vdc --r --t
FORa
0.I vdc
J
v
YES
',
+
CHECK VOLTAGE AT --r -->
PIN 5 OF
U2 FOR
-5
vdc
i 0.1vdc
I
v
Y
YES
J
*
CHECKPINS4&6
OF CONNECTOR
J2 ON LOGIC BOARD
.t
w
YES
I
*
w
RETURN
FOR
REPAIR
& ASSOCTATES
NO -+ -+ REPLACE BATTERIES
NO -+ -r CHECKCOI{NECTORJ2A|{D
WIRING TO BATTERY HOLDERS
NO -) --t REPLACE El DEFECTM
INTEGRATED CHIP
NO -) -+ CHECKWIRING FROM
El TO U2
NO -+ --r REPLACE U2
coPYRlcHT@
2006
WMB.
JOHNSON
-+ -) NO -+ -+ REPLACE
J2
WMBJ GSM-500
6.2.7.2 NO HIGH VOLTAGE
TEST
EQUIP.
NEEDED
*********J.*****************J.********rt*****rr***********************t tr**********************
BATT. LED OFF
VOLTMETER
VOLTMETER
TROUBLE SHOOTING
TIIGH VOLTAGE
METER
CHECK+&-5vdc -+ -+
POWERSUPPLIES
AT
PIN2-EI&PIN5-U2
+
Y
YES
J
v
AT CATHODE (BAR)
ENDOF DI
--) --) NO -t -+ SEE
CHECKBATTERY -) -+ -+ -+ NO -+ -+ REPLACE BATTERIES
FOR 6.5
vdc OR
HIGHER
J
v
YES
+
v
GUIDE 6.2.7.I
oscILI,oscoPE CHECK FOR OSCILLATIONS -+ --r --) NO -+ --) CHECK Ql & Q2
AT PIN 3 OF T2
.l,
Y
YES
J
v
OSCILLOSCOPE CHECK FOR OSCILLATIONS -+ _) --) NO -) -+ REPLACE T2
AT PIN 5 OF T2
+
J
YES
t
J
CHECK FORVOLTAGE AT _) -+ -> NO --' -+ SEND BACK FOR
FOR REPAIR
Y
v
YES
I
v
v
CHECKFORHIGH VOLTS -+ -+ .-) NO .+ -) SEND
BACKFORREPAIR
JIJNCTION
OF RI & R:Z
TIIGHVOLTAGE
METER
copyRrGHT@
2006wM B.JOHNSON&
ASSOCIATES
WMBJ
6.2.7.3
--) NO -+ -+ REPLACE BATTERIES
REFERTO6.2.7.l
- +5vdc
POWER
SUPPLIES
-) --r SEEHV TROUBLE SHOOTING
GAIDE6.2.7.2
GSM-5
SEE
MAINTENANCE SECTKN
NO METER MOVEMENT
TEST
EQUIP.
NEEDED
**********************tr*********J.************J,J,******************************trrrt
't********r
BATT. LED
VOLTMETER
VOLTMETf,R
HV VOLT METER
PULSE
GENERATOR
CHECK BATTERY -+
POSITIVE TERMINAL
w
I
YES
I
v
v
CHECK+ & -
Svdc -+ -,
AT PIN2OFEI &
PIN 5 OF U2
Y
YES
J
*
MEASURE
IMT -r --'
PROBE
BNC
J
I
*
YES
J
PULSE GENERATOR --' --t
PROBE
BNC
- METER
DEFLECTS
+
v
YES
I
v
.t
CHECK PROBECABLE + NO
Y
+
YES
{
Y
REPLACE
PROBE
.t
*
NO
v
J
RETURN
FOR
REPAIR
NO
NO
NO -+ --)
6.2.3
NONE -+ -r REPLACE CABLE
copyRtcHT@
2006
wM B.JOHNSON
& ASSOCTATES
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