MST 5700 User manual

IMPORTANT WARNING
WHEN THE CO MONITOR IS CORRECTLY INSTALLED AND
MAINTAINED, IT MONITORS THE LEVEL OF CARBON
MONOXIDE IN THE RESPIRATORY AIR LINE. THE MONITOR
DOES NOT
REMOVE CARBON MONOXIDE FROM THE AIR
MST, INC.
MODEL 5700
MICROPROCESSOR
MONITOR
OWNER’S
MANUAL
2/12

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MODEL 5700
SPECIFICATIONS
MST, INC. MODEL 5700 CARBON MONOXIDE MONITOR AND ALARM
RANGE: 0-199 PPM CO SERIAL NUMBER:
INITIAL ALARM SETTING: U.S.: 10 PPM CO POWER: 9 V ALKALINE BATTERY
Canada: 5 PPM CO (Transistor type) - 2 each
DETECTOR TYPE: ELECTROCHEMICAL CELL
CONTENTS
INTRODUCTION ........................................................................... 3
DETAILED DESCRIPTION ................................................................... 4
FRONT PANEL ...................................................................... 4
ON/OFF/TEST SWITCH ....................................................... 4
DISPLAY ................................................................... 4
SPAN AND ZERO ADJUSTMENTS .............................................. 4
LEFT SIDE ......................................................................... 4
BUZZER .................................................................... 4
ALARM LIGHT .............................................................. 4
LOW BATTERY LIGHT ....................................................... 5
NORMAL LIGHT ............................................................. 5
REM ALARM ................................................................ 5
BOTTOM .......................................................................... 5
RIGHT SIDE ........................................................................ 5
BATTERY COMPARTMENTS .................................................. 5
AUXILIARY POWER JACK .................................................... 6
OPERATION ............................................................................... 6
PRELIMINARY ..................................................................... 6
NORMAL OPERATION ............................................................... 7
ABNORMAL INDICATIONS .......................................................... 7
LOW BATTERY .............................................................. 7
DETECTOR OPEN CIRCUIT ................................................... 8
DISPLAY WILL NOT READ UPSCALE .......................................... 8
DISPLAY GOES OFF SCALE ................................................... 8
DISPLAY GOES BELOW 0 ..................................................... 8
CALIBRATION AND ADJUSTMENT .......................................................... 9
ZERO ADJUSTMENT ................................................................ 9
SPAN ADJUSTMENT ................................................................ 9
ALARM ADJUSTMENT .............................................................. 9
MAINTENANCE ........................................................................... 10
BATTERIES ....................................................................... 10
DETECTOR ....................................................................... 10
MAIN CIRCUIT BOARD ............................................................. 11
OTHER COMPONENTS ............................................................. 12
REPAIR ........................................................................... 12
ACCESSORIES ............................................................................ 12
PARTS LIST .............................................................................. 14

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MODEL 5700
I. INTRODUCTION
The MST, Inc. Model 5700 Carbon Monoxide (CO) Monitor and Alarm is a side mounted, battery
powered unit. The monitor has been designed, and is certified by the Canadian Standards
Association (CSA LR-104195) to be INTRINSICALLY SAFE FOR USE IN CLASS 1, DIVISION
I, GROUPS A,B,C&D when used with two “9V” alkaline transistor type batteries. When the
monitor is powered by the same two “9V” alkaline batteries, the optional Alarm Repeater, (P/N
80444 - see accessories VI.A), is certified INTRINSICALLY SAFE under the same Certification No.
for the same Class/Div/Groups as mentioned above. An internal microprocessor controls the
indication and alarm functions in response to the indicator of an electrochemical CO Sensor.
It continuously monitors a compressed air sample introduced to its detector at an approximate rate
of 1.0 SCFH and it gives an alarm when:
!The CO in the sample exceeds a preset level (adjustable-initially set at 10 PPM; 5 PPM in
Canada).
!The battery voltage has diminished to a preset level (non-adjustable).
!There is a discontinuity in the detector circuit.
There are also indicators to show CO concentration and to verify that the instrument is on and
operating properly.
The components are assembled into a black powder-coated aluminum housing 6" H x 4" W x 2"
D overall. A hose barb, with plastic sample tube attached for introducing the sample gas, extends
from the bottom. Available at the front face are the OFF/ON/TEST switch, the display (LCD),
SPAN and ZERO adjustments.
The left side contains the indicating lights, the alarm buzzer, and the remote alarm jack. Accessible
on the right side are the two battery drawers and the auxiliary power jack.
These items are detailed below.

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MODEL 5700
II. DETAILED DESCRIPTION
General descriptions of each of the items mentioned in the previous section are provided below.
Their functions are indicated in Section III, OPERATION.
A. FRONT PANEL
1. ON/OFF/TEST Switch
This switch is a three-position type with alternate ON and OFF positions, and a
momentary TEST position. Switch is located at the lower left side.
2. Display
Display is a centrally located LCD type and is refreshed every 0.8 seconds; the
red ALARM light faintly blinks at the same time.
3. SPAN and ZERO Adjustments
Located to the right of the display are two miniature multi-turn slotted-shaft
potentiometers, accessible through holes in the panel with a small screwdriver.
B. LEFT SIDE
The items listed below are aligned toward the rear from the center of the left side panel
and from top to bottom are:
1. Buzzer (Piezoelectric - 85 dB(A) at 1 Ft.)
Buzzer is at the top of the side panel. It provides a continuous tone during high
CO alarm, a pulsing tone during certain malfunction conditions.
The next three items are colored LED indicating lights that come on when various
conditions, described later, are present.
2. ALARM light
Red ALARM light blinks faintly during normal operation and is on steadily
during the high CO alarm condition.

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MODEL 5700
3. LOW BATTERY Light
Amber LOW BATTERY light comes on when battery voltage falls to where the
instrument will not function properly (about 7. 0V). Batteries should be replaced
at this time.
4. NORMAL Light
The green NORMAL light acts as a pilot light and glows when the instrument is
turned on. At the same time the red ALARM light flickers faintly at intervals of
about one second.
5. REM ALARM
Aminiature size phone jack is provided for plugging in a remote alarm device so that
the alarm sound can be repeated at a distance from the instrument. The outer shell
of the jack is grounded to the case, and is negative. This jack will be energized at
battery voltage (about 8.5 VDC when operating from “fresh” internal batteries; about
8.9 VDC when operating from continuous operating adaptor, P/N 80247 and about
12 VDC when operating from an external 12 volt battery )whenever instrument is in
alarm condition. The P/N 80444 Alarm Repeater is CSA Approved as a remote
alarm device.
.
WARNING:
THE INTRINSIC SAFETY OF THE INSTRUMENT IS VOIDED WHEN ANY
OTHER ACCESSORY IS USED AT THE REM. THE IMPEDANCE OF ANY
CONNECTED LOAD DEVICE AT THE REM MUST BE AT LEAST 22 OHMS (FOR 12
VDC OPERATION) OR AT LEAST 12 OHMS (WHEN OPERATING FROM INTERNAL
BATTERY OR CONTINUOUS OPERATING ADAPTER, P/N 80247) TO AVOID DAMAGE
TO THE INTERNAL CIRCUITS.
C. BOTTOM
Arectangular opening in the bottom allows clearance for the detector which is mounted
to the upper face of the bottom plate. The bottom plate is held in place by two knurled
thumbscrews. The sample inlet fitting and tubing extends from the outer face of the
bottom plate.
D. RIGHT SIDE
These items are aligned toward the rear of the right side panel.
1. Battery Compartments
There are two battery compartment drawers near the top. They contain the two
9V “transistor” type alkaline batteries, connected in parallel, which power the
instrument.

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MODEL 5700
2. Auxiliary Power Jack
A2.5 mm pin jack is located near the bottom for operating the instrument from
an auxiliary 12 V battery or from a Continuous Operation Adapter (COA). An
auxiliary battery will extend the time ofoperation considerably, and the COA will
power the instrument as long as power is supplied to it. The outer shell of the
jack is grounded to the case and is negative.
WARNING: THE INTRINSIC SAFETY OF THE INSTRUMENT IS VOIDED WHEN P/N
80247 CONTINUOUS OPERATING ADAPTER OR P/N 80123 12 VDC ADAPTER IS IN
USE.
III. OPERATION
A. PRELIMINARY
1. Turn instrument on and allow about 5 minutes to stabilize. Verify that the amber
LOW BATTERY light is off. (See MAINTENANCE, V.A.)
2. Push up and hold switch in the TEST position.
a) The red ALARM light will come on verifying the CO alarm circuit
operation.
b) The amber LOW BATTERY light will also come on, verifying the low
battery detection circuit.
c) Green NORMAL light will blink several times, then come on steady
verifying continuity of the detector circuits.
d) The buzzer will sound and the REM ALARM jack will be energized.
e) The display will show an upscale reading.
f) Release the switch. Indicators will return to normal and display may first
show a negative indication (-XX), then return close to 00.
3. Remove sample inlet tube from sample metering valve outlet fitting and introduce
asample of zero air or nitrogen, free of CO and interfering gases, to the sample
inlet tube. The sample flow should be between 0.5 and 1.5 SCFH.
4. Verify that the green NORMAL light is on, the red ALARM light is flickering
about once a second and the display is showing 00 (zero), (see Calibration and
Adjustment, IV.A).

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MODEL 5700
5. Remove the zero air sample and introduce a known sample of 50 to 150 ppm CO
to the sample inlet tube. The sample flow should be between 0.5 and 1.5 SCFH.
6. Verify that the display readings rise upscale and the alarm light and buzzer
operate (See Calibration and Adjustment, IV. B).
7. Remove the CO sample.
8. Insert the sample tube into the metering valve outlet fitting and lock in place.
9. Instrument is now ready for normal use. Turn OFF when not in use.
MONITOR CALIBRATION FREQUENCY:
MONTHLY CALIBRATION*: If monitor is used on continuous basis, (daily or weekly use).
PRIOR TO USE CALIBRATION*: If monitor is used on a non-continuous basis.
*If monitor’s alarm is energized, always check calibration to be sure monitor is not malfunctioning
and or out of calibration producing a false alarm/reading.
B. NORMAL OPERATION
1. Instrument will analyze the sample and show CO content on the display, in parts
per million (PPM). The green NORMAL light will glow continuously and the
red ALARM light will flicker about every second.
2. When the CO concentration exceeds the alarm point (initially set at 10 PPM, 5
PPM for Canada) the red ALARM light will come on steady, the green NORMAL
light will go off, the buzzer will sound a steady tone, and the REM ALARM jack
will be energized.
3. When the CO concentration drops below the alarm setting, the indicators will
automatically return to normal as in paragraph 1 above.
C. ABNORMAL INDICATIONS
1. Low Battery
As the battery voltage declines toward the end of its life, the following indications
occur, which assure that the problem will not be overlooked:
a) At 7.0 volts, the amber LOW BATTERY light will come on. Battery
replacement is recommended at this point, but continued operation is still
possible.
b) At 6.4 volts the buzzer will beep at intervals of about 7 seconds.

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MODEL 5700
c) At 5.8 volts the buzzer will beep at 1-second intervals and the display will
go to --. This malfunction indication will continue until the battery is
completely dead.
2. Detector (cell) open circuit
If there is a discontinuity in one or more of the detector leads, or internal to the
cell itself, the following malfunction indications will occur:
Open Wire Green Pilot Amber Light Red Light Buzzer Display
Red (SENS) pulsing off pulsing pulsing SC
Black(CNTR) pulsing off pulsing pulsing SC
Blue (REF) off off steady steady +1 or 199
All pulsing off pulsing pulsing SC
3. Display will not read upscale.
If the display will not move from zero (00) when detector is exposed to sample of
CO:
a) SPAN adjustment set to zero--recalibrate SPAN and set ZERO.
b) Cell has lost sensitivity--replace cell.
c) Circuit malfunction--repair is needed.
4. Display goes off scale (1).
a) CO concentration greater than 199 ppm.
b) REF wire disconnected or cell has internal failure.
c) Circuit malfunction; repair is needed.
5. Display goes below 0 (-02,-1 or SC).
a) ZERO misadjusted--readjust as in paragraph III. -A-1 through 5.
b) SENS, CNTR or all wire(s) disconnected or cell has internal failure.
c) Circuit malfunction--repair is needed.

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MODEL 5700
IV. CALIBRATION AND ADJUSTMENT
After each adjustment in the following steps, allow time for the changes to stabilize. Recheck all
adjustments. Turn instrument on and allow at least 5 minutes warm-up before calibration and
adjustments are made.
A. ZERO ADJUSTMENT
1. Remove sample inlet tube from sample metering valve outlet fitting and introduce
asample of zero air or nitrogen, free of “CO” and interfering gases, to the sample
inlet tube. The sample flow should be between 0.5 and 1.5 SCFH.
2. Verify that the green NORMAL light is on, the red ALARM light is flickering
about once a second and the display is showing “00". If the display is showing
other than “00", adjust the ZERO potentiometer (next to the display) so that the
reading is “00". Clockwise adjustment increases reading. Notice that the display
jumps from 00 to +02 to -02. Try to set the potentiometer midway between the
two extremes. Remove the zero air sample.
B. SPAN ADJUSTMENT
To set the span of the instrument, follow the steps below:
1. Introduce a known sample of 50 to 150 PPM “CO” to sample inlet tube. The
sample flow should be between 0.5 to 1.5 SCFH.
2. Verify that the green NORMAL light is off, the red ALARM light is on full bright
and the stabilized reading (after approximately one minute) is equal to the known
concentration of “CO”. If the display is showing a difference, adjust the SPAN
potentiometer (next to the display) to obtain proper value. Turn clockwise to
increase reading. If the span adjustment cannot be made as indicated, the detector
needs to be replaced. SEE MAINTENANCE, V.B.
3. Remove the known sample and return the sample inlet tube to the sample metering
valve outlet fitting and lock in place..
The instrument is now properly adjusted for use.
C. ALARM ADJUSTMENT
The alarm level (initially set as shown on the specification page) can be changed if
desired, as follows:
1. Remove the screw on upper front edge of right side of case.
2. Using a small-blade screwdriver through the screw hole, locate the ALARM
adjustment slotted potentiometer.

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MODEL 5700
3. Set the display reading to the desired alarm level with the ZERO potentiometer.
4. Turn the ALARM potentiometer clockwise until the alarm just activates.
5. Check the setting by turning the ZERO potentiometer CW and CCW to cause the
instrument to go into and out of alarm. Observe display to confirm alarm setting
level.
6. Return the display reading to 00 with the ZERO potentiometer (NOTE: Zero gas
should be used when performing this adjustment).
V. MAINTENANCE
A. BATTERIES
Check batteries each time instrument is turned on by noting that the green NORMAL
light is on and the amber LOW BATTERY light is off. If the amber light is on, the
batteries need replacing.
Batteries are contained in drawers on the right-hand side. To replace the batteries:
1. Pull the small slot in the drawer face toward the front of the instrument to unlatch
the drawer and pull the drawer out of the housing.
2. Pry battery out of drawer with fingers and replace with a fresh 9V alkaline
transistor type battery, providing for proper polarity by placing minus (-) terminal
uppermost in holder. Place bottom of fresh battery against spring and press into
place.
CAUTION: OBSERVE PROPER POLARITY WHEN INSERTING BATTERIES.
POLARITY IS MARKED ON THE INSIDE OF THE DRAWERS.
3. Push drawer back into housing until it latches in place. Drawers inserted
incorrectly will not latch.
4. Repeat above steps for the second battery. (It is possible to operate with only one
battery, but operating hours will be greatly reduced).
B. DETECTOR
If the zero or span adjustments cannot be made within the range of their respective
potentiometers, the detector needs to be replaced. To replace detector: