MODEL 12V500 NEWPORT_ RI

1. MODEL 12V500 “DUPLEX” ALCOHOL BREATH TEST SIMULATOR OPERATION, REPAIR & CALIBRATION

MODEL 12V500
“DUPLEX”
ALCOHOL BREATH TEST SIMULATOR
OPERATION, REPAIR & CALIBRATION
CMI USERS NEWPORT, RHODE ISLAND
AUGUST 17 – 20, 2025
PRESENTED BY GUTH LABORATORIES, INC

2. INTRODUCTION

ED T. SVIRBELY
ETSVIRBELY@GUTHLABS.COM
GUTH LABORATORIES, INC
590 N. 67TH ST.
HARRISBURG, PA 17111
800-233-2338
FAX: 717-564-2555
WWW.GUTHLABS.COM

3. FEATURES OF THE 12V500

Duplex Temperature Monitoring
Microprocessor controlled circuit to maintain 34ºC (heater control)
Independent circuit for monitoring display temperature 34°C
(digital thermometer).
Specification 34°C +/- 0.05°C
Controlled Head space heater
Warm up time of solution & head space <10 minutes
One piece machined top housing allows for uniform heating of inlet
and outlet; i.e. elimination of condensation
► Headspace conditioner (attached to agitator shaft in headspace)
provides uniform headspace temperature.
Operational messages displayed on LCD instead of codes
12VDC operation.
U.S. Patent no 7,895,878 & 8,667,829

4. Effect of Temperature on Simulator

► For every 0.10°C the simulator value (0.10% solution)
changes by 0.0007%.
Example: If simulator is 34.2°C, we would expect to see a 0.1014%
on the Intoximeter EC/IR II.
► NHTSA specifications for Simulators: 34°C +/- 0.2°C
12V500 will alert operator with operational message if temperature
is outside of NHTSA specifications.
► Status Code 4 (<33.8°C), Status Code 7 (>34.2°C)
► Repair of simulator.
► Guth Specifications 34°C +/-0.05°C
Duplex monitoring; 2 independent circuits, one for heater and one
for digital display and operator is alerted by operational message if
2 circuits do not agree within +/-0.05°C:
► Status Code 8: calibration needs adjusted.

5. 12V500 COMPONENTS & FUNCTIONS

12V500 COMPONENTS & FUNCTIONS

6. 12V500 COMPONENTS & FUNCTIONS

12V500 COMPONENTS & FUNCTIONS

7. Normal Display Operation

Power Switch Turned on
Warm UP
Solution
Temperature
Overall Temp
indicator
Cap Heater
Normal Display after Warm Up

8. Calibration Procedure

Equipment Needed for Calibration
► NIST traceable Digital Thermometer (able to read at least
to hundredths).
► Large Slotted Screwdriver to remove white seal plug from
calibration plug on top of simulator.
► Small precision slotted screwdriver to access mode switch
to place simulator in calibration mode; and access to VR1
&VR2.

9. CALIBRATION

A-D Converter 12 Bits = 4096 Steps
Reference Voltage = 4.096 vdc
Therefore: 4.096vdc/4096 steps =
.001vdc/step = .01ºC / step
At 34.0ºC = 3.40vdc = 3400 steps

10. CALIBRATION

Consists of a Bridge Circuit (i.e.. a balance)
What goes in = What comes out
Circuit Components:
► 2 voltage dividers:
R1 R3 R2 R4
Rt (Probe) =2000 @ 25ºC =1423 @34ºC
VR1 &VR2
► Instrument Amplifier U1
► 2.5 vdc Reference Voltage

11. Calibration Procedure

1.
With power off to the simulator, fill the container with
500ml of water or solution.
2.
Using a large slotted screwdriver, remove the white
seal plug from the calibration port on top of the
simulator(Be careful not to strip or damage the slot in
the white seal plug; a dime works well.).
3.
Insert the probe of your NIST digital thermometer
through the calibration port until the bottom of the
probe is at the same depth as the bottom of the
temperature probe. You will have some resistance as
the probe penetrates the rubber grommet in the baffle
plate. This is normal, and will hold the probe in place
once it is at the right depth in the solution.

12. Calibration Procedure

4.
With simulator facing you so display is visible,
locate the calibration label on the right side of the
top housing and remove the label to expose the 3
access points to calibrate the simulator.
MODE SWITCH
Make sure the digital thermometer is positioned
next to the simulator so that you can see both
the digital display of the simulator and the digital
display of the thermometer.
VR1
HEATER ADJSUSTMENT
VR2
DISPLAY/THERMOMETER

13. Calibration Procedure Continued

5.
Insert the small slotted screwdriver into the
mode switch and depress and hold while at
the same time turning the simulator on.
The simulator will power on and give two beeps.
You can release the screwdriver and remove it
from the mode switch. The display should read;
“Calibration Mode”. The simulator will perform a
diagnostic check. If any problems are
encountered a status code will be displayed. If
the simulator passes the diagnostic check, you can
proceed with the calibration procedure.

14. Calibration Procedure continued

6.
If the simulator passes the diagnostic check, you should see the display
with a temperature reading indicating the display for the heater circuit.
(heat wave symbol to the left of the temperature reading on the display
of the simulator).
Insert the small slotted screwdriver into the VR1 opening and adjust to
match the temperature on your NIST traceable digital thermometer.
DECREASE
TEMPERATURE
(CCW)
INCREASE
TEMPERATURE
(CW)

15. Calibration Procedure continued

7.
8.
Insert the small slotted screwdriver into the mode switch and press to
advance to the VR2 circuit for the display/thermometer display
(thermometer symbol to the left of the temperature reading).
Insert the small slotted screwdriver into the VR2 slot to adjust the
digital display on the simulator to read the same as the NIST digital
thermometer.
DECREASE
TEMPERATURE
(CCW)
9.
INCREASE
TEMPERATURE
(CW)
Insert the small slotted screwdriver into mode switch and press to enter
final calibration screen. Simulator will now heat up to near 34°C.

16. Calibration Procedure continued

10. Once simulator has heated up to near 34°C (display in final calibration mode),
insert small slotted screwdriver into VR2 and adjust the display to read the same as
the display on the digital thermometer (note heat wave symbol on CAL screen;
pulsing on and off indicates temp is at the set point near 34°C).
11. Insert small slotted screwdriver into VR1 and watch heat wave symbol to change
set point (increase temperature CW; decrease temperature CCW) until
temperature is 34°C. No need to watch digital thermometer display only heat wave
symbol on CAL screen as you change temperature set point until display now reads
34°C.
12. Confirm new set point with digital thermometer and adjust as necessary with VR1
(small changes with slotted screwdriver will require some time and patience).
13. Insert slotted screwdriver into VR2 now to match display with digital thermometer.
14. Insert slotted screwdriver into mode switch to exit calibration and return to normal
operating display.

17. Checking Calibration

The preceding procedure (full calibration) for calibration only needs to
be performed after doing a repair, i.e. replacement of temperature
probe, heater, motor, or control board.
► It is recommended that the temperature of the simulator be checked
at least once/yr. using an NIST traceable digital thermometer or follow
your department/agency SOP/SOGs for checking the calibration of the
simulator.
► When checking the temperature calibration with an NIST traceable
thermometer ensure that the temperature probe of the digital
thermometer is at the same depth in the solution as the heater and
temperature probe of the simulator to obtain an accurate reading of
the solution in the simulator.
► The NIST traceable thermometer should read 34°C +/- 0.05°C. If the
digital thermometer is outside this range the simulator needs an
adjustment in the calibration.

18. Calibration Adjustment

Features of the duplex probe will alert the operator with an operational
message if there is not a 0.05°C agreement between the two
temperature sensors.
► To perform a calibration adjustment, you need to place the simulator in
the calibration mode.
► With the simulator turned off, insert a small slotted screwdriver into
the mode switch and turn the power on. If the simulator passes the
diagnostic test, advance to the final calibration by inserting the small
slotted screwdriver into the mode switch to advance to the display
below(press mode switch 2 times to advance to cal adjust screen).
Calibration

19. Calibration Adjustment (cont.)

Insert small slotted screwdriver into slot VR2. Adjust the digital display
on the simulator to read the same as display temperature on digital
thermometer.
► Watch heater indicator light on right of calibration screen on digital
display of the simulator.
► Insert small slotted screwdriver into slot VR1. Watch heater indicator
on display of simulator and adjust accordingly until digital display on
simulator is 34°C +/- 0.05°C.
► Adjust the Digital Display again with VR2 if necessary to match digital
display on digital thermometer.

20. 12V500 REPAIRS

► Easy access to motor
No need to remove circuit board
Disconnect cover (display) and power switch from control board
and remove agitator and baffle plates to access the 2 screws
holding motor from the bottom of the top housing to remove the
motor.
► Components are surface mount = board replacement
► Single probe housing with 2 Thermistor beads
Heater control
Temperature/Display
► Blow Pipe end removable for easy cleaning or replacement

21. Inside the 12V500

ON/OFF SWITCH
DISPLAY BOARD
TEMPERATURE PROBE
CAP HEATER
VR1
VR2
MODE SWITCH
MOTOR
DC 12V POWER SUPPLY
RS232 COM PORT

22. Duplex Temperature Probe Replacement

Use a multimeter to determine if
the Duplex Temperature probe
needs replaced.
► Resistance readings of probe wires
is determined by the temperature
of the water.
► If readings on the multimeter are
different that what the range is on
chart, replace the probe.
TEMPERATURE °C
RESISTANCE
20
2258-2608
20.5
2210-2560
21
2164-2514
21.5
2118-2468
22
2073-2423
22.5
2030-2380
23
1987-2337
23.5
1945-2295
24
1904-2254
24.5
1864-2214
25
1825-2175
25.5
1787-2137
26
1749-2099
26.5
1713-2063
27
1677-2027
27.5
1642-1992
28
1608-1958
28.5
1574-1924
29
1541-1891
29.5
1858-1509
30
1477-1827

23. Checking Duplex Temperature Probe & Heater

Checking Duplex Temperature Probe & Heater
PROBE
► With Multimeter set to resistance Check resistance of:
2 white wires
2 black wires
If readings are outside of acceptable range probe is defective
► Any readings of resistance of :
Black to white
Black to ground of housing
White to ground of housing
HEATER
► Resistance of heater = 2.2Ω
Any resistance of wire to housing heater is defective

24. TROUBLESHOOTING

Look for obvious signs of problems:
Leaks. Check simulator for leaks. Common problems, bad container
gasket; bad sure lock connector or worn o-rings. Loose component
connectors. Factory trained personnel can use a vacuum gauge to check
for leaks. Exercise caution not to over pressurize simulator.
Check for broken and or chips around threads on glass container. Replace
if found.
Algae build up. Follow instructions as outlined in operator’s manual. Build
up of algae on temperature probe can cause erratic temperature readings
and hard to adjust calibration to specification.
Temperature. Can be ambient conditions or problem or malfunction of
simulator.
Internal Diagnostics will check conditions to prevent the simulator from
operating if the proper temperature is not maintained. The simulator
will display Error on the display and Error message until the
malfunction is corrected or simulator is reset.

25. TROUBLESHOOTING CONDITIONS OUTSIDE NORMAL OPERATIONS

For any Messages displayed on the 12V500, try to reset the simulator by
turning the simulator off (reset) and turning the simulator back on. If
the error is displayed again, further troubleshooting and or service is
needed.
Check container for presence of solution.
► If flow rate is to high; equilibrium of stirring of solution is interrupted
and may cause the no solution message.
► Improper alignment of dispersion tube (blow Pipe) in relation to
agitator.
Temperature sensor for heater circuit is either open or shorted.
Cannot be Remedied in the field Requires service.

26. TROUBLESHOOTING CONDITIONS OUTSIDE NORMAL OPERATIONS

The Temperature sensor for thermometer (display) is open or shorted.
Can’t be remedied in the field requires service.
The Temperature of solution is > 34.20°C after initially reaching 34.00°C.
Turn off simulator and allow to cool. Turn simulator back on. If condition continues
simulator needs to be recalibrated or other service is needed.
Ensure that the agitator is spinning. Motor may need replaced.
The Temperature of solution is < 33.80°C after initially reaching 34.00°C.
Turn off simulator and allow to cool. Turn simulator back on. If condition continues
simulator needs to be recalibrated or other service is needed.

27. TROUBLESHOOTING CONDITIONS OUTSIDE NORMAL OPERATIONS

Excessive amount of time for solution temperature to increase.
Heating element may be open or solution was too cold.
Try to reset simulator. If condition continues, simulator needs serviced.
► The temperature control circuit and thermometer (display) are reporting
different temperatures.
Recalibrate simulator.
► Agitator not spinning.
Turn simulator off and remove container to check for corrosion around motor shaft. Manually
spin agitator by hand. If it spins freely reassemble and turn on. If condition continues motor
may need replaced or other service is required.

28. TROUBLESHOOTING CONDITIONS OUTSIDE NORMAL OPERATIONS

Temperature of top housing has dropped below 34.5°C after initially reaching
set point (35. 0°C).
Turn off simulator and mover to warmer environment. Wait few minutes and turn back on. If
condition continues, simulator requires service.
► Temperature of top housing has risen above 36.0°C after initially reaching set
point (35.0°C).
Turn off simulator and mover to cooler environment. Wait few minutes and turn back on. If
condition continues, simulator requires service.
Excessive amount of time for housing temperature to increase.
Reset simulator. Heating element may be open or top housing was too cold. Requires service.