Service manual

A DJM3.2 MANUAL
3. If there is a BMS system connected to the DJM3 determine if it is necessary to cut R43 before
mounting the control. The best way is to look at the board you are removing.
4. The DJM3.2 uses a Johnson TE 6000 discharge air sensor.
• Turn service switch 5 on to adjust the burner.
• Adjust Pot Hi Service marked “SP” to high fire and set up the burner.
• Adjust low fire.
• Adjust curve-matching pot.
After adjusting the flame, set the following pots:
• Adjust Pot D Sen Cal discharge sensor calibration.
• Adjust Pot Dis SP Cal discharge set-point calibration.
• Turn on any dipswitch that was in use on the existing control. This would usually be to
activate a reset control.
• Note operation of any resets connected, noting reset ratio, room cal etc. as needed.
5. Set dipswitch 7 to configure "maintain purge" operation Section VII.
6. Set dipswitch 8 to configure low limit operation Section X.
Side Wall Venting
There is an air-proving switch that is wired into the speed sensor circuit on indoor units. This is to
prevent any ignition attempt unless airflow through the wall vent is proven.
Main Gas Valve Over Travel Switch (Option)
If the main gas valve does not return to a closed position on completion of a heat call, the contacts
will be open preventing the pilot from lighting.
Simulating a Heat Call
Unlike many controls, you cannot simply open circuit or short-circuit the DJM3.2 discharge air sensor
to simulate a full call for heat or no heat. The DJM3.2 checks the discharge sensor to insure it is
operating between two values. If the sensor is too low in value the DJM3.2 will trip on low limit (value
below 881 ohms). If the sensor resistance is too high, the DJM3.2 will lock out on a bad sensor. The
acceptable sensor values lie between 880 to 4000 ohms. If you wish to simulate a heat call from the
sensor instead of using the manual firing pot then you can do one of the following:
1. Substitute a 950 to 1005-ohm resistor in place of the discharge air sensor, and then adjust the
size of flame with the set-point pot.
2. Substitute a variable potentiometer with values between 850 through 1250-ohms. This will allow
a simulation of the operation of the control with discharge temperatures from about 32 through to
125ºF.
XXIV. MISCELLANEOUS NOTES
Combustion Blower Speeds
DJM3.2 configured for the REGULAR ROUND BURNER
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•
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LOW FIRE COMBUSTION BLOWER SPEED is about 1850 RPM ±10 RPM (30.8 Hz)
HIGH FIRE COMBUSTION BLOWER SPEED is about 3400 RPM
LIGHT OFF SPEED is about 2700 RPM
DJM3.2 configured for the HIGH TURNDOWN BURNER
Page 43 Revised: 3/11/99