Service manual

A DJM3.2 MANUAL

DAY OPERATION

Connect S to SP if

required to use set-

point dial

• level(s) 1 and 2 thermostats open

• Disc. Set-point = dial - max. down reset

LEVEL 1 THERMOSTAT CLOSED

• Discharge set-point = dial + max. up

reset

Level 1

Thermostat

LEVEL 2 THERMOSTAT CLOSED

• discharge temperature = 120ºF

Level 2

Thermostat

6. Room Override with Variable Override Set-Point (day operation only)

Thermostat or

Relay Contacts

1000 to 5000 Ohm

Potentiometer

DURING DAY OPERATION

• when the contact closes, the

set-point will be as set on the pot

NOTE: Set-point MUST BE HIGHER than the normal operating setting or normal reset

amount.

XVIII. CALCULATED SET-POINT READOUT (Base Plus Calculated)

Refer to Section XX for calibration.

The calculated set-point is the actual operating discharge air set-point after all the resets have been

added to the dial set-point. (Also note effect if you have ambient reset with the resistor as noted on Page 16.)

Set-Point Calculation (SPC) = Discharge Dial Set-Point + Resets

The SPC can be read using a DC voltmeter connected across resistor #R124 [¼ watt, 1210 ohms

colour code = brown, red, brown, brown (brown or red)]. This resistor is located next to the R29

temperature readout resistor but is slightly further from terminals M and Q (Β) than R29. The

calculated set-point resistor readout scale is 1 volt = 10ºC. This scale is fairly accurate from 15 to

25ºC. As temperatures approach 45ºC, the scale reads 2 to 4ºC low. DJM3.2s built after the fall of

1995 have terminals added to aid in taking this reading.

Page 22 Revised: 3/11/99