Vulcan-Hart 3-130, Service Manual

Page: 11 / 48

3 – 1
SECTION 3 - ADJUSTMENT/CALIBRATION - A-CONTROL
3.1 SCOPE
This section gives the procedures to be used for the
calibration and specification verification of the VULCAN.
The furnace specifications are given in the Owner &
Operator’s Manual.
3.2 FACTORY REPAIR
DENTSPLY Ceramco maintains a factory repair
department for those customers not possessing the
necessary personnel or test equipment to maintain the
VULCAN. If a unit is returned to the factory for
calibration or repair, a detailed description of the
specific problem should be included to minimize
turnaround time. Call factory for RMA number before
shipping at 909-.795.2461.
3.3 ADJUSTMENTS
3.3.1 DOOR, LIFT DRAG ADJUSTMENT
The lift drag force is controlled by a set of friction
washers on each of the upper pivot arms. If the drag
becomes too stiff (too hard to open and close furnace)
or too loose an adjustment can be made using the
following procedure:
TOOLS : 5/32" Allen Wrench
- Turn the allen head screws on the upper side of the
furnace either clockwise to tighten or counterclockwise
to loosen the drag force.
NOTE:
Equal adjustment should be made on each side. Turn
screws only 1/6 of a revolution at a time when making
adjustment.
Connect DMM to PCB as shown in Figure 7-2:
a. For all 120V Units: Adjust RP# to read 19K-20K Ohms
b. For all 220V-240V Units: Adjust RP3 Fully Clockwise (CW)
3.4 CIRCUIT BOARD CALIBRATION
Calibration of the VULCAN circuit board is performed in
one single step.
3.4.1 REQUIRED TEST EQUIPMENT
- Multimeter
- Pot adjustment tool
WARNING
With control drawer opened, dangerous voltage points
may be exposed. Contact with any of these points could
cause serious injury.
3.4.2 TEMPERATURE
Disconnect the power cord from the wall outlet and
open the control drawer. Connect the black lead of the
ohmmeter to the red thermocouple connection on
temperature meter. Touch the red lead of the ohmmeter
to the leg with a circle on R13. Adjust RP1 to read 1060
ohms on the ohmmeter.
On models A-550 rated at 120V the potentiometer RP3
should be adjusted the following way:
Touch the black lead of the ohmmeter to pin 3 of U3 and
the red lead to the leg of R14, see figure 7.2. Adjust RP3
to read between 19 and 20 Kohm on the ohmmeter. This
adjustment limits the amount of current going thru the
muffle by about 15% in order to comply with safety
agency rulings. For all other models RP3 should be fully
clockwise.
As an alternate circuit board calibration, without the use
of an ohmmeter, bring the furnace temperature to the
desired level. At steady state temperature insert a
thermocouple, connected to a temperature monitor, into
the exhaust opening of the furnace and after
stabilization read the muffle temperature. Compare this
reading with the temperature meter reading of the
furnace. In several steps adjust RP1 to obtain equal
readings. Allow ample time between adjustment steps
since only a few watts are added/subtracted which each
adjustment of RP1.
Black Lead to U3
Pin 3 Here
Front of Control Drawer
Figure 7-2
Red Lead to
R14 Here