Grant OPTIMA RANGE GD100, Руководство по обслуживанию

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3 Brief Mechanical Description
The control units are housed in an
upright unit having a metal cover with a
plastic front panel. The control unit can be
mounted on a bridge plate on Grant tanks or
fitted to users own tank by using a Grant
Instruments K clamp.
The GD120 is fitted with a circulating pump
which can only be used in a closed loop
circulation system, for example a jacketed
vessel. It will not circulate liquid through an
open tank. A plastic moulding is provided to
connect output and input pipes for this pump.
When repairing the GD120 ensure that either
a blanking plate is fitted or the pump input
and output is shorted with a piece of pipe.
Mounted below a stainless steel chassis are
the submersible items, stainless steel heater;
temperature sensing probe; stirrer shaft fitted
with propeller; stainless steel float; pump and
stainless steel over temperature cut out. (last
two items GD120 only).
The plastic front panel is mounted on the
base and the display PCB is clipped on to it.
The power supply board is also clipped to the
front panel and its heat sink forms the upper
half of the rear panel.
Mounted on the rear panel is the IEC power
supply socket with the fuses in a drawer
which clips into the socket (240Vunits) or the
cable input (115V) with fuses mounted on the
lower half of the rear panel.
The steel cover is held with screws to the
chassis and the rear panel.
The push button mains switch is operated
through the elastomer front panel which also
has the operating buttons.
4 Description of Operation
4.1 AC Power Distribution and
Component Interconnections
There are two printed circuits in the
unit, the which contains the
power supplies for both boards and the
components for driving the heater triac IC3.
The other board is the
which is screwed to the front panel and
contains the processor and display and is
where the temperature control function takes
place.
The circuit diagrams for these boards are
and respectively.
The component layout diagrams for these
two boards are
and .respectively.
The main connections to the unit and also
the low voltage connections between the two
printed circuit boards and the probe are
shown on the wiring diagrams
and
.
4.2 DC Power Supplies
Refer to the power supply circuit
diagram . The DC power supplies are
obtained from mains voltage through
transformer
mounted on the power supply
PCB. This transformer has two secondary
windings, one drives a full wave rectifier DB1
which produces a positive power supply
across C5 feeding a +5V stabiliser IC4, the
second produces a dc voltage across C7 via
diode D3, giving unstab12V at pin 3.
The low voltage side of the transformer is
connected to the Display PCB through PL7.
4.3 Temperature Measurement and
Control.
The temperature control function is
shared between the DISPLAY PCB and the
POWER SUPPLY PCB
The temperature measurement function is
carried out on the display board and the
temperature control function on the power
supply board.
POWER BOARD
DISPLAY BOARD
Fig
1 Fig 2
Fig 3 Fig 4
Fig 5 Fig
6
Fig 1
T1
GD100/GD120
Part No. 17592/Issue 1
July 2002
Page 7