Vulcan Quasar 40 gas heater repair

Vulcan Quasar 40 gas heater - clock repair

Gas heater sometimes switches itself off for no reason. This is caused by a faulty electronic clock located near the top of the heater. One sign of failure is the ability to chance the clock setting even with the sliding switch in the "lock" position.

The printed circuit board with the digital clock contains three capacitors. They seem to go bad after some years of exposure to increased temperature and require replacement.

Important warning:

This procedure has been documented for my own use. It is not intended to be followed by other persons who may be unskilled and unqualified to repair electrical equipment.


Essential safety step:

Shut down the heater before repairing it. Extinguish pilot flame, disconnect electrical power to the heater and close off the heating gas.


Step 1

Remove heater hinged lower panel
Step 2

Remove screw on the right securing the outer heater case.
Step 3

Remove screw on the left securing the outer heater case.
Step 4

Remove screw on the right holding the gas valve cover.
Step 5

Remove screw on the left holding the gas valve cover.
Step 6

Remove screw securing cable tie to the outer heater case.
Step 7

Move bottom of the outer heater case away from the heater.
Step 8

Move the heater outer case away from the wall.
Step 9

Lift the heater outer case upwards a little to disengage the top holding brackets (shown here in detail after the outer case was removed.
Step 10

Move the heater outer case sideways carefully a short distance from the heater because it is still connected by wires to the heater.
Step 11

Disconnect the green/yellow earth cable blade connector.
Step 12

Lift the right side of black gas valve cover over the white control block with rotary dial.
Step 13

Lift the left side of black gas valve cover over the fan lever (careful manipulation of the cover is required not to damage the fan lever).
Step 14

Allow the gas cover valve hang loose by its weight taking care not to stress excessively the red cable to the pilot flame igniter.
Step 15

Disconnect two electrical plugs to free the hearer outer case from the heater.
Step 16

When the outer heater cover is removed, the thermostat and overtemp cutout are accessible on top of the hearer. (It may be an opportunity to clean dust from the top of the heater and these two electrical components)
Step 17

Remove two screws holding the metal heat shield over the clock box.
Step 18

The clock box is now visible.
Step 19

Remove two electrical plugs from the clock box and push the box out of front of the heater outer case. (In the process the box must be tilted slightly to clear the two electrical sockets)
Step 20

The clock box can be lifted to reveal two clock circuit boards.
This step is unfortunately not well illustrated. Inside the clock box there are two circuit boards mounted one above the other. The smaller circuit board is placed over the larger board and held in position by four soldered pins on the outer side and two pins in the middle the larger board.
Two pins shown in the blue circle must be desoldered from the surface of the smaller board before the smaller board can be lifted by bending the four pins on its opposite side in order to get access to the electrical components on its underside.
Step 24

Three capacitors that require replacing are shown in the blue circle.
Step 25

When the whole clock with its smaller board is turned upside down, the three capacitors become accessible.
Step 26

Capacitors are clearly labelled in this picture.
When replacing them, take care to maintain correct polarity. Small + signs are shown on the board next to each capacitor.
Specifications of capacitors

part numbers and prices shown as available from company Element 14 (formerly Farnell, phone +61 2 9644 7722,
61 2 1300 316 225)

Capacitor 1: 470 UF/16V, part No.:8126321, cost: $1.58

Capacitor 2: 1000 UF/16V, part No.:1144692, cost: $2.56

Capacitor 3: 10 UF/50V, part No.: 8126992, Cost: $1.89

Step 28

Assembly of the clock box is reverse of the disassembly.

Before replacing the clock box metal heat shield, a heat insulation material (e.g. a strip of car exhaust asbestos tape) can be glued to the other side of the clock box to protect it from long term effects of the heat generated by the heater.
Vulcan heater wiring diagram
(also shown under the metal cover of the fan switch)


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