Carbolite VST Series - Manual (Page 9)

HST, VST
MF13 – 3.40
9
5.5 Thermocouple Replacement
The coverings and guards which must be removed to gain access to the thermocouple depend on
the model, and any mounting options or fittings. Study the furnace layout and consult Carbolite if
in doubt.
Disconnect the furnace from the supply, and remove covers and guards as necessary.
Make a note of the thermocouple connections. The negative leg of the thermocouple is marked
blue. Compensating cable colour codings are:
negative positive (type N)
white pink
Disconnect the thermocouple from its terminal block.
Withdraw the thermocouple from its sheath (the narrow-bore built-in tube) and remove any broken
bits of thermocouple.
Bend the new thermocouple carefully to match the shape of the original (working from the
terminal end). Should the length differ from that of the original this is usually not important
provided that the thermocouple tip is within a tube diameter's distance from the furnace centre; for
models with an even number of element modules, the tip should be a quarter to a third of one
element’s length from the furnace centre.
Insert the new thermocouple into position, restoring any removed porcelain spacers, and ensuring
correct polarity.
Re-assemble the furnace.
5.6 Fuse Replacement
Fuses are marked on the circuit diagram (section 7.0) with type codes, e.g. F1, F2. A list of the
correct fuses is given in section 8.1. Depending on model and voltage, the different fuse types may
or may not be fitted.
If any fuse has failed, it is advisable for an electrician to check the internal circuits.
Replace any failed fuses with the correct type. For safety reasons do not fit larger capacity fuses
without first consulting Carbolite.
The fuses are near the cable entry point, and access is by removal of the back panel of the base or
control box.