Landcal Blackbody Source
Type R1200P
User Guide
Page 14
Load terminals (2)
Logic signal terminals (2)
Solid state relay
MOV (if fitted)
Fig. 4 Solid state relay connections
1) Disconnect the furnace from the electrical supply.
2) Remove the rear panel from the furnace or control cabinet and locate
the solid state relay(s), removing any other panels necessary to give
reasonable access to the relay(s).
3) Disconnect the four or five wires, noting their numbers and positions.
4) Remove the faulty relay and replace it with a new one, noting which way
round to fit it.
Original relays are fitted with a thin layer of ‘off-white’ paste to give good
heat transfer to the aluminium sheet. New relays are supplied with a
heatsink 'pad'. All remnants of the old heatsink paste must be removed.
The thin white heatsink pad must be fitted between the solid state relay
and the plate to which it is mounted.
5) Tighten the two fixing screws.
6) Refit the wires as noted in step 3. If the replacement solid state relay is
supplied with a metal oxide varistor (MOV) it must be connected between
the load terminals as shown in Fig. 12. It is not polarity dependent.
The MOV protects the SSR from short periods of excess voltage. If the
replacement SSR is supplied without an MOV this is because the MOV is
built-in on later versions.
7) Replace the panels.
8) Reconnect the furnace to the electrical supply.
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8.3 Replacing the Solid State Relays
