Unit installation

60 OMRCPMICRO
2. Remove the MCB Power In terminal strip connector and check for 9 VAC between the terminals on the
plug corresponding to terminals 2 and 3 on the board (see MicroTech Schematics 1 and 2). Then check for
9 VAC between the terminals on the plug corresponding to terminals 1 and 3 on the board. Readings of 9-
12 VAC are acceptable.
If 9 VAC is present between both sets of terminals, go to step 3.
If 9 VAC is not present between both sets of terminals, check transformers T4 and T2 and all wiring
between the 115 VAC source and the Power In plug.
3. Remove power from the controller by opening circuit breaker CB1. Check the MCB power supply input
fuses (mounted adjacent to the power connector on the MCB) with an ohmmeter. A good fuse will have
negligible resistance through it (less than 2 ohms).
If either or both fuses are blown, replace them. Go to step 4.
If the fuses are intact, the MCB is defective.
4. Reconnect the Power In plug and disconnect all other connectors on the MCB. Cycle power to the
controller (close and then open CB1) and check the power fuses.
If both fuses are intact, go to step 5.
If either fuse blows, the MCB is defective.
5. Reconnect the keypad/display ribbon cable. Cycle power to the controller and check the power fuses.
If both fuses are intact, go to step 6.
If either fuse blows, check the keypad/display and the connecting ribbon cable for shorts. Either one may
be defective.
6. Reconnect the analog input ribbon cable. Cycle power to the controller and check the power fuses.
If both fuses are intact, go to step 7.
If either fuse blows, check the ADI board, the connecting ribbon cable, the leaving water sensor and the
optional package sensors (if present) for shorts. Any of these may be defective.
7. Reconnect the digital input cable. Cycle power to the controller and check the power fuses.
If both fuses are intact, go to step 8.
If either fuse blows, check the ADI board, the connecting ribbon cable and the control circuit digital input
wiring for shorts. Any of these may be defective. To rule out problems with digital input wiring from the
control circuit components, disconnect wire 809 from terminal 25. This wire provides 25 VAC to the safety
and control circuit components. An alarm will occur when disconnect wire 809. If shorts occur in the
control circuit digital inputs, the wiring should be checked at the digital inputs. It may be necessary to
trace the wiring back to the control circuitry. When finished checking the power input from terminal 25,
reconnect wire 809 and clear alarm(s).
8. Reconnect the Aux/Out connector plug to the MCB. Disconnect the 5 VDC regulated power plug for the
transducers from the MCB. Cycle power to the controller and check the power fuses.
If both fuses are intact, go to step 9.
If either fuse blows, check the transducers and their wiring for shorts or scrapes. If a modem is present,
check its wiring and operation. If the 12 VDC unregulated signal from terminal #146 is being used, check
the wiring back to the controller Aux/Out connector. This power supply may be used to power the 4-20mA
reset signals for leaving water reset and/or demand limiting. Disconnecting the reset connections at
terminal #146 can rule out or isolate a power problem with these external signals.
9. Reconnect the digital output ribbon cable to the MCB. Cycle power to the controller and check the power
fuses.
If both fuses are intact, the problem may be indeterminate. Obtain factory service.
If either fuse blows, check the output board, the solid state relays and the connecting ribbon cable for
shorts. Any one may be defective. See below for testing the output board and solid state relays.