Troubleshooting Automatic 2-channel Multiplexers with Built-in Diagnostic Tools
Problem
Possible solution
Multiplexer will not power ON.
Check the silver tag on the back of the multiplexer to determine the correct supply voltage for that model. Using a volt meter, test across the terminals marked supply voltage + and - for the correct power.
Multiplexer will not power ON. (Part 2)
If the correct power is present on the + and - terminals, inspect the sides of the housing for discoloration. Is the multiplexer hot or producing a strong odor? If so, the multiplexer may be damaged due to voltage spike (ie: lightning) and should be replaced.
Output status light remains illuminated constantly.
Verify that the correct transmitter and receiver combination are aligned with one another. (ie: the transmitter from channel 1 is matched with the receiver from channel 1) The transmitter or receiver photo eye wires may be short or open. This problem may occur anywhere between the photo eye body and the multiplexer socket. Check all splices and terminal strips for incorrect connections. If the wires are not protected by conduit in any area, check the outer sheath of the cable to see if it is brittle. If any problem areas are found in the wires, cut and splice them. Solder the connection and protect it from moisture. If lengths of the wire need to be replaced, use at least .22 gauge conductors. If no problem is found in the transmitter wires, the problem may be the multiplexer socket. Replace any defective parts.
Output Status LED intermittently flickers
Since the problem is intermittent, it may be challenging to diagnose the problem. Clean the face of each photo eye with a mild non-abrasive detergent. Align the photo eyes using the "string method" of stretching a string or wire between the photo eyes so that the string passes by the eye in parallel. If both photo eyes are parallel to the string, the alignment should be correct. Check for cracks or deep scratches in the face of the photo eye. Water intrusion through a crack could damage the photo eye circuitry.
Output Status LED intermittently flickers. (Part 2)
The transmit level adjustment of the multiplexer may be set too low for the application. Switch the high/low DIPswitch setting to "high" for the channel that is experiencing the problem (See diagram printed on the side of the multiplexer) Look closely at the receiver photoeye while the problem is occuring. If the receiver is mounted in direct sunlight, this may cause intermittent false signals. Verify that terminal 3 is connected to Earth ground. If either photo eye appears damaged replace it immediately.
Output Status LED will not turn ON.
The transmit level adjustment of the multiplexer may be set too high for the application. Switch the high/low DIPswitch setting to "low" for the channel that is experiencing the problem (See diagram printed on the side of the multiplexer) Verify that terminal 3 is connected to Earth ground. If either photo eye appears damaged replace it immediately.
Multiplexer responds the opposite of its expected operation
If the multiplexer outputs when it shouldn't and doesn't output when it should, the problem may be the setting of the "switching behavior." To correct this, adjust the DIPswitch for the light/dark setting to the opposite setting (Whichever corresponds to the channel that seems to be functioning incorrectly.) The "switching behavior" or "Light/Dark" setting of the multiplexer controls when the multiplexer activates the output, either when the receiver sees light from the transmitter (light switching) or when it doesn't (dark switching)
