Strange problems associated with the timing between the multiplexer and VCR are sometimes traced to both devices writing in the same area of the vertical blanking interval. This can sometimes be corrected by turning off the time/date on the VCR. For general problems, perform the following check list:

1. Make sure that multiplexer VCR out is connected the VCR video input. Make sure that the multiplexer VCR in is connected to the VCR video output.
2. If you record from the monitor output BNC, you will record what is viewed on the monitor. You will not be able to decode individual cameras, or, change the video display on playback.
3. Once a tape has been recorded, it will playback whatever is recorded on it. If you discover and correct a problem with the BNC connections, make a new tape and test again (the old one will still be bad.)
4. Set the multiplexer VCR record time to match the requirements of the VCR. For time lapse VCRs, set the times the same (ex. 24 hr. mux and 24 hr. VCR). This is the "don't have to think about it" mode. If you know the field delay of the VCR, set the mux speed accordingly (one less than the field delay).
5. If you don't know the VCR field delay, you can experiment for faster results. Field delays typically range from 13 to 26 in 24 hour mode. Many newer models are 13. Try the multiplexer in 12 hour mode first. Record a few minutes of tape. Play it back in the 4x4 mode. Alternately press the live and tape buttons and observe the results. The mux decodes and displays the images one camera at a time, until all camera locations are displayed. With activity detection disabled, this should take about 3 to 4 seconds for 16 cameras (actually 3.2 seconds). Remember that activity detection causes moving images to update more often than still images. A single still image may take some time to update. Either turn off activity detection, or, just be aware of its impact on the test. If some cameras never seem to update, it is probably a timing problem. Try another hours setting between 12 and 24 in the multiplexer menu and do the test again (don't forget to rerecord the tape). You are ultimately looking for a smooth update of all the cameras with more updates of the active cameras than the still cameras.
6. If you connected the multiplexer alarm output signal to the VCR alarm input, set the desired alarm record speed in the multiplexer menu. This is typically 2 hour mode (one hour mode with the newer multiplexers).
7. If you are using a 24 hour "real-time" recorder, remember that they typically record 20 updates per second. Set the mux to 2 hour mode to accommodate this application. The one hour mode, (available on the new design - 30 updates per second,) will cause more harm than good. No alarm connection is necessary as the VCR is already going as fast as it can.

Monitor Problems: Check the "Lookout" section for a quick review of monitor issues.

Monitor issues are limited to how does it look? Is the picture all there and does what is there look good? Typical things to look for are:

1. Time and Date is missing. This could be because it is turned off on the multiplexer. Holding in the function button while pressing the right arrow button, toggles the time/date on/off.
2. If the time/date is still missing... It may be off the top of the screen, or, partially obscured because the display is over scanned. This is typical with televisions used as monitors.
3. Part of the camera titling is off the left edge of the screen. This is related to over scanning mentioned in #2 (see the "lookout" section for details). There are ten spaces available for the camera titling. If the first couple of characters run off the end of the screen, enter spaces as the first characters. You can abbreviate, or, use a real monitor.
4. Too bright? Too dark? Some cameras in multi-screen displays are too bright, or, too dark? Don't overlook the obvious. Adjust the monitor controls for brightness and contrast. Other than that, you probably have a termination problem. Some images to bright/dark? Probably a termination problem on a single camera, or, group of cameras.
5. Black and white instead color? Check the monitor adjustments. Some have a switch to turn off the color, as well as, the normal color adjustments. If you are playing back a tape, was it recorded using a color multiplexer, or, black and white?
6. Monitor display jitters/unstable. If you have monitors side by side and one has the video source removed, the other will waver. Turn off the power to the other monitor to check.

Camera Problems: Check the "Lookout" section for more information.
We need a one volt peak to peak composite video signal with no dc offset. Typical things to look for are:

1. Bad pictures. This can be caused by a lot of simple things. Is the camera lens focused? Can it see out of the housing? (Dirty window on housing, condensation on housing/lens.) Dirty monitor. Dirty covering over monitor screen.
2. Bad cables. Intermittent picture? Either most of the time, or, when it rains? Avoid any unnecessary connectors which might be exposed to the weather.
3. Bad termination. Remember, a straight coax from the camera, terminated at the last device.
4. Video loss. Could be caused by bad connections which disengage when someone, or the wind, moves a cable. Does that video signal stop off anywhere else before it reaches the multiplexer? Is someone else switching, or, disconnecting the cameras? Is someone turning off the power to the camera power supply?
5. Distorted pictures. Monitors are more tolerant of low video signals than digitizing devices like multiplexers. Just because the camera looks good connected directly to a monitor and bad through a multiplexer, it doesn't necessarily mean the multiplexer is defective, although, it is an obvious test. Do all the cameras look bad in the multi display, or, just some of them? Long cable runs may require amplification. 800 feet is the typical max distance for RG59 cable. Use good cables and make sure you are really getting a good signal through the system.

Power Supply Problems: The wall hung power supply provided with the multiplexer is extremely important. This is not the same supply which is readily available at any retail outlet. It provides 1.5 amps of current. Problems occur in the field when the wrong power supply is used. A supply which provides less than 1.5 amps, may work for a while, then overheat and fail. Worse yet, it may work again, for a short time, after it is allowed to cool. The end result is a continuing frustrating problem. Many multiplexers are returned for repair without the power supply, found to be good, then reinstalled using the bad supply. If you have the slightest doubt, replace the power supply.

The power supply has a center positive connection. The inside pin of the connector is +12 volts dc, the outside area is ground. Occasionally, a center negative supply is encountered in the field. It is unfortunate that so many different types of power supplies use the same type of connector. Some even give you the option to install the plug housing, or switch a switch, to provide either center positive, or, center negative. The result can be negative for multiplexers.

What happens? If you install a center negative supply on a duplex multiplexer, it will not work. It does nothing. No lights, no bells, no whistles. The thermistor fuse shuts down. When you figure out that you used the wrong supply and use the right one, everything is fine. You're back in business. If you install the same center negative supply on a new style simplex multiplexer, the fuse blows. Again nothing happens. When you figure out that you used the wrong supply, the fuse is still blown and must be replaced before normal operation is restored. This is difficult as the fuse is soldered in place and is of surface mount design. We are evaluating a return to the thermistor design. Meanwhile, be careful.