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DSM250 - No Data Source or DSM Connection Lost reported

Most DSM related issues, where No Data Source or DSM Connection Lost is reported, are due to installation issues and/or insufficient power (i.e. current) being supplied to the DSM. From an installation standpoint, there are three issues that must be addressed when installing the DSM:

- Unmodified hsb cable has been exclusively installed.
- A hsb2 inline termination plug is present within both the hsb2 port of the DSM250 as well as within the display's hsb2 port ... if the product's hsb2 port is black in color, then you are actually looking at the male side of a hsb2 inline termination plug
- The hsb cable is in good condition and have proper strain relief
Excess hsb cable has been loosely coiled to comply with the recommended minimum bend radius (3") and secured to a bulkhead. Subjecting communications cables to a bend radius which is less than the minimum stated may adversely affect communications and permanently damage the cable.
- The marine electronics must be powered from an isolated power source
- Power Cable failure ... recommend flexing the DSM's power cable within 6-8" of the cable's plug while the DSM is powered. Should the DSM reboot when the cable is flexed, then it would be recommended that the DSM be tested with another power cable.
- The power cable length for the DSM must be kept as short as possible. Should it become necessary to extend the DSM's power cable, cable of the appropriate gauge for the round trip run should be added. Alternatively, install the DSM with the supplied power cable and then install a communication cable of longer length.
- The DSM should be powered from a dedicated breaker or switch, permitting the DSM to be powered off when not in use. This will also permit the DSM to be restarted without affecting the state of the other marine electronics.

Where power related failures occur, it is not usually low voltage, but rather low current availability that causes the problem. One may think of voltage as water in a hose and current as the amount of pressure behind that water that makes it move when the nozzle is opened. Simply measuring 12 volts on a voltmeter at the DSM power cable's plug does not lead to much insight regarding how much current was available. For example, the available voltage from 8 D-cell batteries is 12VDC. However, these 8 D-cells cannot provide sufficient current to run one's electronics. In a typical day of fishing, one starts the boat's engines, runs the engines for a short time to while traveling to a fishing location, drifts or anchors for a while with the engines in neutral or off, starts the engines again to relocate to another fishing location (repeating this process perhaps several times throughout the day), and finally runs the engines for a short time while traveling home. During this process, the engine alternator, which may be rated for 50 amps (but only when running at a higher RPM) can not replenish the amount of current that has been drawn from the batteries throughout the course of the day. The output of the alternators on most boats at trolling speeds is generally much lower than at peak output. As such, we have a situation where engines are started often, drawing a great deal of current by themselves, coupled with the marine electronics running at all times causing the available current to be reduced throughout the day. Should one do a couple of trips over a weekend and then leave the boat without a full charge till next week, the problem compounds itself until finally, the battery amperage drops below the current threshold level required to sustain the electronics. The first signs of insufficient current are often blinking of the display's back light and intermittent or total malfunction of the DSM (which when searching draws 5-8 amps) causing the No Data Source or DSM Connection Lost message to be displayed.

From a trouble shooting perspective, inspect the installation to ensure that all of the above listed installation items have been addressed. Ensure that the batteries have been fully charged. Check the size of the wires supplying power to the marine electronics to ensure that they are no less than 12 gauge. Check the age of your electronics batteries and if the batteries are not sealed, check the water levels in them. Clean all the contacts and cable points and be sure that the connections are as tight as possible, then spray the terminals with a sealer designed to keep corrosion down. Have the batteries load tested as load testing will tell one how the batteries will perform when all equipment is powered on and functioning.

Power related problems occur most frequently on boats that are not plugged into shore power with an on-board battery charger between trips. Within 3 days of fishing, it is possible for the amperage of deep cycle 4-d batteries to drop low enough to cause the products to begin exhibiting the symptoms described earlier. One test that should be performed is to operate the equipment for the time specified while connected to shore power to determine whether the problem can be reproduced while connected to shore power. In so and should you address all of the above listed items, then it would appear that the DSM is beginning to fail. The DSM250 can no longer be serviced by Raymarine's Product Repair Center and compatible DSMs (i.e. the DSM30 and DSM300) are no longer being produced. Should the DSM have suffered a failure, then it would be recommended that you seek a replacement from the second hand market or consider a more comprehensive system upgrade.

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