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Author Topic:   Plug-compatibility between Lowrance HDS and older unit
tedious posted 06-01-2011 06:23 PM ET (US)   Profile for tedious   Send Email to tedious  
I have been using a Lowrance LMS332C Fishfinder / Chartplotter for 6 years, and it has just started acting up. The LMS332C has an external GPS module, and the display unit currently is intermittently complaining that it can't find the GPS signal. Power is correctly applied to both the display unit and module pins on the power / data connector, and the connector itself looks good.

Since a replacement external GPS module is quite expensive, I am thinking that it might make sense to just get an HDS5, which has an internal GPS module. Does anyone know if the Power / Data connector from the LMS will plug right into the new HDS? I know that the transducer will plug right in, and I don't care about the networking as we are not using it.

Thanks for any information you have!


jimh posted 06-01-2011 07:50 PM ET (US)     Profile for jimh  Send Email to jimh     
When installing a new HDS device, I recommend you use the power and data cord supplied with the device in lieu of trying to re-use a power and data cord that was designed for another, older device.
tedious posted 06-02-2011 08:46 AM ET (US)     Profile for tedious  Send Email to tedious     
I agree with you Jim, in general - but given the situation with this particular boat (a little older, no electronics other than GPS / fishfinder, no network) a plug-in solution is more appealing than rewiring. If the boat was in my driveway, rewiring would be less of a bother, but it's 200 miles away and I want to be using it on weekends, not working on it.

I do have an HDS7 on my 15, and I can check the plug there, but I just thought someone might know the answer.


jimh posted 06-02-2011 09:30 AM ET (US)     Profile for jimh  Send Email to jimh     
Tim--My recommendation is based on the notion that while the connectors appear to be compatible there may be difference in the actual wiring of the connectors. It was reported that the method of powering the device and the attached NMEA-2000 network devices may have been changed in the HDS models compared to some early Lowrance devices which had a NMEA-2000 interface. I don't know the details of the differences, so I cannot explain it further. However, an instance where someone used the older connector to power an HDS device resulted in a failure of some attached network devices to operate properly.
tedious posted 06-21-2011 08:52 PM ET (US)     Profile for tedious  Send Email to tedious     
For reference, the power and transducer connections from our old LMS-332C worked perfectly with the HDS-7. There may be or may not be networking [problems] or other [problems], but we don't use those, so I don't know. I did check the power pins to make sure they were the same before I plugged in.--Tim
SJUAE posted 06-22-2011 03:17 PM ET (US)     Profile for SJUAE  Send Email to SJUAE     
Here is an old picture I did some time back that may help


jimh posted 06-22-2011 09:41 PM ET (US)     Profile for jimh  Send Email to jimh     
My recommendation to use the new connector was based on two foundations:

--newer is better, well, at least you hope that is the case; and,

--a single report from another user who described a problem that appeared to be cured when he changed to the new connector instead of the old connector.

On careful review of the pin diagram that Steve has shown, it looks to me like there are only two power pins in the POWER/DATA plug. The other contacts in the POWER/DATA connector appear to be for the NMEA serial data and for a "wake-up" circuit. There are six contacts. The wake-up circuit is one of the contacts. This leaves five for the serial data. There are two contacts for inputs, two for outputs, and one for shield. This seems to use up all the pins. I don't see how there could be much variation in the power pin wiring. The other user's report of a problem associated with using the old connector may not have been entirely accurate. However, it is not a bad idea to use a new connector with the new unit, if for no other reason than to get a closer match and better mating.

I find that on standardized connectors, such as IEC power connector that is typical for 120-VAC power, one brand of cord does not fit as well into another brand's receptacle. I like to keep the cords matched to the connectors when possible. Some of my co-workers think I am a bit obsessive about this. Hah! What do they know?

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