Icom M421 problems

[Birdseye]

Got 2 ICOM M421 radios and a Garmin 76 to feed them with position for the DSC.. But despite correct connections, the feed of position to the radios works intermittently, maybe once every 10 attempts at best.

Long exchange of e mails with Garmin who as usual were helpful, but apart from checking the connections and settings they could suggest nothing because my Garmin 76 happily feeds NMEA sentences both to my computer, to a Simrad RD 68 DSC radio and to a JRC radar. Doesnt seem to me that there can be much wrong with the Garmin given this background.

ICOM on the other hand were polite but unhelpful. They suggested that the problem might be too many NMEA sentences coming out of the Garmin, but if other makes can cope with this issue then so should ICOM. In the end they said "cant help" which I dont think is good enough customer service on 2 new radios. What use is DSC without a position feed? Are you really going to tap in the position whilst sinking?

Has anyone else had this problem with the M421? Has anybody got a helpful contact name at ICOM ?

 

[gandy]

Does it work with only one Icom connected?

Is the Garmin battery powered, or powered off the ship supply? I wonder if there's some issue with different references. Garmins normally use single NMEA+ output, with DC ground as the return. Icom has NMEA+ and NMEA- separate.

 

[Blue5]

Garmin 76 is a handheld, have you looked at possibility of needing an external aerial?
I also have an Icom421 but we have connected to a fixed Garmin 152 for DSC purposes with no problem and I keep a Garmin 76 on the deck as back up.

 

[duncan]

[ QUOTE ]
ICOM on the other hand were polite but unhelpful. They suggested that the problem might be too many NMEA sentences coming out of the Garmin, but if other makes can cope with this issue then so should ICOM. In the end they said "cant help" which I dont think is good enough customer service on 2 new radios.

[/ QUOTE ]

well as the recomended max devices is 3 this would seem reasoanable and if the 76 is running on batteries even more so!

I assume you have connected the NMEA- from the Icom direct to the -ve power lead on the Garmin lead - it really seems to make a difference.

I ran a very similar set up but elected to remove the JRC from the circuit when adding the ICOM because of advice (not from ICOM but from here) that more than 3 was not wise. No problems with either 215 or 225 units feeding the 421 since installation.

Obviously easier to prove this isn't you issue than prove it is.

 

[FAITIRA]

Try "gpsbitz" they are very helpful.

 

[Birdseye]

Sorry but I dont seem to have explained myself well.

The Garmin 76 worked well with an RD68 and a JRC radio connected on the boat. It worked well with the computer connected at home. But it wouldnt work with either of the ICOM radios connected individually - never tried the 2 together.

You have the 76 as a back up. Have you tried it with the ICOM? Does it work? Would be very helpful if I knew since I would then know whether these 2 sets are faulty or the problem is general to the ICOM radios. And have you adjutsed the other GPS so that only a few NMEA sentences were given out?

 

[Birdseye]

[ QUOTE ]
Does it work with only one Icom connected?

[/ QUOTE ]

Never tried with more than one connected.

[ QUOTE ]
Is the Garmin battery powered, or powered off the ship supply? I wonder if there's some issue with different references. Garmins normally use single NMEA+ output, with DC ground as the return. Icom has NMEA+ and NMEA- separate.

[/ QUOTE ]

The Garmin is battery powered whilts the radios are using ICOM supplied mains power sources. ( they are the ICOM supplied two radio set up for teaching the VHF licence) The NMEA connection uses the ICOM lead supplied with the radio and the Garmin lead with negatives connected together ad positives too as suggested by both Garmin and ICOM

What you suggest is interesting and makes me wonder. I will try earthing the NMEA negative to the ICOM power supply negative and see if that makes a difference.

 

[Blue5]

Sorry I have not tried the Garmin 76 with the 421.

The other possibility that came to mind was to check the correct interface was set on the 76, unfortunately all paperwork is on the boat but from memory default on the 76 is Garmin/Garmin and again from memory the 421 requires GPS to be set to NMEA.

Might be b***cks but worth a check

 

[Birdseye]

already done and yes it is the correct interface.