Furuno 841 and 841 mark 2 scanner compatibility.

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We have an 841 with optional display in pilot house, on passage main display went dark and hdg sig missing came up on remote display with no signal. Pressing power switch on main display resulted in just a flash no start up. Disconnect cable to main display it lights up fine. Further testing and plug 801 on md board in scanner appears to be where issue begins. With this unplugged, display will light up, plug it in and display goes dark again and so scanner does not power up. The md board is not a board to replace in remote Tongan anchorage. Option and question as follows. We can aquire a used 801 mk2 scanner and can not determine if it is a plug and play swap possibility. This would resolve it and we could be up and running quickly. To change cable at this point is not an option due to having to remove radar arch etc,,,not happening inTonga. Q, is the cable and scanner a match from 841 to 841 Mk 2 as such can we plug and play? Many thanks in advance for any input. Sort of stuck here in paradise.
 
The 841 is over 20 years old. You might look on the used market and find a used dome. Furuno USA doesn't stock or sell used product.

You might want to check your display unit to see if it allows you to run an 841mk2 scanner. The 841 is a 32v tuned unit and the 841mk2 is a 12v tuned unit. They are NOT considered compatible unless your display has the right SPU board and firmware to support the newer 841Mk2 scanner. Your display would need to have SPU-9180 main board and NOT the SPU-9180D. If you do you could call tech support on help in switching the display to support the 841MK2. It might be best to stick with the same scanner you have now.

Being that you are at a remote location with an old radar, It might be worth considering going with a newer modern unit. You might save a little now by piecing things together an old radar but it might not be worth it in the long run.
 
Hello from Tonga Johnny!
Many thanks for the response. I should be clearer with info. We can acquire the 841 scanner and display together and do the swap out here but the challenge out here is the cable run as I can not get to it without arch removal requiring a crane or forklift and some destructive results. Just not in the cards. So wonder if we can utilize existing cable and simply change display and scanner set together. This would be a good temporary solution. And of course to add complexity we do have and we do need the FMD 811 optional display which we hope would also work attached to the 841 mark2 main display. Yes, for certain a modern unit is next up and we would simply just do it now but we have the same major challenge with the cable run so is something that is Not happening until we are back in the first world unfortunately. So we wanted to try and extend our cruising safely until then. Our original 841 schematic and owners manual lists the SPU as 9180 but can we assume that is what is in there or can I identify it by looking inside the display?

After all that ramble, here are the main questions,
If we have the 841 mark 2 display and scanner will 841 cable work?
Will 811 optional display work with 841 mark 2 display ? The manual says it should.

Thanks again for the assistance, we really do appreciate it.
 
Confirmed existing display shows SPU 9180. Assume this is a good sign and we could swap out the scanner. If required it is nonissue to swap to mark 2 display as well but need to understand if it will operate the remote 811. If so we are in good shape save shipping all that good stuff from east coast US to Tonga. Next challenge to overcome. If you have time to confirm we would be very grateful. Many thanks again

Russ
 
The 841Mk2 would have the same slave connector inside the unit to support your exiting slave radar (FMD811 in your case).

You can use the same cable for the 841MK2 that you had from your 841.

It might be best to swap both scanner and display so you know it works. You can always then attempt to use your old display with the MK2 scanner.

If you decide to try your existing display, Set the radar range to 0.5 nm. Next while pressing and holding down the [HM OFF] key, press the [OFF CENTER] key five
times. Beep sounds to inform you that the model designation has been changed.
Open the SELF TEST menu to see the model name selected. It should now show 841 Mk-2.

Do not attempt to transmit the radar until you know the radar model has been changed.
 
Thank you very much Johnny. We will organize getting the mark 2 stuff here and advise how we do with install.
You have been very helpful!
 
Hello again Johnny. Just to confirm we have the info on the mark 2 scanner now model RSB0071. RO76-3540 versus our existing 841 at RSB0055 and RO67-1157. Before shipping at a ridiculous cost we just need to be certain and if you would not mind one more comment to confirm as per above we would be very grateful. We would switch both scanner and main display to be safe.
Again many thanks in advance.
 
The M841 uses RSB0055-049. (last three digits is what we call the RTR number and is normally shown as the last three digits of the FCCid#) This radar is a 32v tuned linear radar. The other number you listed (RO67-1157) is just a serial number and not really useful in the discussions.

The M841MK2 uses the RSB0071-058. This unit is a 12v tuned linear radar.

Both radars have the same number of conductors and pin out for the scanner cable, so the cable can be used with either system.
 
Once again thanks for the thorough response and complete explanation. You do a great job and we very much appreciate it. Will advise how we make out once complete.

Have a good weekend
Cheers from Tomga
 
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