CH-721 question

[marcotor]

So I took the jump into Harris land, and am happy I did. The question I have is the CH-721 Sys head that came with my XG-100M upon start displays Warning! Lost MRU, as tho the brick is dead/not connected. It hesitates for a moment, then displays normally. This does not happen on the 721 Scan head (which has other issues), when it is attached the radio comes on normally. I have confirmed via terminal that both heads are configured for remote mount. FW is R06K07 on the brick, and 3.10(?) on the head. Also confirmed the CAN cable is good as it does not throw any errors when connected to the 100 in the car. Anyone have ideas? thanks!

 

[nikronzo]

All I can think of off the top of my head is the brick isn't getting power at the same time as the control head. LOST MRU only really shows up for 3 reasons

• No Brick Power
• CAN Cable disconnect/fault
• CAN Terminator Missing/Loose

Do you have a CAN terminator in both the head and brick or just the brick?

 

[prcguy]

You might also check firmware revisions.

 

[merlin]

I can't add much but 'lost MRU' the head and radio are not talking to each other.
You can update the CH-721 with the latest firmware and check the head ID string for proper configuration.
Any open CAN bus connections must be terminated.
Good cable, both head and radio powered correctly, a persistent "LOST MRU" can mean the radio has been bricked. Lets hope that is not the case.
But I think the 721 is not set up correctly, especially if the scan head works at all.
Cheers

 

[redbeard]

Probably the old head fw. 7.17 is the latest.

 

[marcotor]

Good cable, both head and radio powered correctly, a persistent "LOST MRU" can mean the radio has been bricked. Lets hope that is not the case.
But I think the 721 is not set up correctly, especially if the scan head works at all.
Cheers

Well, no. The radio is NOT bricked, as I stated. I would think a "brick" wouldn't work with a different head. And I did confirm the proper string was in all the heads as I wrote in my post. After powering on, get the normal Booting... then WARNING! Lost MRU is on the screen for perhaps 4 seconds, then proceeds as nothing happened. All buttons/volume/channel knobs work, and the radio performs as expected (and excellently, I might add).

Edit: Visual Aid here - CH 721 Odd Boot - YouTube

Thanks to those that offered assistance!

 

[prcguy]

Well, no. The radio is NOT bricked, as I stated. I would think a "brick" wouldn't work with a different head. And I did confirm the proper string was in all the heads as I wrote in my post. After powering on, get the normal Booting... then WARNING! Lost MRU is on the screen for perhaps 4 seconds, then proceeds as nothing happened. All buttons/volume/channel knobs work, and the radio performs as expected (and excellently, I might add).

Edit: Visual Aid here - CH 721 Odd Boot - YouTube

Thanks to those that offered assistance!

I recently mixed four XG100M bricks with random eBay heads including M/A-COM and noticed the same brief msg on some but I also upgraded all firmware shortly after and have not seen the problem since.

 

[marcotor]

I recently mixed four XG100M bricks with random eBay heads including M/A-COM and noticed the same brief msg on some but I also upgraded all firmware shortly after and have not seen the problem since.

Thanks, given your SoCal connections, I have a feeling we know some of the same people.
The FW update did the trick, altho coming from the /\/\ side, it was a bit of a white knuckle. I am 100% satisfied
with these radios, their features, and given the current state of pricing would heartily recommend to anyone looking
for a multi-band solution.

 

[EDACSMT1]

Check to make sure the termination "bullet" is on the head and radio.
Lost MRU means the head cannot talk to the Main Radio Unit.
If that doesn't fix it, the diodes are probably blown in the radio or control head.

 

[prcguy]

Check to make sure the termination "bullet" is on the head and radio.
Lost MRU means the head cannot talk to the Main Radio Unit.
If that doesn't fix it, the diodes are probably blown in the radio or control head.

What diodes?

 

[redbeard]

What diodes?

It's the amateur electrician version of 'it's a bad ground' i.e. no fscking clue