XG-100M brick umm...bricked

[k8zdr]

I have a XG-100M brick that seems to have become "bricked". I was checking the versions on it in RPM by clicking the "Read Ver" button when something went sideways and the radio would not reset at the end of the process. It now shows the "Lost MRU" message on the control head, with occasional changes to "No MRU". Attempts to read or write to the radio in RPM result in "could not initialize radio" messages. Connecting a serial cable to the radio doesn't show any messages on the terminal when powering on.

I've ruled out everything else in my setup, because swapping in a different brick results in everything working as it should.

Does anyone have any ideas on how to bring this thing back to life, or if it can be brought back to life? Any recommended places to look inside the brick for possible failure of the CAN interface or something else?

 

[nikronzo]

The CAN interface might be bad, switch the setup from remote to dash mount and see if the behavior persists. A inhibited radio would not show Lost MRU, it just wouldnt power.
Also hook up a db9 cable to the brick and see if there is serial output in a emulator, you have to set the baud rate to 119200 or something iirc.

 

[k8zdr]

There are no serial messages showing up in a terminal. The board shows a flashing yellow light in the area where the CAN connection hooks up, but no other lights come on inside the unit. The flashing light goes off after ~10 seconds when the head is powered off.

I think I'm lacking an adapter to create a dash mount setup, there's a ribbon cable inside the front, but I don't have any heads that will connect to it.

 

[nikronzo]

You can make a remote mount a dash mount using the ribbon cable from the CH721 control head interface back. But you need to convert the CH721 to dash configuration using hyperterminal. There are posts on here on how to do that.

 

[merlin]

I think I'm lacking an adapter to create a dash mount setup, there's a ribbon cable inside the front, but I don't have any heads that will connect to it.

Before you change to dash mount, you need to configure the 721 independantly with Hyperterminal.
After that is done correctly, separate the front/rear housing with the ribbon in the front.
That will connect to the connector on the front of the MRU. 2 screws and should be ready to go.
One thing I see here not good is when the MRU is powered up. Meaning disconect from power, reconnect and power on. you should get an RS232 data stream on the DB9 connector. the protocol is 119200-N-8-1.
Here are some of my notes:

 

[k8zdr]

I've reprogrammed a spare CH721 as a front mount, and separated the housings. There are two 16-pin ribbon connectors on the CH721 display section, one labeled J9, and one labeled J10. Which one should be connected to the MRU ribbon connector?

I agree that the lack of serial data output from the MRU is not a good sign. My good brick sends out boot info over the DB9 connection when it powers up.

 

[Forts]

on the DB9 connector. the protocol is 119200-N-8-1.

115200. 119200 isn't a valid baud rate.

 

[merlin]

Hmm, I get good connection with 119200. 115200 I have to specify a custom baud rate.

4.75 MB file on MEGA

mega.nz

There are two 16-pin ribbon connectors on the CH721 display section, one labeled J9, and one labeled J10. Which one should be connected to the MRU ribbon connector?

You got me. I only recall one ribbon that goes to the ribbon connector on the MRU. I linked the manual above.
Page 51 breaks it down.

 

[merlin]

119200 isn't a valid baud rate.

yea, a typo the baud rate is 19200.

 

[k8zdr]

Hmm, I get good connection with 119200. 115200 I have to specify a custom baud rate.

4.75 MB file on MEGA

mega.nz

You got me. I only recall one ribbon that goes to the ribbon connector on the MRU. I linked the manual above.
Page 51 breaks it down.

Thanks for the link. I think I guessed right, because the display came on when connected via the ribbon cable. However, I still got the same "Lost MRU" indication. I am starting to think based on the lack of serial data output on power-up compared to my good unit that this one is dead.

 

[merlin]

Thanks for the link. I think I guessed right, because the display came on when connected via the ribbon cable. However, I still got the same "Lost MRU" indication. I am starting to think based on the lack of serial data output on power-up compared to my good unit that this one is dead.

First thing I would try is switching off the power, then shut down your supply. Wait a good 30 seconds and power everything back up.
A glitch in the power can cause issues so you need a common ground and common B+. Strongly suggest a 13.6 volt @ 30 amp supply.
That has fixed a couple of 100Ms I have had on the bench. A firmware problem may show burnapp that won't clear.
Still no RS232 port comm, may be a hardware failure. Has to do with the complex CAN/Serial port switching. Not good.