Batboard

I have just acquired a GM1280 which is the Euro version of the CDM but the front head has a larger "2 line" LCD and there is a full keypad - you need to use an external speaker as there is no speaker built into the head. I don't think there is a USA CDM equivalent of the GM1280 but the main body is identical.

There is power getting to the head and the radio powers up OK but the LCD is completely dead.

Any ideas why the LCD is dead? Is LCD failure a common problem with CDM's?

I assume the flex cable from the body is correctly fitted as the radio does power up from the front knob and various LED's light up on the head.

Thanks

The only time I've seen the LCD dead in a CDM is if it was physically broken, and even then they usually still work to some degree.
One thing that can make you have no display is if it's not seated on the contacts, take the head apart and make sure someone didn't steal the rubber contact strips and that everything is seated properly.
There's a fuse that provides FLT_A+ (Filtered A+) to the head, but if I'm pretty sure that also powers the LEDs, so it's probably not that.

Thanks.

Any idea how the LCD is held in place on the PCB. Does it just "rest" on PCB contacts/pads with the rubber contact strip (elastomer?) placed between the LCD and PCB with it all being held in place using screws or clips?

3 minutes and a small flathead screwdriver later and you would have already found out... and likely fixed your problem, too! Do it yourself!

Don't you need a special tool to remove the head without causing any damage to the plastic?

May be I'm too cautious but I like to work out any potential issues before I dive in!!

Thankfully there are many helpful people on this forum who are willing to share their expertise and experience.

nothing more than a thin piece of plastic to pry the head off around the top and bottom. Very simple. I suggest against a screwdriver (though you could use one IF YOU ARE CAREFUL), as you'll probably mar the plastic.

Assuming it's similar to the CDM radios.... there's a plastic housing that contains the glass LCD and the rubber contact strips. That sits in the control head housing and the circuit board goes in on top of it and just snaps into place, no screws. Contact between the circuit board and display contacts is maintained by pressure, and the circuit boards tend to pop out if you're not careful when you push the head onto the radio body.

The tool to take the head off is just a wide plastic blade. The control head housing has two parts, usually you'll just take off the front part, but if you also take off the rear part and put the head together before snapping it back onto the radio body it's easier to keep the circuit board seated properly.
If you really want to get the tool you might check with a local Motorola dealer, there's one in every remote head kit so they tend to pile up after a while. You might be able to get one or two just for the asking.

Many thanks for all the helpful advice - its much appreciated.

The good news is that the LCD is working.

The bad news is that the reason why it did not work is that the "retaining bar" on the socket for the LCD module flex cable had broken off.

Maybe the Euro GM1280 is a bit different from the CDM. The LCD is connected to the control head PCB via a small flex cable. The flex cable socket on the LCD module is missing its light brown retaining bar so the flex cable does not stay in the socket. I found that if I gently but firmly press down on the flex so that it makes good contact with the socket, the LCD operates perfect.

Apart from replacing the entire LCD module or replacing the flex socket on the LCD module (difficult?), are there any other fixes which will hold the flex in place? I thought about just using some sellotape over the flex and a thin piece of cardboard down the front of the flex to wedge it into the socket and stop it coming out???

Any ideas?

Yes, that is certainly different than the CDM series.

Hard to say what might work to hold the cable in without seeing it. I suppose you'd have to keep pressure on the cable without putting too much pressure on the LCD itself.

I know exactly what you are referring to. That's going to be tricky.

Perhaps a small piece of plastic wedged in there, and then tape over that?

Thanks for the ideas.

I also thought of using a thin stiff strip of plastic packaging material - like what's used to package an SD card - and then use some double sided sticky tape on both sides of the plastic strip - so one side of the plastic strip is stuck to the flex cable and the other to the inside of the flex socket - so the flex is both wedged and stuck.

g8tzl2004 wrote:Thanks for the ideas.

I also thought of using a thin stiff strip of plastic packaging material - like what's used to package an SD card - and then use some double sided sticky tape on both sides of the plastic strip - so one side of the plastic strip is stuck to the flex cable and the other to the inside of the flex socket - so the flex is both wedged and stuck.

Sounds reasonable to me! If worse comes to worse, the socket CAN be replaced by someone competent with SMD soldering.