Motorola CDM1550 Randomly Shuts Off

[BlueDevil]

I have a Motorola CDM1550 that is intermittently and randomly failing. This radio is setup as a base station unit. It's primarily operating as a receiver and very rarely transmits. It is located in a server room with lots of other electronic equipment (computers, servers, amplifiers, etc...). The room is fairly warm but not hot. At first I thought that the power supply maybe over heating and failing. I have sinned switched out power supplies and it is still having issues. The radio seems to automatically reset and come back on. I don't know how many amps the radio is drawing while monitoring. I also don't know how warm it is getting. I don't have regular direct access to the radio. It is at a different location.

Any thoughts or suggestions?

 

[SteveC0625]

I have a Motorola CDM1550 that is intermittently and randomly failing. This radio is setup as a base station unit. It's primarily operating as a receiver and very rarely transmits. It is located in a server room with lots of other electronic equipment (computers, servers, amplifiers, etc...). The room is fairly warm but not hot. At first I thought that the power supply maybe over heating and failing. I have sinned switched out power supplies and it is still having issues. The radio seems to automatically reset and come back on. I don't know how many amps the radio is drawing while monitoring. I also don't know how warm it is getting. I don't have regular direct access to the radio. It is at a different location.

Any thoughts or suggestions?

Brandon,

Take a look at how it's programmed for Ignition Sense and how it's powered for the same. In most base station installs, we program the radio for ON/OFF and Ignition Sense, and we provide Pin #10 with +12vdc from the same source as the radio, i.e. the power supply. If your unit is set up that way, check out the Ignition Sense line all the way from source to the radio. It's possible that you've got an intermittent somewhere. If +12vdc comes from anywhere other than the same power supply as the radio, investigate that thoroughly. Loss of ignition sense would be my first guess.

 

[BlueDevil]

I will double check that!

 

[Thunderknight]

Could it be "randomly" failing when someone does use it for transmit?

When it resets and comes back on, does it just quickly power cycle, or does it stay off for a while and then come back?

Not to get too far off topic, but if the sever room is warm enough for you to consider overheat issues, then you have a bigger problem. That room needs to be cooled for the benefit of the other equipment in there too.

 

[R8000]

I have had CM300's turn off on their own when connected to external devices improperly. We used some to drive PA amplifiers in some buildings and every one of them had the same issue. Turns out, one of our old techs that used to work for us had one wire wrong on the 16 pin accessory connector. The radio would run for awhile, get warm then power cycle. After correcting the problem, they were fine.

This may not be your problem, but if you have it connected to a external device, check your connections. Could also be something where your CDM power supply is on one phase of AC power and your device on the other that's causing grief.

Good luck.

 

[BlueDevil]

I need to double check the pin outs I think. This CDM1550 is connected to a CPI Controller for remote deskset units that are used throughout the station. I don't think it is powering down during transmit. It doesn't seem to just power cycle either. It shuts down for a while. As I recall I have the ignition sense turned on and it wasn't recognizing when the power supply went from off to on I would still have to manually turn on the radio. Maybe that pinout is connected incorrectly. I am going to go check on it today and hopefully have some pictures so share.

 

[BlueDevil]

Here are the pictures of the current wiring interface between the CDM1550 and the CPI Controller.

 

[jim202]

I need to double check the pin outs I think. This CDM1550 is connected to a CPI Controller for remote deskset units that are used throughout the station. I don't think it is powering down during transmit. It doesn't seem to just power cycle either. It shuts down for a while. As I recall I have the ignition sense turned on and it wasn't recognizing when the power supply went from off to on I would still have to manually turn on the radio. Maybe that pinout is connected incorrectly. I am going to go check on it today and hopefully have some pictures so share.

Let me jump in here and ask a simple question. I may have missed it if I did, please humor me and answer it again. What is the amp capacity of the power supply that is running this radio? My reason for asking is if the current is marginal for what the transmitter pulls, if someone does key the radio and the supply is being pulled down by the transmitter, it could cause the radio to reset due to low voltage.

As has been already mentioned, there are a couple of ways to use the ignition sense. I like to put the sense line connected to the power supply voltage. This way when the power supply turns on, the radio will also turn on.

There is a very slight possibility that you have a high SWR problem with the antenna. When someone keys the radio, the RF is getting into it and causing it to reset. Simple way to throw this idea out is to put a watt meter on the antenna cable from the radio and measure both the forward and reflected power. If you see very little reflected power, your good to go. You can cross this off the list.

Other than these ideas, see if you can borrow another radio. Swap it out with the one you have and see what happens.

 

[BlueDevil]

Let me jump in here and ask a simple question. I may have missed it if I did, please humor me and answer it again. What is the amp capacity of the power supply that is running this radio? My reason for asking is if the current is marginal for what the transmitter pulls, if someone does key the radio and the supply is being pulled down by the transmitter, it could cause the radio to reset due to low voltage.



As has been already mentioned, there are a couple of ways to use the ignition sense. I like to put the sense line connected to the power supply voltage. This way when the power supply turns on, the radio will also turn on.



There is a very slight possibility that you have a high SWR problem with the antenna. When someone keys the radio, the RF is getting into it and causing it to reset. Simple way to throw this idea out is to put a watt meter on the antenna cable from the radio and measure both the forward and reflected power. If you see very little reflected power, your good to go. You can cross this off the list.



Other than these ideas, see if you can borrow another radio. Swap it out with the one you have and see what happens.

The Power Supply is a Astronaut RS-20A which is rated at 16A continuous and 20A surge.

 

[SteveC0625]

In your pic of the radio's accessory connector, there's no ignition sense wire in Pin #10. So your power supply and wiring to the radio should be thoroughly inspected first.

Where is the power supply getting it's 110vac? That source needs to be checked out as well. It would not be the first time that intermittent or even switched power was connected to a 24/7 power supply like this.

When you get this all solved, I would suggest you add an Ignition Sense to the wiring and drive it from the same power supply. Radio needs to be programmed for On/Off AND Ignition Sense.

If nothing else, you should have a log started of when the radio shuts down and when it restores. That should be compared to whatever else is going on in the station at the time.

 

[SteveC0625]

One more thing. In the first pic, you can see the edge of the main power connector and you can see the exposed contacts. That connector should be fully seated so that there's no space between the radio side and the cable side. Visible contacts suggests to me that there might be a wobbly connection. Basic wiring 101.

 

[BlueDevil]

I just got done adding the ignition sense wire.

I pushed in the main power connection wire so that it was properly seated into the radio. The radio is powered by an Astron-RS20A power supply which is plugged into a APC UPS/Battery Backup which is then plugged into the 120v wall outlet which is backed up by a generator. The power supply is producing 13.73 volts while the radio is on. The voltage drops to 13.71 when the radio is transmitting.

The radio was on and working when I just went to check on it. The warmest spot on it registered 85 degrees which was a little warmer than room temperature. I used the radio to transmit a couple times. It worked fine.

 

[BlueDevil]

Radio is still intermittently/randomly failing...

 

[mmckenna]

Radio is still intermittently/randomly failing...

Not sure if this was mentioned anywhere above...
I sold one of my old radios on e-Bay once (big mistake). It worked just fine when I sold it, but when the guy got it he claimed it would intermittently fail. He tried to get a refund due to me selling him a "known damaged" radio. After all the round and round it turned out that when he installed it he had done a sloppy job on the crimp connectors. Once he re-crimped them using the proper tool all the issues went away.

So, have you gone through and check each and ever connection? Not a visual inspection, but actually pull on each connection, make sure it's fully crimped/solder/screwed down? Sometimes it's a simple little issue like this that will knock things out.

Also, I run several CDM radios both at work and at home/mobile. I haven't had this issue with them, but I did have an issue with bad audio. I did some research and found there was a known issue with the screws that hold the top/bottom of the radio together coming loose and causing the issue I was having. Simply re-tourquing all the screws fixed the issue.

 

[mmckenna]

I'd also add:
Make sure everything is properly grounded. Looking at your tone remote, I don't see the ground point connected. I'd recommend grounding the tone remote ground pin and the body of the radio to a known good ground. Don't rely on the negative power lead providing a good ground connection through the power supply.

many years ago I had an old Yaesu 2 meter mobile mounted between the seats on my truck. I only had the antenna connection and the + & - connections. Occasionally the radio would power cycle of no apparent reason. Took me a while to figure out that when I got in the truck or slid around on the seat the static charge was resetting the processor and killing the radio. Once I installed a dedicated ground strap from the body of the radio to the seat frame the issue went away.
Again, relying on grounding through the power source or antenna jack isn't a good idea.

 

[RBMTS]

Humor us and take the APC battery backup out of the mix so that the power supply is connected directly into the wall outlet. I have seen some situations where power anomalies have caused APC units to switch to the battery backup momentarily. If this is happening to you then this might be the reason why the radio is shutting down.

Just something to consider so that you look at all possible considerations.

 

[BlueDevil]

I have tried taking the APC battery backup out of the mix but will try it again.

 

[BlueDevil]

I'd also add:
Make sure everything is properly grounded. Looking at your tone remote, I don't see the ground point connected. I'd recommend grounding the tone remote ground pin and the body of the radio to a known good ground. Don't rely on the negative power lead providing a good ground connection through the power supply.

many years ago I had an old Yaesu 2 meter mobile mounted between the seats on my truck. I only had the antenna connection and the + & - connections. Occasionally the radio would power cycle of no apparent reason. Took me a while to figure out that when I got in the truck or slid around on the seat the static charge was resetting the processor and killing the radio. Once I installed a dedicated ground strap from the body of the radio to the seat frame the issue went away.
Again, relying on grounding through the power source or antenna jack isn't a good idea.

Thanks! I will go through and check all the connections. There are only a few of them. Everything else is direct connection. Very few crimps and the like. I will also take a closer look at the grounding of all the components.

What is the best way to pull supplemental audio? Right now it appears that they are pulling audio off of the CPI Controller instead of directly out of the back of the radio. They are pulling audio to input into an amplifier for a speaker system throughout the facility.

 

[mmckenna]

Looks like they are already pulling the "flat RX audio" off the back of the radio via pin 11 and feeding that into the CPI box. Only other usable audio output off the 20 pin connector on the back of the radio is for the external speaker. Not a good choice for feeding an amplifier.

Looks like public address audio is tapped off pin 6 of the CPI box for feeding audio. Probably the only way to do it without installing some extra gear to split the audio path with enough power to drive everything. I doubt that's the cause of the power cycling issue.

Looks like they are powering the CPI box off the back of the CDM via pin 13, which is "switched battery +". I don't recall what the current capacity of that pin is, and it's probably sufficient for powering the CPI box, but I've seen these hooked up with the power fed directly off the power supply. Might be a long shot with zero science to back it up since I haven't done the research, but you could see if powering the CPI box off the power supply directly, instead of the radio, would solve the issue. If the CPI box was pulling to much, it might hose thing up, but I'm not sure what Motorola has in place for pin 13. Would be worth doing some research.

 

[cmdrwill]

Pin 11 should be RX Filtered audio. And that is not affected by the volume control. Line level.