CDM1250

[firefighter13669]

A few questions regarding the CDM1250 and problems

A agencie had a CDM1250 places into service and had it made into a dual head radio with an after market kit.The radio had several issues while in service so it was pulled.Later down the road it was set up as the base radio and these are the problems I have found if someone could help me

The display in the head of the radio cuts in and out and sometimes shows no display.This happens no matter what head is hooked up .BTW using it as a single head radio now.

They have the radio hooked up to an old GM300 fitted power supply.The fan is broken in the power supply and at one point the radio got so hot you could fry an egg on it.

When you touch the back of the cdm1250 radio uit you will get an electrical shock most times

.....The Local Motorola Two way radio shop said their was nothing wrong with the unit and the display is cutting in and out because of loose parts in the heads.Now to me that doesnt make any sense because it happens on both head.You should not be getting current on the back of the radio and I was wondering if maybe when the radio got heated up for a long time that may have caused an internal problem.....Any Ideas on these issues would be great

[486dx4]

More questions than answers but here it goes....

Can you better define what you mean by cutting out on the display? When you do not see anything on the display does the radio still receive and transmit? Can you try the two control heads on another 1250 to see what happens - to see if the problem "moves"? From doing the last part you can see if the issue is in the head or the radio itself. If you have another white flex cable that goes between the head and the radio to try out you can see if that may be the culprit.

As for the shock, the motorola shop I gather said they did not find the issue using their power supply for bench testing so the shock may be coming from the supply you are using (bad grounding - who knows). If you can swap in another DC supply of the same rating or better and the shock goes away that would give you a clue.

[firefighter13669]

The problem with the display is that it will sometimes stays on so you can rx and the display screen light is on .sometimes the alpha numeric display is all messed up so you dont know what the channels are and sometimes the radios just goes lank no display no lights ects but will clicker back on with in 5-8 secs

[jackhackett]

You have to be careful when swapping heads on the CDMs, the circuit board is just held in by the pressure of the housing, and when you put the head on the radio the housing gets flexed, if you don't do it just right the board will often pop out as the head is pressed onto the radio.
If you're getting a shock from the radio chassis only when transmitting, it is probably RF on the chassis caused by a problem in the antenna system. If you get a shock even when not transmitting it would be a problem with either the power supply, or the electrical outlet.

[firefighter13669]

Yes the shock from the radio is there all the time.The heads have been switched to see if they both have the same problem becasue they say it was just the one head however both have the same problem the will just blank out when ever they want sometime you need to turn the ower off on the power supply and power it back up to get the display back just using the power button on the radio does not alwas work

[Batwings21]

I have installed two of those dual head cdm setups, they both were terrible. I had the exact same display problems. Are you still using any parts of the dual head kit or did you reassemble it to the radio? Because the dual head kit did not hold the display together right, causing those symptoms.

[firefighter13669]

NO we are not using any of the after market head setup

[jackhackett]

When you say the display goes blank, do you mean the display is blank but the radio is working otherwise, or is the radio actually shutting off?

[firefighter13669]

It all depends sometimes it dies and turns back on sometimes you will have sound and no display but will have the lights

[thebigphish]

I would say "Good thing it's only a CDM." It's a cheap unit to replace, and it may be in your best interest to purchase another radio, and use that one for parts (buttons and such, things you KNOW work)

[Garyf629]

I will almost guarantee you the problem is loose boards in the control heads. Anytime you separate the control head from radio, you risk the chance of the PCB's becoming loose. The boards in the heads on these radios are held together by plastic tabs on the housings. If the boards are loose try pressing down on them till you hear a snap. If you don't hear that snap, or the boards are still loose, the snaps might have been broken off, or are damaged. You may need to replace the housing, but considering the problem you are having, I would suggest you replace the whole control head. They are not that expensive, I do not have my service manual at home, so I can not give you the part number, but heads for the 1550's are around $175.

On the dual head kits, this has been covered many time here. I have over 30 of these units in service. Some over 5 years old, and used all day, every day, with no failures. If they are installed correctly, by qualified people, taking no short cuts, they work fine. They are certainly a lot cheaper than a Motorola dual head capable radio. I removed 6 dual head MCS-2000's, replaced with dual head CDM-1550's and have had no problems. The MCS's were nothing but headaches, even our local Moto dealer didn't want anything to do with them any longer, and they sold them to us!

[jackhackett]

I would start with the electrical shock problem, check the AC outlet, you can get a thing that plugs in and tells you if it's wired properly for under $10 (home depot has one, sku 398469), and try a known good power supply.

Fixing that problem might clear up the radio problem as well, and if you were to go with a new radio you wouldn't want to put it on a possibly bad supply and risk damaging it.
If the supply has a fan in it like you say, it's probably a switcher... when those go bad they can do all sorts of weird stuff, like put out too much voltage, or have lots of high frequency noise in the output which can drive the radio's processors crazy.

If the display still cuts out on a good supply, try taking the head off, reseat the circuit board, and run it with the head off the radio, just connected by the flex cable (to avoid dislodging it again), if it still cuts out there's probably a part going bad in the radio.

[nmfire10]

Lets back up a second here. I agree with Jack. Fixing the elctrocution problem should probably be the first course of action. When you say you are "getting shocked", what kind of shock is it. Are we talking about a static shock or is there 120v running through your arm? This could very easily piss that radio off. As you probably noticed, the CDM is very easy to piss off and having high voltage rammed up its ass is not going to help anything including the display.