CDM1250 power help

[ICEMANTIM]

Need help with a cdm 1250. I have it wired to a spot in my fuse box that is not turned off with the keys. When i turn the car off the radio turns off and i have to turn it back on again. I do not understand why this is? It is not hooked up to the key but turns off when i key the key off. I checked the fuse box and it has power all the time. I found a place in the software that talk about ingintion senceing. I turned that off and still had the problem. Any ideas. Thanks

[thebigphish]

are you positive that the exact terminal in your fusebox is hot all the time?

[ICEMANTIM]

I checked the terminal and it has power when the key is on and when the key is off. The radio works fine when the car is not running. The radio turns off when i turn the key off, but i can turn the radio back on and there is power. ?? Thanks

[thebigphish]

ok, well. backpin the connection to the CDM when you turn the key off, with a voltage meter and see what happens. You may be getting a voltage drop, that is just enough to kill the CDM. (oh, and do you have a IGN sens line set up? to the right pin?)

[jackhackett]

Rather than trying to figure out why an improper installation doesn't work, why not try installing it properly?

You should not be connecting the main power for a CDM to the fuse panel, the red lead should go to the battery positive terminal, and the black lead should go to the chassis ground (where the wire from the battery negative terminal is bolted to the chassis, NOT to the battery terminal). Then if you want ignition control you can connect the ignition sense lead to a suitable point in the fuse panel.

[ICEMANTIM]

I was thinking that was problem. I did not want to go threw the fire wall. I thought that the fuse box was getting a voltage drop with was causeing the power to drop to the radio for a short time. Thanks for the help. Tim

[57Shasta]

Not getting into the fray of proper installation practices, you are probally losing just enough voltage that causes the radio to shut down or whatever.

Now for CDM TRIVIA! I had a customer who complained that the radios did not power up when the vehicle powered up (via a charge guard) OK I said, not a problem. I added a ignition sense lead to pin 10 of the accessory plug and changed the parameters in RSS. Well no matter how I wired it up or what the RSS parameters were set at, it wouldn't fire up when power was applied to it.

Arrggg!

The aggravating thing was some vehicles did power up by themselves! OK whats the difference? The ones that did had an external speaker plugged into them. Well it's not the speaker doing it, it's the little jumper between pins 7 and 9 (supposed to keep the emergency line grounded).

So if you have a CDM, find a maxtrac and poach the shorting plug from the acc connector and plug it into the CDM. If you now remove power from the CDM with it turned on, it will come back on when power is re-applied, with no ignition sense lead and RSS disabled even!

Screwy /\/\

[ICEMANTIM]

Thanks 57shasta
I had a 16 pin plug from an old gm300 and it worked greast. Thanks Tim

[jim]

"Well it's not the speaker doing it, it's the little jumper between pins 7 and 9 (supposed to keep the emergency line grounded).

So if you have a CDM, find a maxtrac and poach the shorting plug from the acc connector and plug it into the CDM. If you now remove power from the CDM with it turned on, it will come back on when power is re-applied, with no ignition sense lead and RSS disabled even! "


Huh?

Pin 7&9 have nothing whatsoever to do with a CDM powering up automatically.

[Nand]

Huh?

Pin 7&9 have nothing whatsoever to do with a CDM powering up automatically.

But they do, as 57Shasta showed!

Jumpering accessory pins 7 and 9 on a CDM radio will indeed let the radio come on by itself after the main power is removed and reapplied. Both the circuit description and the diagram will make this clear. The emergency pin (9) not only signals to the radio that the emergency button is pressed, but in CDM radios it also wakes up the radio is case it was turned off.

The proper way would be to connect the ignition control line to the main power source or install the not placed 47K resistor (R0542) for this purpose in the designated spot near the accessory connector.

Nand.

[jim]

Yes- this will power it up due to the emergency function's duties, but it is not designed for this. Pin 10 is. What happens if you actually use the emergency feature?

7&9 do actually have nothing to do with radio turn on. The turning on from 7&9 is a side effect of the emergency function. Use pin 10 and do it right!

[Nand]

You are (purposely?) twisting the point here. 57Shasta wrote that the radio will turn itself on when power is applied and pin 9 is jumpered to pin 7 without the use of ignition control. That is about all he said and exactly what it does. He clearly was not using emergency signaling.

CDM radios can do this because Emergency pin-9 among others directly control the turn on of the main 9-volt regulator and the internal switched B+ lines in the CDM radio.

Check the “Controller Schematic Diagram - Supply Voltage” diagram in the service manual. The following is a cut and past from that manual.
This is hardly a side effect since the radio needs to be on before it can do anything else.


The electronic on/off circuitry can be enabled by the μP (through ASFIC CMP port GCB2, line DC
POWER ON), the emergency switch (line EMERGENCY CONTROL), the mechanical On/Off/
Volume knob on the control head (line ON OFF CONTROL), or the ignition sense circuitry (line
IGNITION CONTROL). If any of the 4 paths cause a low at the collector of the npn transistor within
Q0661, the electronic “ON” is engaged.

Nand.

[jim]

I fully understand WHY it turns on like this, but that is not its intended purpose of those pins. Motorola assigned pin 10 for turn on. 7&9 may be jumped on a Maxtrac, but a CDM isn't a Maxtrac.

I can add a relay to the power switch's contacts to turn it on too. It will work, but there's the right way to do it.

[Nand]

Huh?

Pin 7&9 have nothing whatsoever to do with a CDM powering up automatically.

Great, since you do understand how the CDM powers up, you agree that your previous statement above is incorrect?

I am not arguing that this is the proper way to do this, but jumpering pin 7 and 9 does turn on a CDM radio as 57Shasta, ICEMANTIM and Motorola confirmed. You may also note that I already outlined the proper method in my original reply.

Nand.

[tkiuntke]

Whats funny is you are both right. Yes, the emergency pin does what you describe NAND and yes Jim it's not the proper way to have an ignition sense install. The reason why though is that if you DO hook up pins 7 and 9 you get a constant current drain of around 250 mA that will drain a battery if given half a chance. I found this out the hard way when I did a couple installs for a local power district but couldn't figure out why the batteries were all going dead. A little quick work with a DVM and the rest was history.

[Nand]

There was never an argument about what is the proper way or is not. I strictly objected to Jim’s statement that jumpering pins 7 and 9 has nothing to do with powering up the CDM radio.

As it is, when these pins are jumpered, the radio will turn on by it self when main power is connected without the use of an ignition control line.
This likely also explains your 250mA power drain since the radio is turned on.

Nand.

[tkiuntke]

My apologies for not being clear. I should have said that the 250 mA drain was present when the radio was thought to be off, i.e. no lights or display, etc.

[jim]

And I still stick with what I say: 7&9 have nothing to do with powering up the radio. 7&9 were never intended to turn on a radio. They DO have something to do with EMERGENCY...which has the side effect of turning on the radio for emergency transmit. 7&9's characteristics were designed for emergency signalling. "M" didn't put them there to turn on a radio- that's whay they gave us pin 10.

I can install a 16-pin accessory connector onto a microphone and make it work, but they already come with a modular mic plug to go into the front of the radio, which is the correct way to plug the mic into the radio!

[wavetar]

I think we're missing the point that he wasn't using ignition sense at all, he had it wired to constant power & it was still shutting off when the ignition was turned off. Since he's happy with the resolution of his problem, I don't see any point in keeping this going.

Todd