CDM 1250 No powwer

[JD]

I have a 10 year old CDM 1250 VHF radio, 45 watt. It will not turn on. It is programmed for ignition sense, I have checked all the volatages in the Supplu Voltage Section , and voltage regulators, all check.
Only one that seems suspecious is on the voltage supply section. It is labeled "Battery_Voltage". It measure 3.3 volts, appears this is a voltage divider circiut. i calculate around 10.4 volts.
Thanks.

[jackhackett]

Calculate that again.... according to the schematic I'm looking at it's a 30K and a 10K resistor for a total of 40K, measured across the 10K, so you should see 1/4th the voltage, 3.3V * 4 = 13.2V, looks about right to me. There's also supposed to be a 5.6V zener across it, so it shouldn't be higher than that anyway.

edit: looked again, zener marked as NU, so it's not actually there... not that it matters to the results here.

[JD]

Your right, any ideas what else it could be ?

[jackhackett]

I've heard that the 16.8MHz oscillator can go bad and that will cause the radio to not power up as the micro derives it's clock from it.

There's also the fuse for FLT_A+ to the control head... I think if that's blown you'll still get a power up beep though, but it's something easy to check for.

[JD]

There is power on the control head , radio is 10 years old, do not want to put too much into it. Thanks.