spectra w/ whine, please help

[tommul05]

I have a spectra that runs on a 800Mhz TRS, I removed it from my old POV and put in my new one. Everything works great, but I have a low pitched whine, I guess "altenator noise", it gets worse as the vehicle increases speed, but the altenator is brand new. I re-did the grounds and the power connections. This radio also has a system 9000 siren as well. Any suggestions to help remedy the noise. it is driving me CRAZY. Thanks all! Prior to moving the radio, there was no noise in my old car???

 

[Seadoo]

Change your Spark plug wires. You are probablly picking up the noise from the ignition system through your radios antenna. Use no smaller than 8mm wires.

Seadoo

 

[CCHLLM]

If it's a whining sound that increases/decreases with engine speed, it's the alternator, not ignition noise. If an 800 mHz radio, especially a Spectra, is affected by ignition noise, there are far more problems than just ignition wires. Are the red power wire for the radio, the red power wire for the siren, and the green wire from the control head all connected to the SAME voltage source, i.e., the battery itself or a master switch/relay directly fed from the battery? If not, even with great ground connections (and those should all be at ONE point also), there's the strong possibility that noise and other problems will occur. MotherMoto is rather adamant about attaching the power wires to the SAME source point, and the ground wires to the SAME ground point, and for good reason. Then there's the possibility that I'm trying to tell Noah about the flood here. If so, I apologize.

 

[tommul05]

WX4CBH, Thanks, no need for apology, I am looking for all the help I can get. Both the red wires (radio and siren) are ran to the battery itself. The green wire is ran into the fuse box and inserted into a 20amp fuse socket. This is how it was in the old POV (I think) Any more suggestions? Should I change the green wire and run it all the way to the battery also? Thanks-A- Bunch

 

[jim202]

You just might be getting into the age problem with the radio. there are surface mount electrolytic capacitors used in that radio that go bad with age. The first symptom is audio noise problems like clicking noises.

Another rare problem that I have seen in brand new cars is the battery post is dirty. It makes enough of a connection to start the engine most of the time, but is high resistance to the normal use. Found this on a brand new police cruser a number of years ago. They had all sorts of alternator whine when they transmitted. Put mu voltmeter on the battery post while the engine was running. The voltage was over 15 volts. Pulled the terminals off, cleaned them, then put the battery terminal back on the battery. Never had another problem from that source.

If it was an old car, I would say you might have a bad battery. With a new POV, I would try the digital voltmeter trick and see if you get normal voltage at the battery post with the engine on. You should see about 14 to 14.5 volts. With the engine at an idle, turn on the headlights and put the high beam on. The voltage should stay the same. Then turn on the heater or AC unit. With the headlights and the AC or heater going, you should still see about the same voltage. Last straw is to put the wippers on. This will pull the voltage down a little if your right on the edge of the max output. You may have to shut off the AC or heater if the voltage drops much.

What you have done is to see if the alternator is working correctly. If you have a problem, the alternator will not be able to maintain the voltage and it will drop. This also tells you that you bettr not do much night driving until you fix the alternator. A bad regulator or a bad diode in the alternator will show the same symptoms.

Jim

 

[CCHLLM]

The age/leaking capacitor thing is a valid concern in Spectras made during certain years, is the source of a lot of audio noise problems among other things, and if left unattended, the leakage can destroy portions of the circuit boards. As to the green wire being properly connected, Motorola is adamant about NOT connecting the green wire to the fuse panel. If there's any potential voltage difference between the green wire and the red wire, that difference is where the noise rides, and the greater the difference, the louder the noise. At least up to a point. Beyond a certain amount of differential, the radio will not function properly, if at all.

The audio output is isolated and balanced, and voltage differences create an imbalance, and oscillations riding on the imbalance show up as noise, and ALL automobile accessory fuse panels are covered up with noise. If there's any doubt about that, put a scope on the panel and see what the scope tells ya. You just wouldn't believe what you'll find sometimes. This is why MotherMoto designed the radio such that the green wire should be attached at the same source point as the large red wire.