OT Ford F150 Radio Static

WayneMo · Mar 30, 2013

Today my 95 Ford F150 with only 35,000 miles began static on the radio. It changes according to engine speed both moving and when stopped in neutral and is quiet when the engine is off. I suspect something must be sparking somewhere in the ignition system. I have made no changes recently other than installing a new battery a few weeks ago. It just began today and persists.
Any ideas? The truck is always garaged and is in like new condition otherwise. It has the reliable 300 in. 6 cyl engine with manual transmission.

Jimmy/N.Alabama · Mar 30, 2013

It could be one of a couple of issues. It is a little hard to explain but does it sound a little harsh like a buzz that changes frequency with engine speed or does it sound more like a cleaner tone that changes frequency with engine speed. The harsher sound would be from ignition noise and the "cleaner" tone would be caused most likely from a failing rectifier in the alternator. The easiest way I can think of to determine which one would be to remove the belt for a moment and start it up and see if the noise it there or not with it running. If the noise is gone then it's the alternator and if it's still there it is an ignition issue. Either way you need to figure it out as your radio is telling you something is wrong.

Also since you mention you just changed the battery I would be inclined to suspect the alternator but I would also make sure all the connections around the battery are good especially make sure the grounds are clean and tight where they attach both at the battery as well as the block and body.
Something may have been loosened up when changing the battery.

jb

Texas! · Mar 30, 2013

Back in the 60's (and possibly later) Ford vehicles came from the factory with a device that looks exactly like the condenser inside an old points style distributor attached to one of the voltage regulator terminals and it's purpose was to prevent static in the radio. I don't know if Ford was still using them in the 90's but I'd look at your VR and see if it has one. If it does it probably died.
My 1988 F-SuperDuty with the diesel engine has that static on AM but it goes away on FM. Figure that out!

souNdguy · Mar 30, 2013

i'd be willing to bet a filter capacitor failed or is failing.

here's one thing you can do.. hit radio shack.. go to their parts section.. grab a pack that has a big choke init.. coarse wire.. might even be called a filter choke.. who nows these days.

grab 2 large capacitors.. like 4700 to 6800 uf.. get ones with a voltage range of 16v at least..

wire up a simple pi filter circuit. cap + leg to one side of choke other cap + leg to other side of choke.. that leaves the neg legs.. tie them.

now on yer radio.. find the power lead.. break it.. put the choke inline with hot. and tie the neg legs to radio box metal . if they have any torrid snap ons.. grab a couple and pop them ont he incoming power and the clock power leads.. give em a few wraps of the wire.

some people also will take a lage value cap.. same as above and tie it right between alt charge stud and alt frame.. usually with a ceramic disc cap parralleled with it.

IE.. I think you may be getting alt noise in...

and I'd be monitoring your alt too..

Hobo,NC · Mar 30, 2013

I like removing the belt trick 8) also check are add a ground strap to the hood... If gets a little harder to find if those don't work...

36 Coupe · Mar 31, 2013

Check the ground strap between the cab and chassis.Its on the passenger side.The antenna may have lost its ground connection to the body.AM is bothered the most.If road salt is used it makes a lot of trouble.Eords have a 1/4 inch spade connector on the starter that loses contact.Just pull the connector off and push it back on.Note the green corossion on the blade.This sells a lot of new starters on Fords.

Charles Krammin · Mar 31, 2013

I would suspect that the "noise suppression filter circuit" in your radio has went bad.
All electrical things (including spark plug wires) emite radio signals, at different frenquencies. The filter is mostly adjusted in the AM circuit to short out "spark frenquencies" It is hard to short out all frenquencies (fence row sparker, electrical transmission lines, high wattage transmitters, etc.
This is not a problem in FM as it is "frenquency modulated"
Charles Krammin USMC aviation radio repairman, retired

WayneMo · Mar 31, 2013

Thanks to all you electronic guru"s. This forum is really great in that it has the following of so much expertise and knowledge.
You have given me a lot to work on and I will start and get back with you as I learn more.
Thanks, these O.T. messages are good so long as they do not overwhelm the main topic of Ford tractors. I have 5 of them now and this board has helped me a lot with them!

Anonymous-0 · Mar 31, 2013

Believe it or not.....Sometimes I drive around with my Ford E-150 with the AM dial set to 560am.

I check for leaking transformers around the vicinity of an orchard complex where I do refrigeration service.

We sorta calculate when to suspect a phase loss in our 3 phase services sometime during the summer season. This means emergency service for compressors.

John,PA

WayneMo · Mar 31, 2013

I disabled the alternator and that did not help. Yes, the static is constant and on AM not FM. I could not find a regulator and suspect it is inside the alternator. I did find a capacitor coming off what looks like the ignition coil. That could bear checking out.
The fact that the static occurred all of a sudden upon startup suggests to me it is a sudden failure inside the radio. I did not go into the radio or antenna since that requires more items to remove.

OT Ford F150 Radio Static

WayneMo

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Jimmy/N.Alabama

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Texas!

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souNdguy

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Hobo,NC

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36 Coupe

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Charles Krammin

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WayneMo

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Anonymous-0

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WayneMo

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