Positive Ground Systems

phoyer · Post by **phoyer** » Wed Jul 28, 2004 8:01 am

I'm working on a Fire Truck, a rather old one, that has a positive ground system. We are trying to install lights sirens and radio. We have an old Q-siren from Federal Signal a CDM-750 radio and a huge LED light package to install. I can't seem to find a converter that can handle even the amperage involved in the light system alone. Can anybody help me out here?

KB2ZTX · Post by **KB2ZTX** » Wed Jul 28, 2004 9:41 am

Well ... you might have a battle with this one. Most lights and stuff will work either way, but the radio might be tricky. We use junk astron convertors for radios, but then have to also isolatethe antenna. We've never had good luck with this.

On a couple of vehicles we actually switched the whole truckt to neg ground...a mess...

jas

phoyer · Post by **phoyer** » Wed Jul 28, 2004 10:23 am

Yea I'm trying to see what it's going to take to switch the truck. I'm not sure it's a viable option yet.

spareparts · Post by **spareparts** » Wed Jul 28, 2004 1:03 pm

phoyer wrote:I'm working on a Fire Truck, a rather old one, that has a positive ground system. We are trying to install lights sirens and radio. We have an old Q-siren from Federal Signal a CDM-750 radio and a huge LED light package to install. I can't seem to find a converter that can handle even the amperage involved in the light system alone. Can anybody help me out here?

Newmar makes several isolated convertors. An isolated convertor eliminates the radio antenna ground issue. However, the biggest I've seen is 40 amps output @ 13.8 VDC. That would easily take care of the CDM and any reasonable LED package you could install.

However, There's little chance you will find a convertor for the Q. Best bet is bite the bullet, and rewire the truck for 12 volt negative ground.

What make is the truck? The worst thing in a conversion is usually the starter, followed by the ignition system.

Martin

MassFD · Post by **MassFD** » Wed Jul 28, 2004 6:05 pm

Did you try the Q on Pos ground, I do not think it cares as it has wound field coils. The only differance should be how the solinoid and switch are wired.

If it was a later permenent magnet field motor it would run backward but no damage would be done, give it a try.

Tech225 · Post by **Tech225** » Wed Jul 28, 2004 7:03 pm

MassFD wrote:Did you try the Q on Pos ground, I do not think it cares as it has wound field coils. The only differance should be how the solinoid and switch are wired.

If it was a later permenent magnet field motor it would run backward but no damage would be done, give it a try.

If you were to run a Q backwards, wouldn't it just suck in everything in the universe like a black hole?

joe1234 · Post by **joe1234** » Thu Jul 29, 2004 11:04 am

Sell the truck and run while you can........................................

phoyer · Post by **phoyer** » Thu Jul 29, 2004 12:25 pm

Thanks for the info folks. It is an FWD fire truck. We think we have found someone to convert the truck so that's probably what we'll do.

Mike in CT · Post by **Mike in CT** » Fri Jul 30, 2004 6:01 pm

Yep, In the great cosmic scheme of things, if you run a Federal Q backwards, it takes in ALL the sound of the universe, and sends it down the wires into nothingness.

So you wont hear a thing coming out of it, and slowly, but surely, all the sounds around you will go away. neat!

faaaaaaar out sireeeeeen, the Q...

time for my meds...

Mike in CT
KM1R

Positive Ground Systems

Positive Ground Systems

Positive Ground

Re: Positive Ground Systems

Thanks

Fed Q