Electrical power for radio

GS850_Mike

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Ok I know we don't all ride the same bike or even the same brand but I am wondering if anyone else has seen this.
First the bike is a 1982 Suzuki GS850G. It has a new (made by me) wiring harness, i replaced every wire and the main wirinig side connectors. This means any device switch or what not kept its half but the wiriing side was replaced. Example harnes and connector is new but connector to turnsignal is original. The bike has a "heavy duty" stator and a new sh775 voltage regulator (non-shunt type). I have not had any charging issues even running full heated gear. I havebused my battery to charge my phone and other toys while camping and the bike fires right up and ready to go every morning.
I have installed a Vetter fairing and recently installed a cyclesound radio. This brings my long winded post to my question originally I had the ignition wire for the radio connected to the factory spare wire with the lights. When testing and most of the way through my trip it worked flawlessly. However on my way home (about 1200 miles into my trip] the radio started to have a problem... everytime I used my turnsignals the radio would reset. You might not thinl this is that bad but I always use my turnsignals. Actually it's amazing I haven't ran out of turnsignal fluid yet. When I got home and started testing it still resets everytime i hit the turnsignal. I have correcred the annoyance by running a new wire to my accesory relay that I added but would like to know why this has started so I can repair and correct this before something else starts acting up. Also for everyones knowledge the same wire I did have the radio connected to is the signal wire for my accessory relay.

Any thoughts would be great.

And I am sorry it's a long post but I wanted to answer as many things I could before they were asked.
 

Scott-E

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Current is common in each circuit branch in DC electrical systems. I'm assuming you are still using filament bulbs in your turn signal and headlight circuits. By connecting your radio to the lighting circuit branch you have connected your radio to a relatively high current circuit. What's happening to your radio as a result is the circuit voltage is dropping below the point in that circuit where the radio will function correctly when the turn signal bulbs illuminate. The solution would be to isolate the radio from that circuit by using a relay. The lighting circuit can still be used to activate the relay so the radio is powered up when the lights are "Hot" while the switch part of the relay is connected to the battery so it's own it's on branch circuit. Here is a diagram showing how to hook it up.

Terminal 85 connects to the lighting circuit.
Terminal 87 connects to your radio (Device).
Terminal 86 connects to ground.
Terminal 30 connects to the battery.
 

GS850_Mike

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I assumed that is what is happening and yes that is the way I solved it. But the real question is why was it fine for over 1000 miles and then started happening? Also even at idle I have positive voltage 12.9 or better at highway speed I can't believe my system with the current upgrades couldn't support the extra load. Also the only thing on at that time was the radio (yes the headlight, on its own fuse and is led, and turnsignal also on a separate fuse were on) and once it restarted the radio would stay on until you would restart the blinker.... so it was not the turnsignal itself it has to be the initial blink so maybe the blinker relay? Guess if I really want to k kw I might have to resort to breaking out the oscilloscope and try it....blah.
 

Scott-E

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I assumed that is what is happening and yes that is the way I solved it. But the real question is why was it fine for over 1000 miles and then started happening? Also even at idle I have positive voltage 12.9 or better at highway speed I can't believe my system with the current upgrades couldn't support the extra load. Also the only thing on at that time was the radio (yes the headlight, on its own fuse and is led, and turnsignal also on a separate fuse were on) and once it restarted the radio would stay on until you would restart the blinker.... so it was not the turnsignal itself it has to be the initial blink so maybe the blinker relay? Guess if I really want to k kw I might have to resort to breaking out the oscilloscope and try it....blah.
It could have been caused by AC voltage spikes generated by the flasher can. If it's a thermal type flasher relay (as most are) when the relay contacts open a high voltage spike is generated on the DC Power Line. That spike could have damaged a capacitor in the DC Power input filter in the radio. All automotive radios have those small filter circuits that remove ignition and alternator noise from the DC Power input so the radio audio output in the speakers is clean. They also are required to keep those voltage spikes from interfering with modern digital control circuits found in all modern radios. Isolating the radio from that lighting circuit eliminated that interference. Connecting the radio to the battery also eliminates those problems as lead acid batteries do a really good job of filtering out DC Line Hash and Noise. Placing a diode across the terminals of the flasher can will short out and eliminate the AC Spikes they generate. Modern electronic flasher relays have none of the problems of thermal type flasher type relays. Below is a picture of a thermal relay with it's cover removed.

This is the circuit diagram of a typical DC Line Filter.
 
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Larry Fine

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Another possibility: an increase in the resistance of a ground connection, especially a shared connection.
 

Dave Ireland

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It's a GS - the recycled copper in the factory connectors is trying to rejoin Mother Earth, 24 hours a day. You got 1200 miles of trouble-free running just to lull you into a false sense of security.
I'd tend to go with the common connector idea, for the first examination, either feed or earth. After refurbishment it was fine for a while, but well, it's a GS.
Years ago I got into the routine of yearly disconnect, clean and re-make / re-new every dodgy one. I did this every autumn, as there's nothing worse than spending a cold winter afternoon in the middle of nowhere trying to trace an electrical fault.
Bullet connectors belong on a 1950s car. If I were sensible I'd rip the lot out and re-wire from scratch with all new wiring and weatherproof connectors to modern standards.
 

Scott-E

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If I were sensible I'd rip the lot out and re-wire from scratch with all new wiring and weatherproof connectors to modern standards.
I did that to a 1967 VW Beetle once. That car had really bad electrical problems. The lady had brought it in because no one else would touch it. After looking it over I discovered why. The wiring harness that runs from under the hood to the engine compartment had shorted and melted inside the body. She had made a down payment for the repair so I went ahead and started working on it. I had to attach a Come-a-Long to the wiring harness and a tie down on the wall in order to pull it out. I also attached a rope to the harness that would be used to pull the new harness through the body. I was about half way through pulling out the old harness when she came in to check on the repairs. She saw what I was doing and thought I was destroying her car. I showed her the melted insulation and assured her the car would be as good if not better than new with it's completely new wiring harness and yes, I could pull new wires through the body. I also told her it was a miracle the car had not caught fire and burned when the original harness shorted out and melted the insulation around the wires. She left not quite convinced I could do it. The next day I finished up the wiring job including running new speaker wire and extra wires for future accessories such as an audio amplifier and a heat boost fan to greatly improve the car's heating system. She was relieved her car was properly fixed and happy to pay her bill.
 

GS850_Mike

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Well gentlemen I am happy to say that I have found the problem and a little embarrassed too. Earlier this week I rode the bike an easy 100 miles. The radio started acting up close to home so I shut it down and just used my helmet audio. When I got to my destination I shut down for a few minutes only to find the bike wouldn't start. I got a jump from a nice motorist and made my way home. Once home I knew it had to be something simple because I have replaced almost every wire and connector. Turns out the positive terminal on the battery had become loose. It was arching and ate a good portion of the battery contact. But once I re-secured the battery terminal, everything is fine. All is fixed (going to have to replace the battery sooner than later) and the radi9 no longer cuts out with the turnsignals.
 

GS850_Mike

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Haha. Kind of embarrassing really as I work as an Aircraft Mechanic. I never had a battery terminal come loose before now. Also no other obvious clues as to the battery, bike started fine ran fine headlight turnsignals all worked.
 

Larry Fine

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Don't feel bad. An H-D owner I know didn't realize the battery's negative conductor needed to be at least as large as the positive conductor for starting current. The resulting heat from the #12 wire melted the battery's negative terminal.

I usually replace battery bolts with longer ones when adding accessory terminals, so there is room for multiple lugs and a lock-washer.