Radio shuts off when turning

[Remusa12]

I have a 73 charger with a 440 with the higher 78 amp alternator it had issues charging before so I put a new regulator in the car and it fixed my charging issue. However it still has an issue where the radio will cut out when I apply the turn signals and brake lights at a stop sign. It's an aftermarket pioneer, I also have 2 electric fans and drive with headlights on. I can see the needle dip into discharge when I'm stopped with every thing running and it can be fixed with a little more rpm at idle. My guess is the alternator doesn't produce enough amps at idle which is set at 650 but I need to put it up to 1000 to work.
I don't know my pulley ratio but it's using all factory parts so do I just need a higher amp alternator.

 

[Ron H]

Sounds more like a circuitry issue than the alt. I'd check the fuse block, wiring, and connections...

 

[pnora]

Try it with the engine off and see if the radio quits.

 

[mac]

i found this post somewhere and it explained the exact problem i was experiencing. might be your situation. i also changed voltage reg but ended up changing alternator to solve problem. see if your parts store can test your alternator.

"It is possible that you have an open diode in the 3 phase full wave rectifier circuit. A 3 phase full wave bridge rectifier circuit will have 3 positive and 3 negative diodes. An open diode will present it self as low output voltage at idle but at higher RPMs, appear to be OK but with light loads. If system load is increased, like: headlights, defroster, wipers, the alternator will be unable to supply the additional current. A failure of one diode, albeit a positive or negative diode, will reduce the capacity of the alternator by half of the rated output (current). Alternatively, if the voltage regulator is faulty, it usually presents as low output voltage or high output voltage. If the brushes are worn or the slip rings are dirty, the alternator presents as low output voltage and current."

 

[Cranky]

Also you need to determine what your power draw is with all the things you have running at an idle. You might find that your amp load surpasses what the alternator is putting out at an idle. Sounds like it your alt isn't able to produce high enough amps at idle just like most of them with all that you are running sitting....

 

[Sixpactogo]

I had an aftermarket radio in my 70 Challenger. I noticed my radio would cut out at times and during those times, my Amp gauge would be showing full charge for no good reason. I replaced the voltage regulator and never had the issue again. I believe those newer radios have some protection built in to shut down in case of high voltage or amperage. Yours seems to be the opposite. Maybe they shut down with a lower voltage or amp flow also.
Electrical gremlins.........Gotta love em. Check your grounds. That is what causes most of our issues.

 

[dadsbee]

Just like a Lowrance fish finder.. below 10.9 volts they shut off.

 

[RJRENTON]

i found this post somewhere and it explained the exact problem i was experiencing. might be your situation. i also changed voltage reg but ended up changing alternator to solve problem. see if your parts store can test your alternator.

"It is possible that you have an open diode in the 3 phase full wave rectifier circuit. A 3 phase full wave bridge rectifier circuit will have 3 positive and 3 negative diodes. An open diode will present it self as low output voltage at idle but at higher RPMs, appear to be OK but with light loads. If system load is increased, like: headlights, defroster, wipers, the alternator will be unable to supply the additional current. A failure of one diode, albeit a positive or negative diode, will reduce the capacity of the alternator by half of the rated output (current). Alternatively, if the voltage regulator is faulty, it usually presents as low output voltage or high output voltage. If the brushes are worn or the slip rings are dirty, the alternator presents as low output voltage and current."

I noticed that you quoted my explanation of possible alternator output issues....thank you for the inclusion of the information......but I would have appreciated the credit for my origional comment....out of courtesy.....realizing its not copyrighted.
BOB RENTON

 

[Nacho-RT74]

I'm agreed on the diode failure as one of the posible failures ( and rest mentioned )... or one of the stator windings. A 78 amps alt should feed enough at 800-850 rpms ( BTDT ), to keep most of the car accs working on regular conditions. At least with the small pulley. It is actually my setup, and I can even get the A/C on low speed and lights on ( halogens ) and amm needle mostly centered at iddle.

I have relays for each one of the A/C speeds ( 4 in total ) and headlights ( 2 relays more ) everything sourced from alt side, which in fact will allow better load supply, and still my 78 amps alt is able to respond at iddle, once again, using the small pulley.

Flashers/turning bulbs sucks a lot of load and Radio is on same line. Its in fact spliced from the flasher plug itself. With stock radios sometimes you could get a volume decay when turning on turnings if load is not enough for it. So a modern radio could be turned off being feeded from the same line if is this decay is really noticeable.

 

[mac]

I noticed that you quoted my explanation of possible alternator output issues....thank you for the inclusion of the information......but I would have appreciated the credit for my origional comment....out of courtesy.....realizing its not copyrighted.
BOB RENTON

not my intention to take any credit for the info i posted. just found it very useful at the time i was experiencing the problem i was having with my car.

 

[Sinitro]

The current draw of (2) electric fans and headlights exceeds the capability of your alternator. Note that (2) fans typically can draw up to 60 amps, U need to upgrade the alternator and supporting wiring to handle the higher current.

Just my $0.02...

 

[WileE]

Classic radios automatically shut off when tuned to a station playing Rap Crap.

 

[RJRENTON]

Classic radios automatically shut off when tuned to a station playing Rap Crap.

ABSOLUTELY CORRECT.....another form of "air pollution".....
BOB RENTON

 

[Nacho-RT74]

I haven't read it about the fans setup. If so, then even with the 78 amps alt you are still short of power. Even more if they are linked to work together. Maybe if you have them set for diff temp rate each could be diff. But definitelly Need a more powerfull unit.

I wouldn't say they could draw 60 amps. Maybe at start up, but I think average each one could be on 15-20 amps rate. If you don't have the specs of them, the wire gauge of the units could give you a clue.