sammicurr86

Changed battery to an AC Delco in a 70 Cutlass (350 Gold Rocket engine) and now the Stereo system won't turn on. The stereo is a JVC KD-S790 and all the fuses have been replaced with new ones. So whats going on and how do I fix it?

Thanks!

oldcutlass

Changing a battery should not effect your stereo other than losing all your saved settings. Check your power wires to the stereo.

Lady72nRob71

Were there any wires connected right to the battery that were not reconnected?
If you accidently connected the + and - backwards, even for a split second, the logic circuitry in the radio could have been destroyed.

Those are all I could think of...

MDchanic

Pretty sure all the modern radios have input diodes to prevent that sort of thing, but you never know.

I'd vote for the un-noticed moved wire as well.

Either that or the radio has some sort of an initial-start mode that requires holding the on-off button down for a long time, or something similar.

- Eric

Lady72nRob71

True, but they are pretty small, like 1 or 2 amp. How much current is the fuse rated for? If 10A, the diodes would pop and open and the destruction begins. I learned this the easy way when I repaired rdios at Circus City 20 years ago...

This thing did not require a code did it?

MDchanic

Fair enough. In which case, all he'd have to do is replace the diode, which had acted as a fuse. Easy!

That is, if that's his problem...

Still betting on a loose or misplaced wire .

- Eric

Lady72nRob71

The diodes were in parallel to the rest of the circuitry, not in series like a fuse would be. The idea would be to try to blow the fuse, but Murphy's Law said "no".
Once the diodes opened, the logic ciruitry often toasted.
However, i am hoping that polarity was never reversed int he OP's case.

MDchanic

Ah. You're talking about a diode placed so as to allow an essentially unresisted flow when connected with polarity reversed, in the apparent hope that the current thus flowing through the diode, and bypassing the rest of the circuit, would be enough to blow the fuse and save the radio. If diode goes before fuse, then circuit is subjected to full voltage (and potentially full current up to the value of the fuse), which, as Egon Spengler said in Ghostbusters "... would be bad."

- Eric

oldcutlass

All things electrical and a lot of things mechanical, are manufactured with specific amounts of smoke stored inside of them. When they break and the smoke comes out, they no longer function!

rocketraider

Did you install this radio yourself or did the stereo dealer install it?

Right now I'm thinking the unit is code-protected for theft deterrence and you will have to re-enter that code before it will work. The code and programming procedure should be in the stereo's owner's manual. Most code-protected units are set to go dead if power is interrupted to them.

If you don't have the code, you will have to jump thru hoops to get it. It would be simpler to to trash the thing and get a new one.