From Newsgroup: sci.electronics.repair

On Thu, 17 Jul 2025 11:22:26 -0400, Michael Trew
<michael.trew@att.net> wrote:

On 7/16/2025 1:28 PM, Adrian Caspersz wrote:
I think I shorted something inside of the radio. I bought a truck with
a chopped radio wiring harness. I repaired the truck's radio harness >wiring, but I somehow shorted the hot wire off of the radio ground when
I was installing the radio.

My guess(tm) is that you somehow reversed the power polarity. Use a
DVM to check the polarity with the radio unplugged from the truck's
12V wires. Tracing the wires is nice, but a measurement is better.

Also, some details would be nice, such as the year of the Ford Ranger
truck and if possible the model number of the AM radio. Extra credit
for posting a photo of the repaired radio harness.
--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558
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From Newsgroup: sci.electronics.repair

In sci.electronics.repair, on Thu, 17 Jul 2025 22:43:31 GMT, "John
Keiser" <johnkeiser@juno.com> wrote:

Michael Trew wrote:

Hello,

I bought an old Ford Ranger digital AM clock radio from a
pull-a-part. I was surprised to learn that they bothered to make an
AM-only digital radio by the 90's. One would think after analog
radios, it would have been cheaper to make all the "new" digital
radios AM and FM. I figure it's rare to see one of these AM radios
today, not replaced.

Someone chopped the radio wiring harness in my truck (I wish I saved
the harness from the yard). I wired another harness in, but I
somehow shorted the hot wire off of the radio ground, I believe. It
make a quick spark at first, and now the radio doesn't function. The
back-light will illuminate when the headlights are turned on, but
that's it.

I'm hoping someone has an idea on how to fix this. I'd like to wire
in a closed circuit 1/8" AUX audio jack, and use the radio in my
truck. I did that with a stock GM Delco radio once. As soon as you
plug the jack in, it cuts the radio off. I don't see anything burnt
inside the radio. Maybe I need to replace a capacitor or resistor?

Thank you all in advance for any solutions!

Isn't it more likely that you blew the car's fuse feeding the radio.

Yes, definitely, based on "I somehow shorted the hot wire off of the
radio ground, I believe". How would this involve the radio itself?

I think the backlight circuit is separate from power.

Yes, the same circuit that powers the other dashboard light, so you can
make them dim or bright.
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