Radio anomaly

[lada03]

Hello,
You guys probably see me around the forum as the radio guy that for the past 15 years have reunited many original radios with their rightful cars.

I like to take pride in what i do, but for once Im stumped on a radio installation.

So i have an 85’ 911 carrera. I had a blaupunkt charleston installed, removed the Charleston in favor of the Blaupunkt Reno.

Well, the Charleston worked great. However, When i connect the Reno, the radio in the car does not power on. I took a multimeter, the positive wire is not delivering 12v to the radio when connected. When the radio is not connected, I have 12-13v power to the wire.

I dont get it. I bench tested the reno, works well. But when I connect it in the car its not getting power. Somewhere along the way there is a bad connection or possible short?

I cant track it down. I have another radio laying around, it powrers on fine in the car

Loosing my mind.


Oh and i tried both power wires one from battery and one from ignition.. nothing

[ErrorMargin]

First, I find that a single shot of bourbon to be helpful in these situations...

Next, does the radio power up and work fine on the bench? I think you said yes, but just double checking.

How are you determining that there is no power to the radio when connected?

I'd try connecting only the power wires...disconnect all the speaker, antenna and other wires from the radio harness and just focus on getting the radio to power up.

[RSTarga]

A grounding problem?

[lada03]

Lol, oh I had a beer (or 2) to calm the nerves

Radio works perfectly on the bench. I literally connect an old blaupunkt richmond with the car wires and it powers on. I unplug the radio, plug in the reno. No power coming in

I determine there is no power going to the radio with a multimeter. Not getting voltage to the radio positive terminal

Yes, only concentrating on power wires. Both ignition and battery positive wire. Speakers/antenna unplugged

Originally Posted by ErrorMargin

First, I find that a single shot of bourbon to be helpful in these situations...

Next, does the radio power up and work fine on the bench? I think you said yes, but just double checking.

How are you determining that there is no power to the radio when connected?

I'd try connecting only the power wires...disconnect all the speaker, antenna and other wires from the radio harness and just focus on getting the radio to power up.

[lada03]

Ground ok. Its like there is a power drain.. fuses looked good.. im
Stumped.. dont wnat to start digging to deep, tracing the wire back tonthe battery

Originally Posted by RSTarga

A grounding problem?

[lada03]

So you guys dont think im crazy.

The 1st radio (richmond) powers on with 2 wires.

The 2nd radio (reno). Does not. Same 2 wires connecting the radio



M


VS

[Tea Tray]

Probe a test light into the suspect radio feed wire. Make sure you have a known good ground connection.
With no radio connected and power on, is the test light normal brightness?
Connect radio and repeat test.
If the bulb dims then there is a bad connection somewhere between the test light and power supply point.

[lada03]

Dont have a test light probe.. will have to get one

[blucille]

Analog radio only needs switched power. Digital radio needs constant power for memory in addition to switched power. Won’t power on without both power feeds.

[lada03]

Reno, doesnt need constant power

Just ground, switched power positive and display illumination

[blucille]

The manual makes it pretty clear that constant power is required. As is switched power. I find it hard to believe any digital radio doesn’t need both constant and switched power.

[lada03]

I hooked it up the same as this guy in the video

https://youtu.be/76qxTJKV9WQ

[lada03]

Problem solved.
Weak ground wire. It was strong enough to power on one radio but not the other

Got a fresh ground, works great