Dead Becker GP needs Help!! - PeachParts Mercedes-Benz Forum

Phalcon51 · #1 08-25-2004, 08:34 PM

I originally posted this problem in the Tech Forum, and although the replies I got were helpful, they didn't really address the problem. I'm hoping you folks in this forum might be a little bit more radio-wise. The original post is here

Long story short; The Becker GP (model 754) in my '86 300E died and I'm trying to figure out whether the problem is in the radio or the wiring under the center console.

My initial question at this point is this: I'm getting 12 vdc only on the red/white wire in the 4-pin plug to the back of the radio. this is with the ignition key on or off. No voltage is present at any other connector. The ground is good. I was talking to a repair guy on the phone who had a heavy accent, and he said it needs 3 voltages to run. I'm not sure if he meant that it needs 12v at 3 different wires or that it needs 3 different voltages at different wires. He didn't have time to elaborate, so I'm still confused. Can someone tell me what voltages have to be present on which wires for this radio to operate?

All right, that's actually more of a statement than a question, but at least it ends with a question. Right now it's completely dead. No display, no lights, no noise at all. I'd appreciate any help you can offer up.

Gary

Phalcon51 · #2 08-27-2004, 06:33 PM

Hellooo...........is anyone home? Boy, it sure is quiet in this post. Can anyone give some advice on this one?

Scott from La Jolla Audio, are you out there??

Thanks

speedy300Dturbo · #3 08-27-2004, 06:45 PM

In order for the radio to turn on, you need 12V at the red and black wires. Red wire should read 12V at all times. The black wire should read 12V only when the car is switched on, and the brown wire should be grounded. The grey wire is for illumination.

dakota · #4 09-04-2004, 01:46 AM

Are you sure that it isn't the lithium battery that is dead inside? The model 754 radios found in vehicles from 1986-1987 were not designed to deactivate when the battery was disconnected. If the 754 is doing that, it simply means that the radios internal lithium battery is dead and it needs to be replaced. Once replaced, you can disconnect the vehicle battery until your "blue-in-the-face" and it will not dash-out on you.

Anyway, not sure what voltages you should be getting.

Phalcon51 · #5 09-04-2004, 04:31 AM

Thanks to all for thr replys.

Dakota,

I hadn't disconnected the battery at all. It's simply that the radio was working when I parked the car at work and shut it off, and then it wasn't working when I got off of work and turned it on. The display isn't "dashed out", it just isn't doing anything. It's completely blank. Whatever power needs to be present to make the radio turn on is just not there. As I said before I've got 12vdc at the red/wht wire going into the back of the radio with the key on or off, but no joy and no power at any other wires. If it is the lithium battery, I'm sure it's long since died seeing as it's going on 19 years since the battery was new. Does it use any kind of standard lithium battery that I can purchase from a camera or electronice store? Anyone got a number?

According to speedy300Dturbo I need voltage at the red and the black wire, and ground at the brown wire. I'm hoping to get the time to check these this weekend, but for the last week or so I've been trying to repair a leaky gas main at my house. Major problem compared to the radio, especially since the gas co. shut off the gas saying the problem is in my part of the line. The contractors want $7500 to lay a new pipe so I'm trying to repair it to buy some time, at least.

Gary