My antenna motor is a transformer!! - PeachParts Mercedes-Benz Forum

zu! · #1 03-31-2018, 03:07 PM

At least it sure sounds like one! I was working on something else in the hatch and noticed a clicking and whirring sound...like something was trying to do something, but not quite succeeding.
Put my ear to the antenna motor and it was coming from there!

Unplugged it and the sound stops. Otherwise, it works flawlessly, going up when the radio is on, and even follows the switch on the dash (for medium, high and off).

What gives? Is there some sort of switch inside to switch if off? I don’t want to leave it plugged in now for fear that it gets wrecked.

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Diseasel300 · #2 03-31-2018, 03:15 PM

There is a limit switch in there that stops the motor when the antenna is up or down. If it's failed, or the little mechanism that engages it is failed, the motor won't stop running.

SD Blue · #3 03-31-2018, 08:55 PM

Here you go:
https://www.ifixit.com/Guide/Disassembling+Mercedes+W123+Antenna+Motor/20902

ah-kay · #4 03-31-2018, 11:37 PM

Quote:

Originally Posted by Diseasel300

There is a limit switch in there that stops the motor when the antenna is up or down. If it's failed, or the little mechanism that engages it is failed, the motor won't stop running.

There is NO limit switches inside the antenna, the motor is stopped by current limiting electronics. If the antenna is at its limit, the motor will stop/stuck and current goes up. The electronics then cut the current after a timeout. There is nothing wrong with your antenna. You can check the theory by physically stopping it 3/4 mask or at any position and the motor will stop after a timeout.

My Stuff Owns Me · #5 04-01-2018, 12:10 PM

Quote:

Originally Posted by ah-kay

There is NO limit switches inside the antenna, the motor is stopped by current limiting electronics. If the antenna is at its limit, the motor will stop/stuck and current goes up. The electronics then cut the current after a timeout. There is nothing wrong with your antenna. You can check the theory by physically stopping it 3/4 mask or at any position and the motor will stop after a timeout.

I am pretty sure that the older ones had mechanical switches and the newer were electronic.

There could be something wrong if the noise he describes lasts for more than a few seconds.

Diseasel300 · #6 04-01-2018, 12:17 PM

Quote:

Originally Posted by ah-kay

There is NO limit switches inside the antenna, the motor is stopped by current limiting electronics. If the antenna is at its limit, the motor will stop/stuck and current goes up. The electronics then cut the current after a timeout. There is nothing wrong with your antenna. You can check the theory by physically stopping it 3/4 mask or at any position and the motor will stop after a timeout.

I haven't had the one apart in the SDL, but the one in my SL does INDEED have a limit switch. Perhaps there are variations out there.

Rick76 · #7 04-01-2018, 03:58 PM

He doesn't mention if it is the '87 300TD or the '84 300D.

zu! · #8 04-02-2018, 10:23 AM

Quote:

Originally Posted by Rick76

He doesn't mention if it is the '87 300TD or the '84 300D.

Hi Rick, it is the 87 wagon. Sorry for not being clear. Sorry for the late response folks...’‘‘tis Easter after all.

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zu! · #9 04-02-2018, 10:25 AM

Quote:

Originally Posted by My Stuff Owns Me

I am pretty sure that the older ones had mechanical switches and the newer were electronic.

There could be something wrong if the noise he describes lasts for more than a few seconds.

Indeed it lasts forever, as long as there’s power. It got my attention only because I was spending lots of time at the tailgate fixing something else and it was really quiet so I heard it.

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zu! · #10 04-02-2018, 10:26 AM

Quote:

Originally Posted by ah-kay

There is NO limit switches inside the antenna, the motor is stopped by current limiting electronics. If the antenna is at its limit, the motor will stop/stuck and current goes up. The electronics then cut the current after a timeout. There is nothing wrong with your antenna. You can check the theory by physically stopping it 3/4 mask or at any position and the motor will stop after a timeout.

So if the electronics are shorted it will keep clicking?

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ah-kay · #11 04-02-2018, 11:33 AM

Quote:

Originally Posted by zu!

Otherwise, it works flawlessly, going up when the radio is on, and even follows the switch on the dash (for medium, high and off).

What gives? Is there some sort of switch inside to switch if off? I don’t want to leave it plugged in now for fear that it gets wrecked.

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What else you wanted? It's working. The antenna probably is slipping due to wear and tear. The plastic is pinched by a roller to go up and down. It takes longer to stop, this is all.

zu! · #12 04-02-2018, 11:41 AM

Quote:

Originally Posted by ah-kay

What else you wanted? It's working. The antenna probably is slipping due to wear and tear. The plastic is pinched by a roller to go up and down. It takes longer to stop, this is all.

So, it’s normal for the motor to still click and whirr when the antenna is completely down and the engine is off?

All I want is for it to be COMPLETELY shut off when the antenna is at full or down mode.

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ah-kay · #13 04-02-2018, 11:59 AM

You think the motor or electronic is still running when the antenna reaches it's limit? For how long, no time out, say after 30 seconds? Then the timeout circuit is not working. It will drain the battery.

My Stuff Owns Me · #14 04-02-2018, 03:01 PM

The only way to know is to take it apart and see.

zu! · #15 04-02-2018, 09:03 PM

Quote:

Originally Posted by ah-kay

You think the motor or electronic is still running when the antenna reaches it's limit? For how long, no time out, say after 30 seconds? Then the timeout circuit is not working. It will drain the battery.

Yes. That’s what it’s doing. It hasn’t drained the battery yet...it’s not like running full-on. More like clicking and whirring...then stop. Then start again I would say 3 seconds at a time. But it never stops until it’s unplugged.

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