Power antenna motor keeps running for a while

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Marc
250s
Posts: 272
Joined: Sat 30 Oct, 2010 9:20 pm
Model you own: w108
Location: Sydney

Power antenna motor keeps running for a while

Post by Marc » Mon 29 Apr, 2013 11:11 pm

Hi Team,

My W123 has a power antenna, which is in good working order. The only thing is, when I turn on the radio the antenna motor extends the antenna and keeps running for about 5 seconds after the antenna is fully extended. Turn the radio off and the motor pulls the antenna in and you can hear the motor running for a while after the antenna is fully down.

I am worried that this behaviour wears out the motor or antenna. Does anybody know if there is an adjustment on the motor to decrease the amount of time the motor operates once activated?

Thanks in advance for your comments and suggestions.

Marc.
280SE 3.5 - 1972 (Sofia)
280E - 1984 (Linda)
B180 CDI - 2007 (Diana)

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markb
300 SLR
Posts: 1729
Joined: Wed 20 Jul, 2005 1:54 pm
Model you own: w123
Location: Melbourne, Australia

Re: Power antenna motor keeps running for a while

Post by markb » Tue 30 Apr, 2013 7:10 am

Do you hear the crutching or nashing sound of plastic gears ?
If so is most likely that a replacement mast has been installed and the length of the 'toothed' plastic inner is the wrong length or your original plastic inner's teeth are worn.
Current Fleet
1985 C123 280CE Midnight Blue with blue MB Tex (234k klms, Daily Driver 2010- )
Past Benzes:
1972 W108 280SE 3.5 White (2002-2003 project)
1971 W108 280SE 3.5 White (1999-2006 Unmolested original & sadly missed)
1987 S124 230TE Diamond Blue (2002-2007 Family cruiser)
1983 W126 280SE Champagne 106k Klms (Custodian in 2013)
1969 W113 280SL Champagne (Custodian in 2000)
1988 W124 300E Diamond Blue (2016 project)

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Marc
250s
Posts: 272
Joined: Sat 30 Oct, 2010 9:20 pm
Model you own: w108
Location: Sydney

Re: Power antenna motor keeps running for a while

Post by Marc » Tue 30 Apr, 2013 9:05 am

markb wrote:Do you hear the crutching or nashing sound of plastic gears ?
If so is most likely that a replacement mast has been installed and the length of the 'toothed' plastic inner is the wrong length or your original plastic inner's teeth are worn.
Mark,

No sound of plastic gears. When I turn the radio on, you hear the motor raising the antenna, after the antenna is fully raised, you just hear the motor going. Same thing when turning the radio off: the antenna motor engages, the antenna goes down. Once fully down, you simply keep hearing the same sound of the antenna motor.

This lead me to think that there may be an adjustment to shorten the amount of time the motor operates...?

Marc.
280SE 3.5 - 1972 (Sofia)
280E - 1984 (Linda)
B180 CDI - 2007 (Diana)

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pastelgrey300D
OZBENZ Admin
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Joined: Wed 07 Feb, 2007 9:17 am
Model you own: w111
Location: Adelaide

Re: Power antenna motor keeps running for a while

Post by pastelgrey300D » Tue 30 Apr, 2013 10:39 am

There are no limit switches in these antennas, there is a plastic cog that turns about 1/6 to 1/8 of a rotation for every one rotation of the antenna winding wheel. Once this plastic cog has completed a full rotation it hits a pair of contacts and this is what shuts the motor off. They are designed to have a degree of slip and there is a spring loaded wheel inside to keep pressure on the antenna cable but also allow it to slip - but the antenna shutting off should be more or less at the same time as the antenna reaching its fully retracted position.

There are a few things you could check:

Is the antenna fully extending? Once it is out can you pull it out further by hand? If it has been bent or jammed or if it is corroded, one of the segments may be stuck and thus an antenna that is not fully extending will take less time to retract (again the mechanism will slip if it gets enough resistance - I had this on my 450SE where the mast had been bent and then bent back and it tended to jam until I cleaned and lubricated it). Try cleaning it with metho and lubricating the mast with a light smear of petroleum jelly (vaseline). The mast should be smooth and shiny, if it has corroded, try sanding it with 2000 grit wet and dry abrasive paper and then lubricate. Also is the correct mast type fitted? These antennas have a really long mast, they extend quite high (this is so you can still pick up AM stations in the middle of nowhere).
David
1967 W111 230S - Horizonblau
1965 W110 190c - Mittelrot
1967 W110 200D - Weiss (work in progress)
+ other classics

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Marc
250s
Posts: 272
Joined: Sat 30 Oct, 2010 9:20 pm
Model you own: w108
Location: Sydney

Re: Power antenna motor keeps running for a while

Post by Marc » Tue 30 Apr, 2013 1:38 pm

Thanks for the suggestions, I will have a closer look, investigate some more and report back :happy3:

Marc.
280SE 3.5 - 1972 (Sofia)
280E - 1984 (Linda)
B180 CDI - 2007 (Diana)

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Hendrik
Mercedes Demigod
Posts: 5497
Joined: Thu 28 Jul, 2005 11:33 am
Model you own: w124
Location: Hawthorndene SA

Re: Power antenna motor keeps running for a while

Post by Hendrik » Tue 30 Apr, 2013 1:59 pm

pastelgrey300D wrote:There are no limit switches in these antennas, there is a plastic cog that turns about 1/6 to 1/8 of a rotation for every one rotation of the antenna winding wheel. Once this plastic cog has completed a full rotation it hits a pair of contacts and this is what shuts the motor off. They are designed to have a degree of slip and there is a spring loaded wheel inside to keep pressure on the antenna cable but also allow it to slip - but the antenna shutting off should be more or less at the same time as the antenna reaching its fully retracted position.
1984 should have the later Hirschmann with load sensor?

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Marc
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Posts: 272
Joined: Sat 30 Oct, 2010 9:20 pm
Model you own: w108
Location: Sydney

Re: Power antenna motor keeps running for a while

Post by Marc » Wed 08 May, 2013 11:08 am

Apologies for not getting back earlier, but it's been hectic at work.

Here's what I found. At first I wasn't able to manually pull the antenna further out, but upon further inspection, I found that I could pull out another full segment. I WD-40ed the segments and now I have 4 segments that extend and retract. Each segment is about 15cm long, making the antenna stand about 1.8m tall, measured from the ground. I.e. I nearly 1.9m and when I stand next to it, the top of the antenna sits at about eye level.

There is still extra noise coming from the motor as if there is a fifth segment it's trying to push out (or pull in). Can anyone confirm how many segments there should be?

I haven't had a chance to look at the actual motor to confirm if it is an original Hirschman and to possibly find a type number on there.

Thanks for all the help and suggestions so far!

Marc.
280SE 3.5 - 1972 (Sofia)
280E - 1984 (Linda)
B180 CDI - 2007 (Diana)

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