W123 antenna not fully down or up - PeachParts Mercedes-Benz Forum

rhodes2010 · #1 01-20-2006, 04:24 AM

I tried to check all the archives for antenna stuff first.

Once before I had done a new mast so knew it was easy.

Current antenna does not fully extend, or go all the way down.

1. I pulled out the mast and cleaned and lubed until it moved
very smoothly, seemed like little effort.

2. Pulled a power antenna unit from a donor car. Unit looked almost
new inside.

3. Installed power motor into car before inserting mast.

4. Noticed that with antenna switch "down" or off motor runs and stops.
But when power is on (antenna switch up) power motor just keeps
running and running and running. Like it did not have a top setting
or fully extended setting. This made me thing that it was controlled strictly
by resistence. It is a clutch style, not the belt version I had read about.

5. Used the standard mast replacement method of inserting white antenna
lead while hitting antenna down, fed right in, just not all the way down.
Do antenna up and it goes up, down and it goes about halfway.

6. So... I removed power antenna again, opened it. Thinking that it is set
at bottom of travel. I hold open a little spring clip and insert the mast
all the way into the motor body manually. Now I figure I am fully inserted,
bottom of travel, no problem.

7. Reinstall into car, turn on power, move antenna switch from down to up.
It does not fully extend, and when I go back down, does not fully retract.
I was suprised it did not go back down all the way, that's where it started.

I thought maybe the mast is causing enough resistence that it is signaling
the motor to stop, so a new mast might solve this.
But maybe the motor has some true bottom or top of travel and I inserted
the mast when I should not have.

Before I replace the mast, or maybe the whole unit - any one ever gotten
inside one of these ?

Thanks in advance.

Diesel Giant · #2 01-20-2006, 05:21 AM

Hmmm that may be a good idea for a pictorial.

rg2098 · #3 01-20-2006, 06:38 AM

Try adjusting the big gold nut on the outside of the wheel a few turns and see what you get. I had the same problem and I think playing with that fixed it.

rhodes2010 · #4 01-20-2006, 11:33 AM

That would be adjusting the tension on the clutch I suspect.

Tonight I plan to run the antenna motor with the cover off to observe
what it is doing.

beaulieub · #5 12-11-2007, 05:44 PM

I just had the same problem with my 79 SD. I found that with the radio on, the mast only extended maybe halfway. So, then I pressed the antenna UP button and the mast extended fully. When I turned the radio off, it only came down about half way. Again I turned the radio on, then pressed the UP button and finally got it to travel the correct distances when the radio goes ON/OFF.

Bert - NH