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Hello Class,

Today we are going to tacke rebuilding the Hirschmann Automatic Antenna. The Hirschmann comes in two flavors, Semi-Automatic and Fully Automatic. The Difference? That "ANT" switch up front that takes command of it and stows it or makes it go to "Half-Mast".

Why is it important to know the difference? Well Duh! It's MB and everything is different from car to car even when they are the same.

When I did my restoration, I did not know the diff at that point and the one on my car had a bent mast and so I just bought anouther used one off eBay which was in good condition and is in my coupe now. Since I had the car apart and I had a spare switch, I wired two extra wires, routed out the change cup for the switch and I was done. However, with the impending "Rear Sun Shade" installation, I need the two wires already laid back to the antenna for the shade control, plus of course the switch position itself. I had, when I did the antenna switch hoped that one day I would find a rear shade. Then Snibble came through with a GREAT DEAL and I scooped it up and it's on it's way now.

So I went to the junk yard and found the remnants of a fully auto ant. With a FAA, it has three wires basically. Brown for Ground, Red for power connected to a constant hot and that is to retract when you turn the key off. And Blue is the +12 trigger to command it up by the radio. This is connected to the Radio's "ANT" wire. The other two wired in the old style commands "Half" and "Down" on each wire. Not needed since I have a DVD/NAV system that commands the antenna only when the Head unit needs the signal.

The Sedan had a very new looking one that was the old style, but the case was in VERY good shape. So I opened it to look inside and it's gears were broken. The antenna has a weakness, rather safety that is it's Achilles heel. More on that later.

So I had a good electronics package from the one from the JY and I had a clean unit from the sedan, now to make them one.

First off take the antenna out. If you don't know how to do this, stop now. Do not go farther...

Next, You have to open the unit. Do it gently bu getting a couple of your little screwdrivers out and GENTLY prying the tabs in and up. Once you get one or two done get another LSD (Little Screwdriver) and slide it under the flat way and work out that side. Once you get the cover off there are three rubber grommets, collect them and DO NOT lose them.

Unscrew the antenna at the top of the mast IF you still have a mast in that is. Once it is loose, then pull out on the mast and you will see how it unreels. Hold the reel down a little with your hand.Once the mast is out undo the set screw that holds the guide mast in and unscrew the guide mast. That is that short aluminum tube that comes out of the black case. Careful to note and and all grommets and seals. Mine had two. One in each of the inner guide tube.

In the first pic you will see the basic layout. Unscrew the two motor screws in the center of the pic. That will separate the motor drive from the plastic cable housing. If yours is black like this, that means that (Like most of these) the inner cable bearing has worn a flat spot. Inspect and clean the worm gear on the motor drive. Clean these with a mild solvent or rubbing alcohol 91% and a old toothbrush. Remove the old drive belt and replace it with the one from the rebuild kit. Ger some "White Lightning Grease" from the auto parts store of your choice and you will lube this gear when you reassemble.

At this point I remove the control unit out of the JY one (the FA) and swapped it into the SA one. The plug slid out easily and the new one went right in. The + and - wires to the motor had a very convenient plugs too. Thanks MB and Hirschmann!

So I swapped the controls and plugs and reinstalled it into the unit. This one did not require the cleaning that the older one would have, had I restored that one in the pic. The one out of my sedan was fairly clean, but did need a little TLC. So I again cleaned everything in Alcohol.

Part 2 next post.
 

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Part 2

Remove the circlip holding the round gear wheels. These are two geared wheels held together by a stud/tension spring affair. More on that later. Remove that gear assembly and set it aside as you will replace it completely. If you separate the wheels probably rattling around in there is the piece pictured. That is what catches when the antenna reaches it's up or down limit. It tensions in either direction to ease the limits. That cog is what usually breaks.

Pictured you will see the new and the old side by side along with the broken gear. In both of these donor antennas these were broken. Ensure that the spring is positioned properly and place the cog into that area where the spring ends meet. It should fit nicely together. Next is to replace the roller bearing before you put that back in.

So next unscrew the two small screws holding down the moon shaped bracket. Under there is a roller bearing which is most likely grooved from uneven wear. Clean it all out of the gunk that it is probably built up, Replace that cover if needed with the one supplied (I used my old one) and the pin and grease it in there and replace the bracket.

Now for the bottom. Turn it over and remove the bottom cable raceway and the guide pin. Clean that all up and reassemble and lube.

Now put the top gears in place ensuring that the gear with the spring goes on the bottom. Replace the circlip and bracket if it has one. Replace in the case making sure you replace the three rubber grommets in the bottom. These are IMPORTANT!!! DO NOT LOSE THEM OR LEAVE THEM OUT. You won't like the results.

Screw the motor back in place and lube it where it meets the gear wheel. Replace the guide tubes and tighten all that up.

Part 3 next.....
 

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Powerup and testing.

Okay, so you should have it all back together now except for the antenna. If you are sure of your work, check it all again and replace the three top grommets and put the cover back on. If you are brave and want to see it in action, you can leave the cover off, but BE CAREFUL as the parts COULD come out at you....

As for a power supply I use a +13VDC 2A "Wall Wart" from my collection over the years. Anything in the 12-14 Volts DC and from .5 amp up to 2 amps is good. No need to be exact as a cars alternator wavers slightly.

So if you are this far I assume you have the Electrical manual. I have a pigtail with the right plug and bare wires. So hook up the ground of the PP to the brown wire and then the red + side to the red wire. The motor will come alive in the RETRACT MODE. So unless you are quick, don't bother trying to feed the antenna rope in yet. Take an alligator clip and clip it to the blue lead (The radio control) and then touch that to the +12. That will make the antenna EXTEND. Leave it touching, the antenna will stay up.

Now get the new mast. Uncoil it and lay it out so that the cogs face into the gears. feed the rope in until you feel it engage the teeth. Now just unclip the blue wire and the antenna will retract. Be careful and feel it in until it stops. It should be snug and the limit should kick in. As it's feeding in, hold down the plastic housing with your hand to keep it down. Now you will see why the grommets are important as they do absorb the torque on the motor.

Once you are satisfied, put the top cover back on remembering to place the three grommets first. Screw in the mast at the tip and re-install in your car....

Check for proper operation.

I got my rebuild parts from La Jolla Stereo. Cleeves there was most kind. I got the replacement mast off eBay. The whole thing took me less than an hour.

I hope this helps.
 

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Slightly off my own topic and sure to get a thread of it's own tomorrow, My AMG rear spoiler got painted today and looks BEAUTIFUL and is set to get mounted tomorrow.
 

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La Jolla Audio

I have no affiliation to this company nor receive any interest from them.

I got the Antenna off eBay for $21.00
 

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Good stuff! Thanks!
 

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Mclare,

are you familiair with the BBC program Blue Peter?
It's a kids DIY program in which the guy presenting it frequently says "here's one I made earlier".;)
Good off you to share this info though. We need more off this. Especially with the pix..

gr J
 

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great write up.( as usual ) but iv been looking for a thread on taking the antena out, & replacing the grommets that seal it to body as mine have broken & possibly will leak. it looks like there are a couple of pieces ect. which i have no problem ordering new, but want to do the labor myself.
 

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great write up.( as usual ) but iv been looking for a thread on taking the antena out, & replacing the grommets that seal it to body as mine have broken & possibly will leak. it looks like there are a couple of pieces ect. which i have no problem ordering new, but want to do the labor myself.
The Grommet is easy to replace. There is a screw at the bottom of the antenna, and the grounding strap. Undo the connector first, then undo the antenna connection, then the ground strap, then the screw at the bottom. Pull the antenna down and out. Replace the grommet, then reverse the above procedure.
 

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great write up.( as usual ) but iv been looking for a thread on taking the antena out, & replacing the grommets that seal it to body as mine have broken & possibly will leak. it looks like there are a couple of pieces ect. which i have no problem ordering new, but want to do the labor myself.
This will not possibly leak - it will leak. And the water will find a drain hole, and if it can't find one, it will make one. I've seen it. Replace ASAP!

Sorry, but I have a rabid fear of rust, with good reason.
 

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I am rebuilding my antenna now and find that the worm gear is worn. Any ideas on a source for this part?
Well you can get it from where I got the rebuild kit. Did you try them?

http://www.lajollaaudiorepair.com

If not get one from a JY. I have the one you saw pictured if you need it.
 

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That is a hunk of junk. You will get what you pay for.
 

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One word: junk!
X 3 (absolutely).

I was just taking my apart last night and cleaning it up. While it was jammed, it does not look like I will need to replace any parts.
 

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The Grommet is easy to replace. There is a screw at the bottom of the antenna, and the grounding strap. Undo the connector first, then undo the antenna connection, then the ground strap, then the screw at the bottom. Pull the antenna down and out. Replace the grommet, then reverse the above procedure.
Thanks so much for this add.. I have been looking for these instructions in the forum and finally found out how to do it...I've lost the mast cable into my power antenna unit and need to figure out how to pull the thing out... now I'll give it a shot.
 

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Thanks so much for this add.. I have been looking for these instructions in the forum and finally found out how to do it...I've lost the mast cable into my power antenna unit and need to figure out how to pull the thing out... now I'll give it a shot.
Welcome to the forum.
Please click 'User CP' on the top toolbar and complete your profile with the car mod and location, to make it easier for members to offer advice.
The 'Welcome to the Forum' announcement / tutorial sticky on top shows how to take advantage of all the forum features.
Cheers
 
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