Replacement of Antenna Mast

The power antenna on my 1987 420 SEL started coming up only 8 inches or so, so after reading some really simple instructions online I decided I could probably replace it myself, and for $30 I could afford to risk disaster.

To find out if I needed a replacement with a toothed or a smooth tail, I unscrewed the collar and turned on the radio and pulled up on the antenna as it was coming out, per directions. At first it would not come out, despite several tries. I finally had to pull the tail pretty hard to get it out, and I MAY have snapped the end of it off inside the power unit -- not really sure. The tail seemed a bit short once I got it out. The end of the tail didn't look frayed or snapped, but rather cut at a 45 degree angle.

After determining that it was a toothed tail, I attempted to reinsert it into the power unit, intending to use it just to block the hole until the new one arrives. But the tail would never catch. I could hear the antenna motor running but couldn't snag the tail in the gear. Is this normal -- once out the old one won't go back in?

I've never done this little repair before. It sounded like any jerk could do it, but I'm wondering if this particular jerk (me) has screwed it up right on the starting line. Any tips? Any comments? Is there a broken-off piece of nylon tail in the power unit now?

Anyway I ordered a new mast via mail -- A Hirschmann 1105 mm with toothed tail.

Would a person such as I, with little to zero experience on autos but who can build computers from scratch, be able to install a new power unit if the new mast tail won't catch? Looking at the power unit, its replacement looks pretty straightforward.

Or could the power unit be taken out, opened up, and the piece of nylon removed (assuming there is a broken piece in there)?

Thanks much for any tips.

Tom Miller (wondering if he should have ever gotten into this)

One of the wires will be hot when you turn on the ignition switch. It powers the antenna. The other will be hot only when the head unit is operating. It controls the up/down switching.

:-)) My cars have the older Hirschmann, the Auta 6000u. It has a metal body with phillips screws holding the lid on. Really, I know very little about the Auta 6000el.

If you look at the pdf diagram Antennaworld lets you download from their site

), you can really strip these units down to their basiccomponents to clean them out. Dirt and corrosion are the things that causethem to malfunction, and I'm convinced that the problem is almost alwayswithin the mechanism -- not the mast -- when they stop working right. Thoselittle antenna motors have a LOT of torque. Plug it in with the face placeremoved and play with it for a while. A little crud on the mast isn't goingto stop these units from operating when it's working right. I've had onefreeze up in winter, but I'm not sure it was in optimal working order.Again, I'm writing in reference to the 6000u, but I'm assuming Hirschmannimproved the later version and didn't make it weaker.

A seized tension roller is one of the primary causes for failure on the older 6000u model. Again, my knowledge of the 6000el is limited, but if I were working on one I'd be damn sure the tension roller was in top working order. Buy a new one if you have to. It keeps the "tail" in contact with the drive gear. If it seizes, the drive gear becomes a rasp against the nylon driveshaft. If it doesn't provide adequate tension, the shaft is free to slip aginst the torque of the drive gear.

Make sure the tension roller is doing its job, and make sure the little drive belt between the motor and drive gears (4.021 on the antennaworld pdf image) isn't in need of replacement. The correspondence I've read on the

6000el suggests a bad drive belt is not an uncommon problem.

Tom -- look again at the pdf. A C clip here, a couple screws there and it's apart. It needs to be cleaned out and lubricated. A couple worn parts may need to be replaced. This is the joy of vintage German machinery: it CAN be dismantled, repaired and reassembled.

Good luck Russ

Not sure if this is why your antenna won't come up but I had the same problem. My antenna would not come up/down. I oiled but it did not help until I realized that the antenna was slightly bend so carefully I bend the antenna in the places it would not come down. This takes a bit of eye-judgement. Just lower the antenna down while turning it to see where it is not straight; the antenna will swirl slightly when not straigt while turning it then just bend it the opposite direction until straight.

Then clean and oil the antenna.

allot of work for a very inexpensive part.

Take 3 minutes!

New antenna is aprox $100 in Denmark. Work is aprox. $150

Total $250.

If it is just bend then do as mentioned - works and saves $250 in 3 mins.

Thanks for the response. However, the old antenna wasn't bent, just stuck for unknown reasons. I couldn't even pull it out while it was rising under power -- it got to a point and then stopped.

In any event, it's all moot now, as I took it out and cut off the tail so I could use the stub as a "stopper" for the hole while I am waiting for the replacement.

Tom

Ok. Mine did not look bend at all. But it was. Bending as little as 0.5 degrees pr. half meter - which is not visible to the eye but the motor can not push/pull the metal antenna when VERY slightly bend because the metal touches metel (the pole inside the smaller/bigger poles) and can't go up/down.

I hate to say this, but are you sure the antenna switch on the dash hasn't accidentally been pushed to the half-up position.

Paul

I understand what you're saying, but this one seemed to be snagged. I think there must be part of the tail left inside the power unit. Time for some trunk diving to get the unit out I guess. Thanks again for your comments.

Tom

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Yeah, it helps a lot, and many thanks. I have already looked at the drive unit in the trunk and it looks like I can get it out without destroying the car. I can't figure out how to open it up, but maybe that will be clearer when I get it out. Are there screws in the back? Clips somewhere? Or do you just pop the cover off?

Tom

Nah. I figured that one out a few years ago. First thing I checked.

Tom

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Well, I removed the power unit and cracked it open. Simple to remove: just unscrew the single bracket, pull the mast "protection tube" out of the little gasket that runs through the fender, unscrew the grounding wire (earthing wire) at either end, unscrew and unplug two additional wires (one goes to the radio and one into the auto wiring I assume, but I don't know which is which) and you're done.

The cover is held on by a number of little tabs and by putting a small screwdriver into each one and prying back gently on the tab you can loosen them one at a time until you can take off the cover. I only broke the very last one.

Inside, no remaining part of the nylon tail that I could see. Might be way inside I suppose, but if so I'll deal with it if the new mast won't go in.

I cleaned it all out as well as I could with an electronics solvent. Lots of junk inside.

Then I decided to try to put the old nylon tail down the mast cover and into the gears with the cover off to see what might be going wrong. The only thing I could figure out was that the nylon tail simply never would get past the entrance to the channel leading to the gears. I removed the mast "guide tube" and looked though it, thinking that maybe a piece of nylon was somehow jammed inside. But nothing. It just wasn't getting past a nylon collar leading into the channel.

Then I tried the other end of the nylon tail, which was not curved as much as the end I'd been trying. It went right through the collar and into the channel just fine, and as I turned the belt with my finger it caught without a problem. Then I tried the curved end again, but no go. I bent the curved end back so it was much straighter and it slipped right in without a whimper. I guess there is some place in this collar that snags the tip, although I could not see it with these fading eyes.

So the trick is to bend back the last 1 - 1 1/2 inch or so and it will slide right into the gear assembly.

Now to wait for the new mast and see if it will work. The teeth on the gears look fine, by the way. There is a tiny metal guide wheel called a tension roller that seems a little worn, but it doesn't appear to do anything except hold the tail against the gears. It is unpowered.

So what was causing the old mast to rise only 8 inches or so? I still have no idea. I presume the teeth of the nylon tail were too worn to grip the gears. Or maybe dfgdf's post about the mast being slightly bent is on target (although it doesn't seem so now that the mast is out. It slides up and down very freely without snagging, and it was the tail that snagged when I tried to remove it).

Or maybe there really IS a length of the nylon tail still deep inside the mechanism that I cannot see. Hope not, as disassembling the thing without breaking something will not be fun.

Tom Miller

I'm pleased if any of my advice proved helpful, Tom. Of course, you could always go on eBay, buy an aftermarket Hirschmann for $35 or so and sell the one you have for parts, but there's something appealing about keeping an old piece of machinery alive.

Cheers, Russ

It's seized. THey do that. To stop the new one from doing it wipe it weekly with silicone spray per the manufacturors recommendations.

You might be able to unstuck it by soakig the ehtire shaft in penetrating oil for a week then freeing it up with a bit of force, ie, a hammer. If that proves ineffective you can always beat the living shit out of it with the hammer since you have it right there.

| Yeah, I have the pdf and I can see exactly what to do. I've actually already disassembled it part way to clean it out. Whether or not I actually WANT to get into all the nooks and crannies is what's holding me back. I have visions of the thing exploding into all its parts while I'm trying to disassemble it. And that torsion spring worries me. Frankly, the electronics solvent worked pretty well, both gears are turning smoothly, and there is minimal crud. I put the old tail back into the slot and rotated the belt by hand and it slid right down into the channel without any hesitation and came back out the same way. Of course, there's no antenna to push. The belt looks pristine, like it might have already been replaced. No sign of slipping when turned by hand.

I'm going to reinstall the unit when I get the new mast and see if it works OK. If not, then I'll go further into its guts.

And I already ordered a new tension roller yesterday, and I am going to replace the old one. The old one rotates just fine, but it looks a little worn.

By the way, most of the parts on this thing are nylon, so I don't think that corrosion is much of an issue. Yours may have more metal parts.

You've been a great help, Russ, and I really appreciate it (as well as the suggestions of others). There are scores of old posts about this, but almost all of them just stop at the standard "removing and inserting the nylon tail" instructions.

Tom

Of course, you could

I'm not sure if this is the original or not, but it's been fun so far messing with it. Thanks again.

Tom

The current status of my project is that the Hirschmann antenna mast replacement has arrived and looks just fine -- it is absolutely the correct part. I have 2/3 dissassembled the power unit and cleaned it thoroughly by first spraying it all with electronics solvent, and finally dipping all but the electronics section in a bath of naptha. Amazing how much black junk I got out.

Now I am waiting for the replacement tension roller from Antenna World which had to be backordered but now is to be shipped tomorrow or the next day. This little metal wheel is the size of a button, costs $14 + shipping, and is definitely holding up the job!

Stay, er, tuned.

Tom Miller

More on the Never-Ending-Antenna Saga: I received the wheel and installed it. I completely dissassembled the gears and made sure there was no piece of nylon tail broken off inside. I then reassembled it all and installed it in the car and tested it with the cover off to make sure everything worked. Then I went to install the new antenna mast, but it would not pull into the power unit. I could slide it in, but it would not pull in, even though I could hear the motor turning.

I removed it yet again, opened it up yet again, dissassembled it yet again and happened to notice that a tab in the back side of the top worm gear was broken off so cleanly that one could not tell that anything had been there. The broken-off tab itself was tucked into its slot on the lower gear, looking like it was part of the lower gear.

So the motor turns and the top gear turns, but it would not turn the lower gear because the tab on the top gear that drives it was broken off (the tab does not show in the exploded diagram). It is the lower (back) gear that actually engages the nylon tail.

I have ordered a new gear. $24 and not instock.

Thinking I might patch the broken gear together so it would work while waiting for the new gear to wend its way towards New Jersey, I took a tiny brass sheet metal screw and actually repaired the broken tab with it, drilling the screw through a hole in the gear and into the (hollow) end of the little tab. It actually holds up well.

I then reassemble the unit (which I can now do in my sleep) and -- leaving the cover off -- test it in the car again. It runs and the gears turn. I then snap on the cover and slide in the nylon tail of the new antenna mast and it takes up smoothly.

Elated, I then screw down the chrome top nut and turn on the radio to check the job.

It comes up about 8 inches and stops, just like it did at the beginning before I fixed anything!

So after around 8 hours of work I now have a squeaky-clean Hirschmann "Auta 6000 EL" with a new tension wheel ($14 + shipping) and a new antenna mast ($29.00 + shipping) that works exactly the same way as it did when I decided to fix it.

Clearly it is possessed. But I will not quit.