Replacement of Antenna Mast

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Ewwww...I'm starting to feel a little guilty of aiding and abetting, Tom. Good improvisation on the gear tab -- I've done some similar kludges on both my earlier Hirschmanns. Maybe you can still cancel the order for the the replacement gear!
Does the antenna shut off like someone threw a switch -- that is, no struggling and straining, it just stops? It could be that the switching mechanism is out of kilter. On the 6000u the switches look like a couple sets of distributor breaker points and are mechanically actuated by a small idler wheel. I had trouble with one set of switches that had become badly pitted (fixed 'em with a jeweler's file). That may or may not apply in your situation -- I confess I'm not up on "modern" cars like yours, and the Antennaworld pdf offers little detail on the switching mechanism.
If I may offer a suggestion, I'd study the mechanism and figure out what makes it start and stop. When the head unit sends 12 volts to make the antenna extend, how does that direct the motor to start pushing the antenna mast driveshaft? Then, what makes it stop -- a cam? some kind of torque sensor? Run it a bit with the cover off and watch it work. Watch your fingers if you poke around the workings with the antenna energized!
I've got an '87 Audi with a Fuba power antenna -- the design is brilliant, but prone to wear. I think I spent about $125 on parts to get that one running right. The Hirschmanns are repaired far more economically, I think (hope). ;-)
Cheers Russ
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wrote:

I can't really tell if it is straining or not, but it stops dead and you cannot pull it up or push it down. It could well be some sort of switch issue, but as far as I can see this function is entirely controlled by a circuit board and a few transistors. Nothing mechanical. I slid the circuit board out and looked at it under magnification, but can't really see much -- nothing to fix, that's for sure. Replacement is the only practical option.
The new antenna does seem to drag a little when I push it up the tube manually. I'm cleaning and lubing with silicone spray to see if this resistance is turning the drive off. I doubt it.
BTW, I am now able to get the mast to extend fully by turning the radio on and off quickly three or four times. This restarts the motor and pushes the mast a little farther out each time. So this would argue for the switch (wherever it may be) being the problem. It's as if the gear only goes part of the way around when pushing the mast outwards. However, it takes it all the way inwards with no problem.

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If you can't tell, then it probably isn't. If the motor/reel were encountering resistance, I think you'd hear it as a kind of stalling sound -- the pitch of the motor would drop as it comes to a stop
The standby repair for malfunctioning circuit boards is to reflow the solder joints. Clean off the lacquer covering the back of the board with paint remover, and have at it with a 25w soldering iron. If one of the joints has cracked over the year's then, you've facilitated a repair.
But it would probably be a wise idea to just operate the antenna as you are for now -- sometimes the antenna unit needs a little time to self-adjust to the position of the mast. Maybe it'll "heal itself."
I would be interested in finding out how the antenna "counts off" the number of revolutions the take-up reel makes before deciding to turn itself off. On the older Hirschmann there's a little "paddle wheel" idler that turns incrementally every time the take-up reel makes one revolution. On the back side of the idler are two cams, one to switch the motor on and one to turn it off.

I think you're right. The mast makes contact in the tube with a contact the antenna lead plugs into. That could produce a little drag -- but not enough to slow the antenna motor, IMO. They're quite torquey for their size.

Definitely a switching issue then. Works fine one way but balks on the uptake. Think of it this way: for every segment of the mast, the take-up reel has to go around once. Four segments equals 4 revolutions, more or less. The antenna is supposed to count four revolutions before shutting off. Right now it's only counting up to 1.
That's my impression from here, anyway.
Hang in there, Tom -- you're at least halfway through this problem, I think.
Russ
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wrote:

I ordered a new circuit board from Antennaworld ($60), along with a new mounting bushing (on the fender) as the old one has cracked as a result of me taking the unit on and off -- can't catch a break on anything I guess. Out of town most of next week, so we'll see how they work when I get back.
The motor makes no laboring noises when the mast is going up its 8 or so inches. Whirrs and just stops. When it comes down it makes a brief little squeal at the very end, leading me to believe that the timing or counting of the revolutions has gotten off kilter. No sign of any "counter" to be seen. I really can't think that this will somehow adjust itself, but I'll be trying it during the week.
Thanks for your comments Russ. Appreciated.
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Today I looked at the Auta 6000EL on my 560SL, which has a related problem. Only in my case the motor tries to push the antenna up too far. Sounds like 4 turns (Grind + big click for each rev). I cleaned the mast and looked inside the housing for any signs of damage but did not see anything obviously amiss.
So I think that the "counter" is off in the up direction and maybe the clutch is stuck. The "grinding" sounds like the drive gear slipping on the weed-whacker teeth. Seems to me that the clutch should just slip quietly.
At least on the 560 the mechanism is easier to get at than on the 350SL I useta have - the antenna mechanism on that is at the rear of the left front fender. To get at it, remove exhaust system- remove wiper motor- remove parking brake footpedal support- all to remover the cover plate for access to the mechanism, which was the older type with mechanical counter and switches.
Anxiously awaiting your story of thesuccess of replacing the elex board. I recall reading something about photocells used to count rotations but cursory examination did not reveal anything obvious.
LeRoy Dorman San Diego
Tom Miller wrote:

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On Mon, 10 May 2004 00:18:56 GMT, "LeRoy M. Dorman"

LeRoy, I'm still waiting for a new power controller board, a new worm gear (which is the gear that lifts and lowers the antenna by engaging the nylon tail on the mast) and a new fender bushing, all from Antenna World. For some reason they are not shipping the order and will not answer my emails to tell me why. I suppose the power board is on order or they are looking for one, but can't be bothered to tell me this. Odd.
Anyway, I don't know what is the issue with your Hirschmann, but I've figured out that this model does not have a clutch at all. I'm still not entirely sure what determines the number of turns, but the best guess I've come across is that it's simply a matter of the length of time the motor is on, and this is determined by the board. I don't think that there are any photocells. I'm also told that the motor has automatic overload protection built into it, so this may protect a motor from turning too long after the antenna hits top or bottom. It all does seem like a weak spot in an otherwise well designed unit, however. And who knows, maybe I'm wrong.
I would advise you to disassemble the unit and check the worm gear for a broken tab. This seems to be an issue that is not uncommon. Mine was broken (I think I broke it when taking out the old antenna mast -- I have temporarily fixed it by driving a tiny screw through the hole in the worm gear and into the hole in the center of the tab). This might make the gearing run on when the mast hits the top mark, yet be wedged in enough to turn the gear. And it might explain the clicking noise. Worth a look anyway.
The torsion spring inside the worm gear is there simply to connect it to the power gear, by the way. As far as I can see it has no other function. The reason there are two gears is that one has slanted teeth to engage the screw drive that the motor turns, while the other has straight teeth to grip the nylon tail of the antenna.
Here are some good comments about fixing the unit:
1. Exploded diagram of the unit showing most parts (but not all the sides, so be careful)
http://www.antennaworld.com/2004/departments/amfm/techinfo/mercedes/downloads/6000el.pdf
2. Forum comments on repair including a circuit diagram
http://www.mercedesshop.com/shopforum/showthread.php3?sK06c5bfefe0aa42dc2b494226ebd64d&threadid 103
3. Repair procedure for Auta 6000EL on a 300E (Note, this antenna unit is significantly different from mine as shown in a few parts, indicating that the 6000 EL has apparently been silently improved year to year or someone replaced the guts of the one on the web page with another unit).
http://www.davebarnhart.com/mb300e/antenna.htm
4. Forum discussion on how the antenna works and various wiring issues (good info here)
http://www.mercedesshop.com/shopforum/showthread.php3?sK06c5bfefe0aa42dc2b494226ebd64d&threadidp719&perpage &pagenumber=1
5. Thread on AntennaWorld forum about my own antenna problem. I got one good answer at least. Note Don Bryce's comment about fixing the grinding noise -- maybe this is your problem?
http://www.autoswitch.com/cgistuff/yabb/YaBB.cgi?board=amfm ;action=display;num82761360
Hope all this is helpful. I can now take the thing apart in my sleep and think I can fix it if I can ever get the parts from AntennaWorld. I'm also working on another source if I don't hear from them.
Tom Miller (spending his retirement becoming an unwilling expert on Auta 6000 EL)

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wrote:

Ah, but Tom, you're already sharing your hard-won expertise with another enthusiast. You've become a source of MB lore! People will be referencing your experiences in the Usenet archive for all eternity. Doesn't that make you feel kinda warm inside?? ;-)
Seriously, I will say that I've dealt with Antennaworld repeatedly and found them to be one of the best sources available for arcane parts such as these. They will come through for you if they can (and I think they will).
As for not returning your emails, that seems to be a Miami thing. I ran across a source for used air conditioning service equipment down there and ordered a vacuum pump from them. After two weeks of unreturned emails I was ready to file a mail fraud complaint to the USPS...but then the pump arrived, at a bargain price.
You still might want to think about reflowing the solder joints on the circuit board you have...check www.mbz.org archives for tales of similar restoration of the cruise control amp... in fact, you might also want to read a little treatise on the 6000el from Rich Sexton's site at http://vets.list.archives.mbz.org/1998/Nov/Vol_1_Num_474 /
Good luck Tom!
Russ M
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wrote:

Hmmm. "Warm" is not the word I'd choose :-) but it's true that I am stubborn about this stuff. I have a strange compulsion to beat this thing into submission. And because I spent much of my life writing a variety of scripts, ads, manuals, and brochures I also feel compelled to expound on it in great detail in this thread. I do indeed have the idea that others may benefit, although I'm not exactly looking for a Usenet monument. My 15 minutes of fame is long used up I'm afraid.

Yeah, they have an amazing stock of parts and they have been quite accommodating with other parts shipments so far. I think they will come through too, but it is frustrating not knowing if they have even viewed the order or not.

I am thinking of pulling the unit again and at least checking the power unit more carefully. I'm a pretty clumsy fellow and not sure if I am up for reflowing the joints.
Thanks for the pointer to the Rich Sexton site. His comment about a "solid-state transistor driven load-detect shutdown, along with drive wheel spring-loading to allow a slight over-run" pretty much explains how the unit decides when the antenna is up.
Tom Miller

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On Mon, 10 May 2004 15:48:33 GMT, snipped-for-privacy@xxoptonline.net (Tom Miller) wrote:

Just a quick follow-up on the AntennaWorld thing: I got a very nice email from their customer service telling me that they were waiting for one part (the worm gear -- they should have it in two/three weeks) and will ship everything together when they get it. Can't complain about that.
Tom Miller
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|

Just to finish off this thread (or is it finished? Time will tell), I got the worm gear, the fender bushing, and the new power controller board from AntennaWorld yesterday. I went out late this morning to remove the unit and install the new parts.
I loosened the chrome nut on the tip of the antenna mast to free it from the unit so I could remove the unit from the inside rear fender -- the nut, a collar really, is part of the antenna mast, not a separate piece; the mast slides up and down inside the nut. But for some reason it would loosen but not release easily, and rather than force it I decided to raise the antenna slightly to take the strain off of it. When I turned on the radio, the mast just chugged right up to its entire length! In other words, the unit was working just fine. I tried it several times and no problem. Go figger.
I did remove the unit anyway and installed the new worm gear, figuring that the original, broken one I repaired would not last long. And I replaced the fender bushing (heating it up in hot water and greasing it up a little made it a simple task). I reinstalled everything and it still worked fine.
So my diagnosis is that either loosening the nut on top of the fender allowed the mast to slide more easily, enabling it to go up. Or the power controller was out of sync and it eventually got back in sync through some mysterious and magical effect known only to Hirschmann. Or there was a loose connection on the board that jiggled back into place. Or there was a corroded connector to the board that got cleaned off by removing it and replacing it a number of times (I did clean all the connectors on the top plug with an electrical solvent this time).
Anyway, if it ain't broke, don't fix it. I do think I will keep the new board in case this is just some electronic fluke and it breaks again. I can afford to be a sport for $60. I figure it will break again eventually anyway, and by then there may be no more parts available.
Kind of disappointing in a perverse sort of way when things seem to fix themselves, but ....
Tom Miller
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wrote in message

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Tom, forgive me, smug bastard that I am, I PREDICTED that the antenna would self adjust. I'm of the school that unit found its sweet spot. You've worked with it for awhile now -- do you honestly believe that a sticky mast would defeat that motor? It'll mangle your digits if you aren't careful.
Next: how good a craftsman are you? (Judging from this exchange I'd guess you're pretty capable.) If you fixed the original worm gear to your satisfaction, I'd send the replacement back to Antennaworld or at least save it and the circuit board in your valuable stash of rare vintage antenna parts. I bet the simple fix you made will work for years. Why waste it?
As for the disappointment inherent when things fix themselves, consider the daunting environment the Hirschmanns operate in -- they have to make adjustments to survive. Our humble role is simply to help them along
Congratulations! Russ
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wrote:

Yes, you did indeed predict it -- can't argue. And the motor is powerful. But it would be nice to know why it suddenly sync'd after a couple of weeks of turning the radio on and off. I mean, why now and not earlier? After I cleaned it all out and replaced the mast and the little tension wheel I ran it up and down a number of times -- maybe 20 or more. Then my wife drove the car daily for several weeks, using the radio frequently with the mast at half staff. But no joy.
Then after several weeks, it suddenly works.
I'd actually put my money on another prediction of yours, that a circuit or connection or solder joint on the board was cracked, and that I should reflow all the soldered connections (which I did not do). I figure that a cracked joint or a soldered wire has jiggled back into place.
But who knows?

First of all, it's already replaced. Secondly, although the new worm gear cost me $24, I have no confidence that the old one I fixed would last long. I simply ran a tiny screw through a hole in the broken worm gear and into the tab, and although the repair is solid now, it is not fixed well enough to last long. And no ordinarly glue would hold this tab. It would either take some particular glue, which I would have to find by trial and error, or it would have to be "welded" with a soldering iron -- which I am not sure would even work. Better to replace it and be done with it.

Now, now, Russ. I like the sentiment, but don't commit the "pathetic fallacy." It's just a machine! ;-)
[pathetic fallacy -- NOUN: The attribution of human emotions or characteristics to inanimate objects or to nature.]

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.

True, could be cracked solder -- the unfortunate thing about the switching device being solid state is that you can't observe its function visually. My theory on the earlier 6000u is that the switches permit the motor to overrun the limits of the driveshaft slightly; a clutch in the takeup reel prevents any damage. As a result, it makes a momentary dragging noise after it retracts -- or, if the mast is misadjusted so it doesn't retract all the way, pulls the mast in gradually until it's right. But that's not really what happened in your situation, is it.
At any rate, the answer will become evident eventually. If it's a cracked solder joint, it'll malfunction when vibration and the elements have their way. I'm rooting for the self-adjustment theory! Then again, can always replace the circuit board, so what the hey.
As for that other point, I admit I can't really imagine removing a good part and replacing it with a jerry-rigged one either. Guess that was my second bottle of Spaten Optimator doing the talking.
I have found that these antennas sometimes require the spit-and-baling-wire approach, though, and actually function fine with some improvised parts. That's a necessity with the older units, where a lot of the stuff is NLA.
Anyway, It's been entertaining and interesting being a spectator to your antenna repair, Tom. I've learned a few things in the process, too -- including the definition of "pathetic fallacy!" Good luck to you.
Russ
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