|Last modified 2005 APR 07 04:40:27 GMT|
This is the initial draft of some notes on repairing Hirschmann antennas.
The insides of the motor are the same mechanically between models made for Jaguar, BMW, and Mercedes-Benz (and no doubt a number of other European models, including VW and Audi) - so if you find an 6000EL at a scrapyard, you can swap insides with the one in your Jaguar. Electrical connections, as well as the plastic housing, differ, but these generally aren't broken on your original aerial. Hirschmann no longer produces the 6000EL, having superceeded it with a different model, of which I am awaiting confirmation of the part number - tentatively, I believe it to be the Auta 6000 KE F/10. Parts are still available, but pricey.
If you go to order a replacement aerial, you should note the number on the very top of ball on the end of the mast - there's a stylized 'h', with a two digit number below. On the Jaguar masts I've seen, it's always been "04".
The wiring to the overload module (the PCB mounted inside the aerial box, just above the motor) on the Jaguar is shown. When viewing from the end where the wires connect, with the PCB on the bottom, component side up, the wires are, starting on the left: BROWN (GND), BLUE (+V = UP), RED to motor, GREEN to motor, BLACK (+V = DN). The wires to the motor are polarized: RED+/GRN- = UP, RED-/GRN+ = DOWN. The BMW unit shown has a different wiring harness, with the following BMW-to-Jaguar conversions on the connections to the overload module: BLACK=BROWN, WHITE=BLUE, RED=BLACK.
Note that the Jaguar model has the electrical plug situated at the top of the housing -- if your aerial grommet deteriorates, and water enters the bodywork on the OUTSIDE of the aerial, it stands a good chance of pooling up on the top of the aerial housing, and probably entering around the base of where the electrical connector slips on. Besides the obvious suggestion to replace the grommet whenever it shows signs of deterioration, there are two things you can do to lessen the chances that you'll suffer a PCB fry due to water intrusion. The first is to get a bead of silicone sealant around the electrical plug, to reduce the amount of water intrusion. The second is to get a piece of mylar and drape it over the PCB and motor, so that (hopefully) the majority of water entering the aerial housing will flow off to the bottom (where the drain hole is), without contacting the electrics. If you look at the photo above and to the lower left, you'll see the area on the PCB has a "rusted out" sort of appearance - that's water damage, and one of the 1/2 watt resistors on the PCB is actually blown as well. The motor below (not shown in its entirety also had rust deposits on it, so I extracted that, used a stainless steel wire brush to clean it off, and then hit it with a dose of paint, which is why in the photo at the bottom of this page, you see a green motor.
In examining the assembly to determine why it wouldn't move the aerial mast even though the motor was running, I determined that a plastic tab on the inside of the clutch assembly had broken off, thereby causing the gear half which contacts the motor to spin without engaging the gear half which contacts the toothed nylon cord from the mast.
Effecting this repair was fairly easy. I first located a small screw which had enough bite on the interior of the broken tab, then used a dremel bit to carve away just a small bit around where the head of the screw would be on the topside of the clutch. I mixed a dab of 5 minute epoxy (about a pea sized worth), daubed some onto the broken face of the plastic tab, then threaded in the screw, adding some epoxy to the inside of the tab housing (which was hollow to start with).
If your Hirschmann antenna fails to operate, you might consider COMPLETELY disconnecting it electrically until it is fixed. Why? Because chances are, the unit will produce an unwanted parasitic drain, killing your battery.
There are several potential causes of mast failure (outside of a motor failure, which would present with no sound, a clutch failure as described above, or a PCB failure). Before getting into them, let me point out that you should generally remove the mast to work on it. If you remove the nut at the top and run the motor UP, the mast should eject (even if the mast itself does not extend), OR, you can remove the motor temporarily, and pull the mast out manually. When exercising the mast, a short length of 3/16" ID vinyl tubing is very helpful - just pass the toothed nylon cord through it, and situate it at the base of the mast housing (use tape to hold it there if necessary). This will keep the teeth from catching on the metal mast housing when you exercise the mast.
One method of mast failure is that it has been bent. Sometimes you can bend them back - but you need to be gentle or you'll kink the aerial, which you can't fix. A rigid tube just large enough to insert the aerial into can be helpful here. The second cause is oxidization of the mast - say where some chrome has scraped away and the mast has been exposed to the elements, and the mast has not been periodically lubricated. If you can exercise the aerial, you mgiht be able to work the spot out. I've found that superfine steel wool or wet sandpaper lubricated with WD40 (yes, I'm aware that WD40 is not a lubricant, but it works well enough for this particular purpose here), will scrub away debris without scuffing up the mast. Exercise the mast thoroughly, clean it off (while extended), then lubricate with some white lithium grease - work it in, and then gently wipe it off, but not too thoroughly. A third cause of failure is that the toothed nylon cord is broken, which would probably manifest itself as an aerial that will go up (if perhaps in a haphazard fashion), but will not retract, even though you can hear the motor running.
This is a shot of the collection of parts of the clutch assembly (with the gear, pictured further above, assembled and in place).
Lastly, a shot of the re-assembled insides of the aerial housing.
Sean B. Straw
EMail to: Sean.Straw+Jaguar@mail.professional.org