Hirschmann 6000EL Lo-buck refurbishment

[donbryce]

This is an update on a previous post that discussed some inexpensive ways to repair the 6000EL. Mine was suffering from the usual ailments: a broken/frozen/corroded mast, non-functioning circuit board, and a broken pin on the nylon drive gear.

Repair of mast: Replaced with a new one, found on EBay for about $20.00. More on that below. (Tip on opening the case: insert a flat blade screwdriver into each of the catches and twist, starting at the top and work around. This can be done in the car.)

Circuit board: I found a cheap copy of this antenna (Car Quest brand) and transplanted the circuit board. All the 6000 needs is the type of board that senses end of travel electronically, rather than a physical gear driven counter or limit switch. Many aftermarkets use this technology. The donor was about $30.00. The only connection is to the the original motor, 2 wires, plus a ground.

Drive gear pin: I used a tiny nut and bolt to hold the broken pin piece to the gear, with a crazy-glue like cement to bond the broken piece. This little pin is what pushes on the spring tang to provide some give at the end of the up (and down) mast travel.

The fixes worked fine for awhile, but then the antenna started making a grinding noise after it fully extended the mast, as if the motor was still turning something inside. This went on for about 5 secs, then stopped, and only on the up travel. Very annoying. I took it apart last night and found the problem: the replacement mast I put in is about 6" shorter than the original, so there weren't quite enough teeth on the nylon cord at the end of travel to catch on the gear. The sound was the teeth jumping out of the gear as it tried to continue pushing the mast up.

(This would have happened even if all the rest of the unit was original, and makes the point that you should always measure the mast length from the tip to the end of the cord and compare with the new one to be sure.)

Solution: I shortened the tube 1/4" to place more teeth on the gear. I took this off the threaded end of the outer tube, where it goes into the case, as well as off the inner guide tube. Works fine now, completely silent up and down.

So, you can use a circuit board from a similarly designed antenna to control the up/down of the mast, as long as the circuit is wholly capable of sensing end of travel without any external device or counter. The originals are no longer availble, except from specialty shops like Antenna World or Walter Odemer Co., and they are well over $100.00.

As for circuitry and connection to the Mercedes harness, all you need is a ground, an ignition switched 12V, and a 12V trigger from the radio or whatever HU you have. These are all in the plug to the original, and details posted elsewhere on the forum, so I'll not elaborate.

There's nothing quite as satisfying as a silently operating Hirschmann that cost less than $60.00 to renew (+ a few hours tinkering, which to me is it's own reward). Hope this info helps someone else.