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Question on 740 power antenna:

Its my 92 740 turbowagon. The antenna was gone, snapped off at base. I bought a new antenna and installed it. The plastic track to make it go up/down went in OK. However, the motor doesn't work, so I just installed it extended. I opened up the panels and to my surprise I found that the motor isn't electric...its a vacuum operated motor with two lines going to it. SO I started the car and tried it.... with the dash switch in either position, there is no vacuum on the clear line (the black one doesn't come on/off with a barb fitting like clear one does). My guess is that the switch is not electric at all either but its a vacuum switch. Haven't torn into the dash to check that out yet. Anyway, how to troubleshoot where the vacuum to operate the antenna is being lost?

Thanks, geronimo

Reply to
geronimo
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Vacuum? That's weird, I know for a fact the '87 antenna motors are electric. Sure you're not just looking at the moisture drain?

Reply to
James Sweet

Hmm......maybe? I am seeing the bottom of a metal cylinder abt 1 in wide, and there is a black 3/8 plastic tube (or cable), as well as simiilar size clear tube, both connecting to the bottom. Guess I will look closer at that black tube and see if its maybe actually an electrical cable. Its like permanently sealed to the bottom, with no sign of connections on outside. You're probably right, the clear tube must be a drain, and inside the black tube/cable there are probably wires. I have checked for a blown fuse for accessories and none were blown.

thanks, Geronimo

Reply to
geronimo

In the wagon, the motor and spool assembly is located in the lower area down below the window and drives the antenna mast through a cable enclosed in a plastic sheath similar to a bicycle brake cable. What you're seeing is the sheathed cable and the drain tube which run down to the motor.

Reply to
James Sweet

YOu got me on the right track alright. Pulled up that side floor panel and there it was. There is a control module for the motor, and when I opened it up, I see the very bottom edge of ithe circuit board got immersed in water, and shows massive corrosion. Good news is that the only semiconductors on board (other than power supply diodes) are two

7400 QUAD NAND ICs. I think I even still have some of them in my electronic junk box. Shouldn't be too hard to repair the PC board. I tempirarily cut sires to the motor and touched to power/gnd in both polarities, and the antenna goes up/dn just fine....so a new or repaired module is definitely what it needs. Thanks, Geronimo

Reply to
geronimo

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