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Antenna Fuse Location

Started by Rolo, 25 June 2023, 06:18 PM

Rolo

This was strange.  I'm one of the lucky ones that has a Hirschmann that still works fine.  I got a new mast from Mercedessource and the tail was long making it stick up an inch when full retracted.  Ken said to cut it down and after that I couldn't get it to feed despite tapering the cut end.  So I thought what the heck, I'll remove it, open it up, grease the worm drive and clean everything.

Here's the strange part.  When I unplugged the unit, it blew the radio fuse in the main fuse box.  I'm guessing the antenna fuse blew. too.  Can't find that fuse.  Anyone know when it's located?  It's is displayed on the FSM on both the main wiring diagram and the small diagram in the antenna section.
 It's the red wire fuse. Thanks

UTn_boy

The electric antenna gets is power from the radio or the separate power amplifier (only with Mexico, Grand prix models, and early Europa II Stereo models......up to about 1975.  Regardless, since the antenna gets it's power from the radio, the radio fuse IS the antenna fuse, as well. 

You'll have to go back and check your work.  These are very easy to stuff up if you've never been inside of one....a lesson I learned the hard way many years ago.  But with more time and practice they're easy to learn about. 

You obviously have a dead short to ground or something is drawing too much on that particular circuit, such as a bad antenna motor or the like (shorted armature, worn commutator, etc).  I realize the motor is probably fine, just using it as an example.   
1966 250se coupe`,black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3,papyrus white/dark red leather
1975 450se, pine green metallic/green leather
1973 300sel 4.5,silver blue metallic/blue leather
1979 450sel 516 red/bamboo

rumb

If you cut the end blunt it doesnt like it.  use a file and taper the non-notched side to a small angle and it will help get it to go in.
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,
'16 AMG GTS
'21 E450 Cabrio

Rolo

Thanks for the information.  The circuit diagram in the FSM shows two fuses.  With radio fuse replaced, it doesn't blow, but absolutely no power to the antenna.  But I haven't put a tester on the wires yet. I guess that's the next step.

Rolo

Thanks for all the helpful tips.  This forum is great.  Found this thread.
https://forum.w116.org/mechanicals/wiring-hirschmann-universal-antenna-to-79-450sel/msg146878/#msg146878

Multimeter shows red (rt) has 12V, brown is a good ground

But both blue leads are dead.  Radio on, nothing.  Antenna switch full up, nothing.  Should one of the blue leads be hot?

I'm concluding that the short that blew the radio fuse may have fried the antenna circuit in the radio.  Next step is pull the radio and test the antenna lead on the back of the radio, but before doing that, just want to confirm that blue lead should be hot when the radio is on.  Thank you.

UTn_boy

If you have a Becker Mexico or a Grand Prix there is a fuse inside of the actual radio itself.  You remove the top cover of the radio, and them lift the small printed circuit board up. A copper tab holds it in place, and then the board itself will hinge up.  Some had this internal fuse, and some didn't.  Though, I'd take a look anyway.  If you have a Europa or a Europa II Stereo there will be no fuse inside of the radio.   

The blue lead that plugs into the back of the radio (or into the separately mounted amplifier) is the antenna power lead, and should have 12v+ when the radio is switched on. 
1966 250se coupe`,black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3,papyrus white/dark red leather
1975 450se, pine green metallic/green leather
1973 300sel 4.5,silver blue metallic/blue leather
1979 450sel 516 red/bamboo

Taha

If you have 12 volt on amplifier/radio you might have a bad antenna switch. I'd say better to check the antenna itself first. You don't need to remove it for that purpose. Remove the antenna plug cover. Make sure the radio and ignition is off. Make a connection between pins number 1 & 2. If you want the antenna goes all the way up make a short connection between number 5 & 6. Hope it helps.
1978 280S

Rolo

Quote from: UTn_boy on 03 July 2023, 03:45 PMIf you have a Becker Mexico or a Grand Prix there is a fuse inside of the actual radio itself.  You remove the top cover of the radio, and them lift the small printed circuit board up. A copper tab holds it in place, and then the board itself will hinge up.  Some had this internal fuse, and some didn't.  Though, I'd take a look anyway.  If you have a Europa or a Europa II Stereo there will be no fuse inside of the radio.   

The blue lead that plugs into the back of the radio (or into the separately mounted amplifier) is the antenna power lead, and should have 12v+ when the radio is switched on. 

Sir, I believe you have solved the mystery of the location of the second fuse!  Blue not hot when radio is on, so I fried the Kenwood aftermarket radio antenna circuit when I blew the fuse.  Time for a new and better radio probably.  Thank you. 

UTn_boy

Quote from: Rolo on 05 July 2023, 04:57 PM
Quote from: UTn_boy on 03 July 2023, 03:45 PMIf you have a Becker Mexico or a Grand Prix there is a fuse inside of the actual radio itself.  You remove the top cover of the radio, and them lift the small printed circuit board up. A copper tab holds it in place, and then the board itself will hinge up.  Some had this internal fuse, and some didn't.  Though, I'd take a look anyway.  If you have a Europa or a Europa II Stereo there will be no fuse inside of the radio.   

The blue lead that plugs into the back of the radio (or into the separately mounted amplifier) is the antenna power lead, and should have 12v+ when the radio is switched on. 

Sir, I believe you have solved the mystery of the location of the second fuse!  Blue not hot when radio is on, so I fried the Kenwood aftermarket radio antenna circuit when I blew the fuse.  Time for a new and better radio probably.  Thank you. 

After replacing the internal fuse the radio should operate fine. I'd be more worried about the aftermarket antenna.  Try putting an original antenna in, (either electric or manually operated).  The antenna causing the fuse to open will not have ruined your original radio......that's why that fuse is there.....to prevent damage to the radio. 
1966 250se coupe`,black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3,papyrus white/dark red leather
1975 450se, pine green metallic/green leather
1973 300sel 4.5,silver blue metallic/blue leather
1979 450sel 516 red/bamboo

Rolo

I'm sorry.  I wasn't clear.  Hirschmann antenna is OEM.  Radio is aftermarket Kenwood.  The fuse your mention that is inside of a Becker I believe is the second fuse that appears in the FSM wiring diagrams. 

My 6.9 is a daily driver, and I swapped out the OEM Grand Prix for a head unit that has Bluetooth and voice control. 

UTn_boy

Well, with an aftermarket radio there is no telling what may or may not have happened inside.  But with getting 0 volts from the radios power supply to the antenna, I have to assume something is amiss inside of the radio. 
1966 250se coupe`,black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3,papyrus white/dark red leather
1975 450se, pine green metallic/green leather
1973 300sel 4.5,silver blue metallic/blue leather
1979 450sel 516 red/bamboo

Rolo

Happy New Year.  I finally got a chance to dive deeper into the antenna power.  I thought I fried the head unit when the fuse blew when unplugging the Hirschmann with the battery still connected (dumb).  Pulled the radio  and put a tester on the radio's antenna output and it was 12.3 volts.  I followed the radio antenna wiring to the console switch and could find no fuse or disconnected cables.  I tested the blue power wire on the plug in the trunk.  Suddenly it's getting 11 volts.  What? More wire wiggling into the plug, test and no power on the blue wire.  As a last resort, I sprayed De Ox It into the switch.  Test the blue wire and now 12.3 volts.  Dirty contacts in the switch.  Problem solved.

A new problem.  I can't get the new antenna from Mercedessource to feed into the Hirschmann.  I got it in before.  I pulled the back of the Hirschmann, held back the idler wheel and fed the antenna tail up into the housing, but it's hitting something.  Both old and new antenna mast tails show no signs of being broken off.

What is blocking the tail from feeding up there?  Thanks

rumb

I find replacement masts can use a little bevel cut on the end so it isn't so blunt and feeds in easier.
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,
'16 AMG GTS
'21 E450 Cabrio

Rolo

The bevel cut did the trick.  5 seconds with a Dremel and it went right in.  Ken says you have to cut down the masts you get from him so that they retract flush.  He needs to tell customer to do the bevel cut too.