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Anti-Guru
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:( I've included specific questions at the bottom of this post that I would love to hear thoughts / opinions / experiences about...


... I would also ask that the brilliant minds (and others) kinda follow along with my overly wordy diagnosis, just to see if mythoughts on repair seems insane. This is the first time I've encountered anything like this, so I'm just checkin'

BIKE:1988 [email protected] 95k miles; mine, damn it!

SYMPTOM: Both rider and passenger report no audio from same channel of headset.

DIAGNOSIS: Assumed loose connector, harness failure, faulty radio; the only non OEM part in this loop is the radio and a passenger Mic-Cut switch (an inline plug-n-play that opens the Mic input for the passenger's pigtail).One set is J&M; the other is Ed Set.

Infield diagnosis precluded obviously loose connection at radio.

In the shop, I verified the 3-wires common the front and rear headsetpigtails for continuityto the radio connector (bike harness; pin-to-pin; full length), and mutual isolation in these wires. I also verified each of the two pigtails and the Mic-Cut for continuity and isolation separately from the harness. Plugging the pigtails back in, I re-verified isolation and continuity to pigtail to pigtail.

Next was a radio swap; dang nice to have spares. SAME issue, no change in symptoms. :X

I ran the radio on a "noise only" AM station and was able to verifyAC signal (assume it's audio at low levels) on both of the headset output wires (at the radio and again at the headset plugs. Output on the "failed" channel measured slightly higher.

Suspecting the headset, I measured the DC resistance of the speaker elements in the headset I was using for test. OPEN CIRCUIT on the bad channel.

Could I have two headsets with the same failure? Yep - got the other helmet and found the speaker element similarly open.

I returned to the bike to see if I had some DC imposed on the "audio" output for either channel. No DC was present even at extreme output levels - measured with good music, CB and intercom allowing for manual and automatic mute (thinking that MUTE may go DC) --- No DC found.

CONCLUSION: I have two helmets BOTH with the same channel speaker blown.

VERIFICATION: Grabbed a spare headset (loose, not installed). Verified good audio output from both speakers.

REPAIR: Replace the damaged speaker elements (and/or complete headset assys)

:praying:QUESTIONS:

1) Does this even seem reasonable? (am I insane?)

2) Has anyone seen anything remotely like this?

3) I've not been able to isolate a causal event, how am I gonna keep this from happening again? (a 47µfd capacitor inline with the outputs wouldblock DC to the 70-ohm headset speakers without significant low-freq loss)

4) Any ideas on what could cause one channel of both headsets to open? I'm assuming this is electrical - very low hours on the passenger's set - rider's set is in constant use and worked reliably until the issue was noted (seemingly precipitated by the passenger's set being plugged in)



Please, and Thanks to all ... I'm interested to hear your thoughts.
 

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It's unlikely both headsets developed the same fault at the same time. You ruled out the radio, the only think left is a harness problem.
 

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Reddy wrote:
It's unlikely both headsets developed the same fault at the same time. You ruled out the radio, the only think left is a harness problem.
But not impossible...

I think installing another headset and finding both channels working proves that it is the headsets at fault. However, there may be something in the radio/harness that is causing the same speaker in each headset to fail.
 

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Monkey with a Football
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Both of them going is either a coincidence or a DC component is silently cooking the voice coils.

Easy enough to read with a meter. Just put it on DC, turn on the amp and leave the volume down.

Ideally I would also test it with an O-scope and add a sine wave for a signal so you could detect DC offset when the amp was driving the coils.
 

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Rudy wrote:
Both of them going is either a coincidence or a DC component is silently cooking the voice coils.

Easy enough to read with a meter. Just put it on DC, turn on the amp and leave the volume down.

Ideally I would also test it with an O-scope and add a sine wave for a signal so you could detect DC offset when the amp was driving the coils.


+1

May have a dc offset creaping up when you key the cb or when it chimes in over the music.



Which side is blown? Is it closer to the cb antenae?
 

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Wow, what a coincidence, Stan !! Just Sunday, we had pulled into S. Umpqua Falls, and everything was good. 1.5 hrs later we load up, hit starter, and Pat says "No left sound". That's when I noticed I had no "right sound". Assumed it was a channel in wiring, or radio. Reset the radio, and that didn't do anything. :?

Monday, I started checking the outputs. OK The RH transducer was dead (open) on my helmet, and a wire broke on her volume control. We both swear that the system was ok up to that point.
 

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I'd not tested with the CB in x-mit -- I'll have to give that a go ...

The look for DC was done with the old Textronix 465 0-scope here in the shop, but I'll repeat with the CB in X-mit. (interesting thought; thanks!)

I had some aditional time to re-think the time of failure to ty to pinpoint a cause. The rider's set was working correctly when last used less than an hour before adding the pillion rider. The pillion set was working at last use (about a week prior). The "failure" was noticed at the firs comm-check after the pillion plugged into the intercom system. This has me thinking about connector scrubbing at the 5-pin DIN... I'll take a quick look to see if there's some serious DC levels that exist on pins/plugs that may have scrubbed while the pillion was connecting.

It looks like this all happened within a few seconds when the pillion connected the coiled-cord to the helmet connector (or at least that's when the rider's set was affected, it's possible that the pillion failed at the last disconnect - no ability to isolate timeline there)

I brought out one of the "spare" pillion hats (old Chatterbox) for continued testing and still didn't see any DC or notible low-frequency stuff that could get close to cooking the little speakers...

My working theory is DC, source unknown so far. Since the speaker elements are in parallel, the first one to fail would have reduced the load on the DC source, which could help the other set to fail.

I'll try to retest with 2-sets of speakers connected (incase there is an issue with the total parallel load)...

other thoughts?
 

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Oregonwinger wrote:
Wow, what a coincidence, Stan !! Just Sunday, we had pulled into S. Umpqua Falls, and everything was good. 1.5 hrs later we load up, hit starter, and Pat says "No left sound". That's when I noticed I had no "right sound". Assumed it was a channel in wiring, or radio. Reset the radio, and that didn't do anything. :?

Monday, I started checking the outputs. OK The RH transducer was dead (open) on my helmet, and a wire broke on her volume control. We both swear that the system was ok up to that point.
:gunhead:Solar flares ? Damn it! Can't say much for Sunday, but Saturday had some events :) http://www.swpc.noaa.gov/ftpmenu/indices/events.html
 

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Satan,

How did you check the headphones? Did you go from pin to pin on the connector or directly across the speaker?
 

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I rang-em-out from the conenctor first (actually used the pig-tail from the bike as it's easy to probe the mitsu-plug there...)

Then verified by piercing the harness right at the installed speakers themselves. I had hoped that this was all loose connectors or faulty cords ...
 

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Im going with either 5 pin DIN pin scrub and / or an intermittant short in the coiled cable were it connects to the DIN plug , Try checking for shorts while " whipping " the coiled cord about. If you can get into the back of the DIN plug easily , look for fraying of those tiny multi. strand wires caused by continual " whipping " of the cable through normal usage. Have seen this with CB mikes etc.
 

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Satan,

I think I would replace the speaker (if it's not all that expensive) and enjoy the wing. You can loose a lot of sleep and ride time if it turns out to be nothing. If you do have a DC voltageon that ch thenthe audio output ckt is in need of repair. Once again, "stuff" happens and sometimesan answer is never found. Good luck.
 

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Thanks all, and a bit of follow-up.

I swapped both sets and cords with "spares" here, and we'll see what happens now :p

I wasn't able to find anything in any of the connectors that could have scrubbed, so this is just gonna be a "hey your 20-year old headset had ONE speaker fail and the 10-year old set failed from whatever happened.

Heading to the Colorado District Rally this weekend and don't expect any trouble for 10 or more years from these things :p

I'd just not heard of a "dual failure" like this...
 
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