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FA-011 Repair -- Right & Left shorting?
Jul 8, 2016 at 4:54 AM Thread Starter Post #1 of 14
Abasees

Abasees

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Hi guys, A while ago my fischer audio FA-011's broke, the wiring inside had become disconnected. I went about fixing it, and have done so (as well as putting a 3.5mm stereo socket into them so I can use a removable cable). This has all worked well, but when I was testing the audio, I noticed that playing audio in either the left or right channel only still comes out of the other channel as well when it shouldn't be (I tested with: https://www.youtube.com/watch?v=hTvJoYnpeRQ).

 

I was wondering what was causing this, as I can't see any shorting going on visually. Here are a couple of photos:

 



 
 

 

 



 
Jul 8, 2016 at 7:21 AM Post #2 of 14
It's kind of hard to see what is going on in the wiring but it looks OK.  When you had them apart did you measure the resistance of the drivers. If so then you should be able to tell if they are connected properly by measuring the resistance from the tip and ring of the cable end plug to common. So if they are in parallel or series due to a wiring error the resistance should reflect that. Also, if they are in parallel the tip and ring would measure close to 0 ohms. Perhaps the jack is a shorting type? To verify your findings with the signal source you should be able to use an ohm meter to test them . You should hear a click in the appropriate side when checking the resistance. 
 
Jul 8, 2016 at 8:27 AM Post #3 of 14
jdbrian said:
  When you had them apart did you measure the resistance of the drivers. If so then you should be able to tell if they are connected properly by measuring the resistance from the tip and ring of the cable end plug to common. 
Click to expand...

 
Hey I didn't measure the resistance of the drivers unfortunately. What do you suggest I do with the ohm meter, I'm just a bit confused sorry.
 
Jul 9, 2016 at 12:57 AM Post #4 of 14
In testing the resistance i did hear the discharge noise at times come out of the speaker.

 

on 3.5mm socket:

tip to ring ~ 320 ohms

tip to sleeve ~160 ohms

ring to sleeve ~ 160 ohms

 

 To make things easier, I've labelled the solder points on the left speaker 1 - 4 which you can see here:

 



 
 

and here are the results --

tip -> 1 160 ohms

tip -> 2 0 ohms effectively

tip -> 3 130 ohms

tip -> 4 130 ohms

ring -> 1 160 ohms

ring -> 2 320 ohms

ring -> 3 189 ohms

ring -> 4 189 ohms

sleeve -> 1 0 ohms effectively

sleeve -> 2 160 ohms

sleeve -> 3 30 ohms

sleeve -> 4 30 ohms

1 -> 2 160 ohms

1 -> 3 30 ohms

1 -> 4 30 ohms

2 -> 3 130 ohms

2 -> 4 130 ohms

3 -> 4 0 ohms effectively
 
Jul 9, 2016 at 7:26 AM Post #5 of 14
Great job on posting all those resistances and labelling the diagram! It certainly seems to be wired properly based on the resistances you have measured. Next, I would attach a cable to the socket and measure the tip to ring, ring to sleeve and tip to sleeve resistances. This will check the socket to make sure it is making all the connections as well as the integrity of the cable. 
 
Jul 9, 2016 at 7:41 AM Post #6 of 14
Okay will do and post back results, thanks for being so helpful! Should this be whilst its plugged into the computer? or just with a cable plugged in only at the socket end (and not back into computer)
 
Jul 9, 2016 at 8:00 AM Post #8 of 14

No problem. With the cable plugged into the socket end and using the ohm meter on the end that would normally plug into the computer. I just recently repaired my oldest  headphones, a set of Audio Technica ATH 5 that I bought in about 1975.  First HPs I bought and they have been lying around broken for about 25years. Broken wire right where it went into the ear cup.  They work fine now but are a bit dull sounding compared to most newer stuff. 
 
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