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Sennheiser HD429 Earphones. Cable broken.

Michael Studio1

Jan 5, 2018
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These are over-the-ear headphones - but I'm on holiday and just tripped over the cable and yanked it out of the T/R/S plug. Broke all connections at the solder joint so no clue which went where. Very thin three-core cable with fabric/stranded colours of: Red, Blue, Orange. Any ideas out there? (I just happen to have an old soldering iron here and some cored solder!) Otherwise the Sun is shining, the North Sea is blue and no-one is on the beautiful sandy beach. Howzatt! Studio1.
 

Alec_t

Jul 7, 2015
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Do you have an Ohm-meter with you on hol? If so, measuring resistance between the wires should give a clue as to function. With that sort of wire I've found putting the ends briefly in a small flame was necessary to burn off an insulating layer which prevented soldering.
 

Michael Studio1

Jan 5, 2018
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Thanks Alec - indeed I do - a very small Altap Digital Multimeter DM830. I must confess that approach simply had not occurred to me! As to burning off the loose very fine outer layer - Brill! - that too hadn't crossed my mind! So what would I expect to find - and almost 'short' indicates the coil and the remaining core would be GND? Give it a whirl! However, finding I have no mini vice to hold the 1/8" T.R.S. Jack while soldering or even a bench - or a decent soldering iron I have decided not to even try! I shall leave it until I get back to the Studio&Workshop next Month where I shall implement your ideas. I am not bereft either for I do have a pair of Sony WH-1000X M3 Michael. Studio1.
 

Alec_t

Jul 7, 2015
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So what would I expect to find
I repaired a headphone set (not the brand you have) with a similar broken cable problem. I found about 30Ω from wire A to wire B, the same from wire C to wire B, so concluded that B was a common ground and that A and B were the Left and Right channels (though which was L or R remained a mystery). Your mileage may vary.
 

Martaine2005

May 12, 2015
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Can you not open ‘1’ ear piece? That would then be definitive. Screws are usually under the outer foam.
I would also cut a few inches (50mm) off the jack end as the wire naturally weakens over time in that area.


Martin
 

Michael Studio1

Jan 5, 2018
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I repaired a headphone set (not the brand you have) with a similar broken cable problem. I found about 30Ω from wire A to wire B, the same from wire C to wire B, so concluded that B was a common ground and that A and B were the Left and Right channels (though which was L or R remained a mystery). Your mileage may vary.
Thank you Alec. That is a useful suggestion. Noted for Workshop use! Michael
 

Michael Studio1

Jan 5, 2018
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Can you not open ‘1’ ear piece? That would then be definitive. Screws are usually under the outer foam.
I would also cut a few inches (50mm) off the jack end as the wire naturally weakens over time in that area.


Martin
Thank you Martin. I have removed the Left ear-piece and am pondering the cause for the underlying 'insert' being impossible to 'spring' out. Maybe there's a screw in there somewhere as it can be prised up but springs back into place as soon as the pen-knife is removed. I am a tad reluctant to 'force' anything! The ear-pieces are intended for replacements I think. But the underlying 'insert' with its corrugated smoky-clear 'speaker' membrane react as above to removal. There is a thin black, ovoid foam stuck to the insert revealing the circular 'speaker' membrane beneath. I think it would be best to leave well alone and make those measurements with the multimeter. The colour-coding of the 3 core may be relevant to purpose: Red, Blue, Copper. Suggesting: Red = Right. Blue = Left, Copper = Common. The multimeter I have here shews inconclusive and variable readings in the Ohms section. Again this will all have to bide its time until my return to the Studio & Workshop with its better equipment - and small vices to hold things for soldering. That will be at the end of the Month. I will be applying your collective advices. Michael-by-the-North-Sea
 

Martaine2005

May 12, 2015
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Hi Michael, my old RS-120 wireless headphones are very similar and so are the HD-428 wired headphones. I once replaced the ear cover foam and remember it being difficult. I did manage to do it somehow. But a little internet search revealed this YouTube video. It is pretty much brute force. Then the screws will be visible. However, plastic does go brittle so a little care should be taken.
Jump to 1:25 in the video as it’s a terrible video.


Martin
 

Michael Studio1

Jan 5, 2018
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I suddenly thought of using a 'button' cell to test these headphones. And I was right! I put the headphones on for this test! The 'copper' coloured lead is the Common and the red is Right and the Blue is Left.I let my ears take the brunt of this measuring! To remove the fine covering of a small length (1/4") of each core I held each one with pair of pliers and exposed the 1/4" to a gas fire-lighter. That worked too and also tinned those tails! Martin - the Transistor/Diode Atlas device is in the post to you with some blue sky, sunshine and North Sea wind - for good measure. Michael
 

Martaine2005

May 12, 2015
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Great on both counts.
Everything is getting smaller and harder to work with. Even with a microscope and small tipped iron or hot air. Tweezers take some getting used to too!.


Martin
 

Michael Studio1

Jan 5, 2018
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The one piece of equipment we have just installed in the Workshop is a real boon!
A Vacuum Pumped Soldering-iron. This makes those tedious jobs of removing a
multi-contact device so much simpler. It was a terrific asset when removing one
leg of the sixteen Diodes in the PSU of the Sanyo VTC5000 Beta player/recorder.
Michael.
 

Martaine2005

May 12, 2015
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Yes, they sure are good. Be mindful when using it though as They can pull pads off quite easily. Don’t ask me how I know!.


Martin
 

Michael Studio1

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Well, of course, I found it unnecessary to take those pads off atall since getting into the connections on the 'drivers' (or whatever they're called - phones?) was no longer required following the 'Button Battery Test' and the thin (very thin) three cored cable is still OK. So I sha'n't ask! But I shall assume!
Michael.
 

Martaine2005

May 12, 2015
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No, no. I meant the solder vacuum pump easily pulls off solder pads on the PCB.


Martin
 

Michael Studio1

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A-Ha! Now that's a different story! I agree one needs to ensure there are no solder pads to be sucked off the PCB before applying this splendid suction-pump de-soldering tool! Q: What are these pads intended for anyway? and: why would they be on the 'trace' side of the PCB? (the only side one would apply the de-soldering tool) Probably a 'silly question! - but tell just the same! Michael.
 

Martaine2005

May 12, 2015
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A solder pad is where the electronic component gets soldered to. It’s the copper ring in through hole boards and little circles or squares on surface mount boards.
Here’s a pic of a through hole board with copper rings. That’s what you are sucking/vacuuming off the board when desoldering.
upload_2022-8-6_14-23-11.jpeg

Martin
 

Michael Studio1

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Thank you Martin. This is extremely interesting and useful information! Please advise on one aspect: Are these 'rings' not a physical/electrical part of each 'trace' to ensure electrical continuity? If so I imagine a Very Strong glue is used to stick both 'trace', tabs and 'pads' to the PCB. I have no idea of the subject of engineering factors concerned in the building of a PCB. Michael.
 

Martaine2005

May 12, 2015
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Are these 'rings' not a physical/electrical part of each 'trace'
Yes they are but the suction can rip them off. Therefore breaking the trace.
The trace can also ‘lift’ requiring either gluing back down or cutting and inserting a ‘jumper’ wire.
Also, the pads are probably the weakest link as no solder mask is covering it. (Green coating on above board).

Martin
 

Michael Studio1

Jan 5, 2018
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Yes they are but the suction can rip them off. Therefore breaking the trace.
The trace can also ‘lift’ requiring either gluing back down or cutting and inserting a ‘jumper’ wire.
Also, the pads are probably the weakest link as no solder mask is covering it. (Green coating on above board).

Martin
So there is a repair - a jumper is the best. Worth bearing in mind. Michael
 

Michael Studio1

Jan 5, 2018
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Which glue is best for gluing down PCB traces? CA glue? (CyanoAcrylate) or is that 'too hard' a glue? Suggestions please! Not
that I currently have this problem - but fore-warned is good to know.
Michael.
 
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