Author Topic: 3.5mm headphone socket fault cause  (Read 1177 times)

3.5mm headphone socket fault cause
« on: 19 September, 2018, 01:47:45 pm »
My HiFi system has stopped working. As far as I can tell the 3.5mm headphone socket is mistakenly thinking that a jack as been inserted therefore cutting sound to the speakers.

Therefore my question to the panel is how does the socket know a jack has been inserted? Does it rely on continuity between the channel and ground or is there a separate contact that is closed when the jack is inserted that tells the system to cut the speakers?

TIA

Kim

  • Timelord
    • Fediverse
Re: 3.5mm headphone socket fault cause
« Reply #1 on: 19 September, 2018, 01:54:23 pm »
Both schemes are used (simple audio kit tends to use switch contacts, computers and smartphones tend to sense electrically).  You may gain a clue as to which by examining the outside of the jack and how many pins it has.  Which you'll want to do anyway to check for the dry solder joint that's often the cause of problems with such things.

Re: 3.5mm headphone socket fault cause
« Reply #2 on: 19 September, 2018, 03:06:31 pm »
So if there are three pins then it is electrically as they would be left, right and ground. However if there are more pins (potentially 5) then this would imply the socket has the built in switch that closes when the Jack is inserted.

Time to get a screw driver out and start counting tracks in the PCB.  :-\

How would I diagnose a dry solder joint?



ps the equipment is now ~15 years old and served well for 14 years before developing an intermittent fault for realising the jack was not there and then finally failed completely.

Kim

  • Timelord
    • Fediverse
Re: 3.5mm headphone socket fault cause
« Reply #3 on: 19 September, 2018, 05:26:34 pm »
How would I diagnose a dry solder joint?

Sometimes you can see that the solder is no longer attaching the pin to the board, and that there's visible movement somewhere.  Sometimes it just looks a bit dull and grey, rather than shiny, or that it's formed a blob rather than flowing across the surfaces its meant to be joining, although lead-free solder always looks a bit crap.  If in doubt, it doesn't usually hurt to re-flow the joint with a bit of fresh solder.

On a bad day, the solder joint is fine, but the copper track breaks free from the board.  Fixing that sort of thing tends to involve bodge-wire between the pin of the component and somewhere else on the track.

There are countless soldering videos on Youtube, so that's a good place to look for examples of this sort of thing.

Valiant

  • aka Sam
    • Radiance Audio
Re: 3.5mm headphone socket fault cause
« Reply #4 on: 29 September, 2018, 01:24:12 am »
Spray some servisol contact cleaner and plug the jack in and out multiple times. Usually does the job for me, especially on mixers.
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