Strange problem with jack plugs

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Strange problem with jack plugs

This topic has 10 replies, 6 voices, and was last updated 1 August 2022 at 18:14 by Ian Parkin.

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31 July 2022 at 12:16 #607982
Ian Parkin
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@ianparkin39383
A customer let me have 2 stapling machines that the operators had damaged all the wiring that triggers the action

it was a 3.5mm jack socket with a switch in it to short the live to earth when the plug isn’t in it.

the 2 wires from the 3.5mm plug go to a foot switch with a nc v3 micro switch

when the plug isn’t in the machine theres a switch that operated by the action of putting paper in whilst in flat mode. The foot switch is used when saddle stitching.

so i thought I’d upgrade the sockets and plugs to 1/4 versions..however when i did this the machine wont work.

if i have the 2 wires coming out of the machine and hold them in my hands with me holding the bare conductors and disconnect them the machine wont trigger if i hold by the insulation it triggers when broken from its nc state.

so thats resistance from my skin?

but why wont these sockets and plugs work?

I know thats a stereo socket and a mono wire….the socket isn’t damp.

the 3.5mm in the picture is what was fitted.

any ideas?
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31 July 2022 at 12:16 #32273
Ian Parkin
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@ianparkin39383
31 July 2022 at 12:24 #607984
Ian Parkin
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@ianparkin39383
Just another point if i have the machine switched on ready to go with no plug in the socket and remove one wire from the socket the machine triggers..place the wire back on and off again and it triggers …so its just like the socket is shorted..but my meters show no short.
31 July 2022 at 12:28 #607985
peak4
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@peak4
At first glance, does the ¼" socket have an NC switch twixt tip and sleeve?

Bill
31 July 2022 at 12:39 #607986
Ian Parkin
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@ianparkin39383
Bill

it has 3 nc switches one for each pole
31 July 2022 at 12:57 #607988
Andy_G
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@andy_g
Posted by Ian Parkin on 31/07/2022 12:39:37:

it has 3 nc switches one for each pole

Have you wired the switches to short tip to sleeve when the plug is removed?

This is usually intrinsic to the design of 3.5mm sockets, but needs to be wired in for the 1/4" socket in your picture – There needs to be a wire between the sleeve contact and the *switched* contact on the tip for it to function like the 3.5mm one.
31 July 2022 at 13:02 #607989
Keith Petley
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@keithpetley53472
I recall having trouble in the past using mono plugs in stereo sockets. The tip of the mono plugs was more generous in length than those on the stereo plugs and the centre contact on the stereo socket landed across the insulator ring and shorted the plug.

Try placing an insulated wedge into the centre switch contacts to lift it clear of the plug and use the outer pair of contacts.

Keith
31 July 2022 at 13:04 #607990
Ian Parkin
Participant
@ianparkin39383
At the moment theres only 2 wires one to the sleeve and one to the tip and if i put a plug in good continuity to the wires and no measurable short.

the electronics in the stitcher head must be very sensitive to the resistance between poles on this brand of sockets
1 August 2022 at 11:37 #608064
SillyOldDuffer
Moderator
@sillyoldduffer
Posted by Ian Parkin on 31/07/2022 13:04:21:

At the moment theres only 2 wires one to the sleeve and one to the tip and if i put a plug in good continuity to the wires and no measurable short.

the electronics in the stitcher head must be very sensitive to the resistance between poles on this brand of sockets

Chief suspect is that stereo socket. I agree with Keith – mono plugs often don't fit properly into stereo sockets. The mismatch is best avoided because it's uncertain what makes contact with what and when. Using a stereo socket also introduces the wiring uncertainty mentioned by Andy.

The stapler's electronics are likely to be sensitive which would explain some of the odd behaviour. Almost certainly the stapler contains a high-gain amplifier arranged to debounce a correctly wired switch. The debounce circuit is probably built from high-impedance (voltage driven) semi-conductors that could respond to mains hum or radio frequency interference if the circuit isn't terminated properly. Testing anything electronic by manually manipulating dangling wires is likely to mislead. Electronics are orders of magnitude faster and far more sensitive than power electrics so the sort of temporary lash-up that's good enough for deaf as a post electricity, is likely to introduce a multitude of side-effects that electronics will react to.

Fitting a normally closed mono socket might well be enough to restore order.

Dave
1 August 2022 at 14:32 #608088
Martin Connelly
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@martinconnelly55370
You have not answered Andy_g's question. Have you put a link wire between the two switched terminals on the 1/4" socket? If you don't do this then when the plug is out of the socket the two wires going to the socket do not make a closed circuit.

Martin C
1 August 2022 at 18:14 #608104
Ian Parkin
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@ianparkin39383
Before using the switched function on the sockets i was trying to get it to work with just 2 wires one to tip and one to sleeve..nothing I could do made any difference.

bought another brand of sockets and problem went away..so i now have a bag of 10 3 pole 1/4 sockets spare..

Edited By Ian Parkin on 01/08/2022 18:14:55
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