Input jack now only works if I input the plug half way in?

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weelie
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Joined: Wed Apr 07, 2010 10:23 am

Input jack now only works if I input the plug half way in?

Post by weelie » Thu Feb 09, 2012 8:43 pm

Hi,

I was playing my electric (uke) today and suddenly slowly lost the sound. Then I was trying to get it back, I realized I can get sound if the plug is only halfway in to the input jack. But it doesn't stay in that way, so...

I took the jack out, to see what it looks like... it has two lines (soldered to terminals) going in and inside the shaft of it there are two "hook"-like bent-in metal plates. It appears that I can get a sound connecting to either of the lines coming in, and when the plug is halfway in, it only touches one of the hooked metal plates. (Also it seems that the tip of the guitar cord plug is the active part, and the shaft is not.)

Help! What gives? How does this thing really work? How do I fix it? I could bend the metal plates either way, I tried bending them tighter, didn't work, tried loosening them didn't work.

Thanks in advance!

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losaavedra
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Re: Input jack now only works if I input the plug half way i

Post by losaavedra » Fri Feb 10, 2012 10:30 am

Jack plug to socket connections are pretty simple in electrical terms, just relying on pressure contact between the plug (via tip and barrel body) and the socket's contact 'springyness'. Check that there is signal and ground continuity on the connecting cable itself as its more likely a problem there than in the socket. Best way is to try a different connecting cable and see if the problem goes away. Problems in the plugs and lead are usually a result of one or other of the two connections coming undone due to the strain imposed by the the weight of wire between the amp and instrument end of things.

The socket on the instrument, into which the plug goes, is usually a very simple springy arrangement for the signal side that's supposed to make contact with the plug tip when its inserted, while the sleeve through which the plug is inserted provides the ground contact on the plug's barrel. For this arrangement to work as a means of making the electrical connections BOTH must be making proper contact. If only one contact is present, and its the signal without ground ... then that will usually produce a hum, while if its ground without signal then you'll get nothing at all.

Basically its a job of elimination. Try a different cable first. If still no-go then start to look at the sockets. Sounds like you're already trying the instrument socket. If its the amp socket at the other end then try to prove it by a test using a different amp! Problems with amp input sockets are rather more complicated to sort out, probably requiring a tech, so eliminate the easy things first!!
Mike
"I feel more like I do now than when I first came on" (Ronnie Scott, Maidstone)

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weelie
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Re: Input jack now only works if I input the plug half way i

Post by weelie » Fri Feb 10, 2012 2:07 pm

Thanks!

Yeah, I did check with different cable and amp. Same result.

OK, if I connect with either RED of WHITE, I get signal and hum. Like you said.

If I insert the cord plug in, I get silence. If I got hum, I would understand that one of the connections is not made. But why silence? Should the RED go to tip and the WHITE to shaft, and now both are connecting to tip? Would that be a possible cause?

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MikeJackal
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Re: Input jack now only works if I input the plug half way i

Post by MikeJackal » Fri Feb 10, 2012 2:15 pm

Think of it as a normal plug, the tip is your live and the sleeve is your earth, on most guitars the tip connects to your selector switch but from the picture it looks like you don't have one. The tip will probably connect to the middle lug on your volume pot in that case, the earth should be soldered to somewhere like the back of a pot. Make sure you have one wire doing each of these jobs.
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