Intermittent Jack Problem - diyAudio
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Old 31st January 2006, 03:45 PM   #1
m1p1 is offline m1p1  United Kingdom
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Default Intermittent Jack Problem

Iím a lapsed bass player and yesterday I dug my 20+ years old Ohm 125 watt amp out of the attic, bought new guitar and speaker leads, connected up to my Carlsboro 18 inch bass bin and powered up the amp. The amp was reluctant to come to life, but after a little fiddling it started to make music. Then it stopped. After a while I eased the guitar lead jack out of the amp and it cam back to life again. Then it stopped again. This happens every couple of minutes and is cured by easing the guitar lead jack into or out of the amp. Has anybody come across this or would anybody know of a likely cause? Thanks.
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Old 31st January 2006, 04:08 PM   #2
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It could just be that the contacts on the socket have tarnished?, try squirting a little WD40 on the jack plug, then push it in and out a few times and rotate it.
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Old 31st January 2006, 06:16 PM   #3
Brion55 is offline Brion55  United States
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What Nigel said is the first thing to try. Most guitar amps have "shorting" type input jacks so that when there isn't a plug inserted the input is shorted to ground to keep it quiet. Sometimes the jack loses its "spring" and the plug doesn't move the tip contact enough to unshort the shorting switch. If all else fails, just replace the jack with a Switchcraft or Neutrik jack. Don't waste your time and money on cheap jacks.

You can get good jacks from: http://www.partsexpress.com/
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Old 1st February 2006, 02:27 AM   #4
Enzo is offline Enzo  United States
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I am suspecting he can find a supplier of jacks in the UK too.
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Old 2nd February 2006, 07:32 PM   #5
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Another problem often found on this type of amplifier is the switch contacts on the FX send and return jack sockets - they oxidise or tarnish over time - especially if not used.

To prove if this is the cause - gingerly insert a plug and gently withdraw it - does the signal intermittently come and go?

Don't use WD40 - this is for creaky hinges and such only!

There might also be a headphone socket on your amp also (why? - nobody EVER uses this!). Again switch contacts get dirty.

If you never use these sockets - bridge the contacts with a soldered wire link. If you do - then replace them with new jack sockets.

RS and Farnell certainly have them available in the UK.
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Old 3rd February 2006, 08:59 AM   #6
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Quote:
Originally posted by John Audio
[B]
Don't use WD40 - this is for creaky hinges and such only!
And it's also an EXCELLENT switch and contact cleaner, I've been using it professionally (as do all our engineers) for something like 25 years - it works far better than specific 'switch cleaner' products - and we've never seen a problem with it.

What you mustn't EVER do though is squirt it inside a VCR or cassette recorder - you wouldn't beleave how many of these I've scrapped after customers squirted WD40 through the cassette slot?.
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Old 5th February 2006, 12:08 AM   #7
testlab is offline testlab  United States
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I have to disagree with Mr. Goodwin about the WD-40. Caig Deoxit is much better and safer for electronics.
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Old 13th February 2006, 04:10 PM   #8
Brion55 is offline Brion55  United States
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I would agree that Caig products are the best for electronics, but they aren't usually available locally.
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