The Dreaded Switching Jack Problem

[guitician]

I guess people just like to clean contacts then, or have their techs do it. So, much for progress.

[52 Bill]

I've seen gold plated plugs, both 1/4" and xlr, not really worth the cost unless you're in the medical industry.

Yorkville sound specs gold plated contacts on most of their break jacks, but only on the contacts that are important. I don't think that I've seen that in any other product.

[Enzo]

Gold plated contacts are fine, as far as they go. They won;t tarnish, and offer low resistance. But that assumes all contact problems involve the metal condition. Gold will do nothing about dirt and film in the jacks. Certainly in clubs, the smoke gets so heavy that cigarette tar and nicotine condense on the surfaces and contaminate them. You can smell a club amp a milke away. Gold won't help.

[guitician]

I would think the spring tension of the gold contact would push through a film, and all it would take is a few molecules touching to get good conduction.

[gtrmann]

This is a real common problem down here in Florida. High humidity and non use of the jacks cause this here. The amp either goes up and down in volume, or cuts out completely... Cleaning the jack is the short term fix, replacing the jack will get you longer. Most guitar players and bassists don't know the jacks are there or ever know their use...

[Joe L]

Same thing here in Louisiana. Lots of humidity and occasional massive hurricanes.

For 35 years, I have used nothing but a strip of plain paper to clean contacts. Just pull it between the contacts with a little added pressure until it comes out clean and you are done. It is a gentle abrasive and won't remove plating.

[Jazz P Bass]

The Dreaded Switching Jack Problem

Here is a new post of the file.

[dbossman]

Hello All,

New to the forum. I am unable to view the pdf file which I assume has more detail in regards to a problematic switching jack. I have a Peavey Bravo 112 that the foot switch doesn't function. I have two other Peavey foot switches and they don't work either. I just bought the amp on CL and it worked intermittently when I first got it, than nothing. If I uplug the foot switch, I can switch the channels from the panel switch fine. What I have been able to determine from the thread is it appears to be oxidization of the jack. I am out of cleaning solution so am curious if this may be a possible issue. I haven't worked on compontent level electronics in over 20 years and am rusty (or oxidized ) and am not sure where the test points are to isolate the problem. Any ideas? I love the amp but really would like to be able to switch from clean to overdrive channel with foot switch.

Thanks,

dbossman

[Jazz P Bass]

I reposted the pdf directly above your post (the site has issues with archived files.)
http://music-electronics-forum.com/a...ck-problem.pdf
As to the Bravo footswitch problem, if the front panel switch works than the circuit is sound.
The jack or the front panel simply 'grounds out' the relay.
Plus the jack has a normally closed contact to allow the front panel switch to function when there is not a foot switch inserted.
Which must be functioning or the front panel would not work.
So that leaves the footswitch itself.
It is a simple 1/4" plug . Tip & Ring.
Tip to Ring should connect or not connect.
That can be checked with an ohm meter.

[Aloha_Mark]

More often than not, these jacks develop problems on guitars as opposed to amps. One guy sent me a vintage guitar with severe corrosion at the tip of the jack and when I connected the instrument to the amp, it sounded like an attack of the humming-spitting-crackling bees. It was loud and ugly. Rather than using DeOxit, I just wired a new gold plated jack into the guitar. Screw vintage correctness. To be politically correct, I use Monster guitar cables, which have gold-plated plugs.

[imaradiostar]

I don't recall if it's Monster Cable brand or not but the gold plated jacks often are too snug and the plug and jack can become permanently attached, leading to replacement of both! It seems some brands don't account for the thickness of the plating on the plugs and jacks.

JT

[guitician]

I don't recall if it's Monster Cable brand or not but the gold plated jacks often are too snug and the plug and jack can become permanently attached, leading to replacement of both! It seems some brands don't account for the thickness of the plating on the plugs and jacks.

JT

It's more likely that the metals became fused due to corrosion from the porous plating. Solid silver would work much better than any plating. And it could just be a thin tube over some tough plastic, no need to use a lot of silver.

[nevetslab]

At least on the Tektronix scopes, you're dealing with wiping contacts, where you can exercise the switch repeatidly. Or, on any piece of gear where switches can be exercised (50-100 times often) to wipe thru the long term buildup of oxidation. On Jack 'normals', though I too have had to resort to coating some abrasive paper with DeOxit, and repeated wiping between the normal contacts. When you can't get at the contacts, it's a bloody problem. Console patch bays in studios are just full of normals. Servicing those, you hope and pray the installion team left you enough service loop in the wiring. Repeated 'patching' of the patch cord into those only helps marginally, as there's NO WIPING ACTION on normals. it's a LIFTING ACTION.

I run into the Insert Jack problem often enough servicing backline gear. At least on most of those jacks, if using Cliff or similar exposed contacts, you can slip in wetted abrasive paper to clean the contacts. When all else fails, insert a short patch cable into the Send/Rtn jacks to restore order. In the studios, dealing with viintage consoles, it's not uncommon to see a lot of patch cords completing the path.

The source of the trouble is oxidation build-up over time. Been dealing with that problem for decades. Old Equipment-itis. Switches that don't ever get used, and someone pushes it, and now you've lost signal. Listening to it, it's grungy distortion, though most of the time, repeated exercising of the switch will get the switch to clear its' throat. Same holds true with rotary siwtches. Any mechanical device in the signal path is prone to this slow deterioration. I typically use 50-100Hz sine as a test signal when I'm exercising the switches. Goes from being grungy or no signal to finally sounding like it did when new. Be aware, though, that you may also have found switches that have solder fractures on the PCB. Most are NOT mechanically supported.

Pots, too have the same long term oxidiation problem. Racking the pot back and forth repeatidly will, most of the time, restore order. Contact cleaner helps in this action, but you still have to exercise it. On old pots, where there are no replacements, I often have to disassemble the pot to do thorough cleaning. On some, that also involves copper cleaning compound to restore the metal to bright shiny appearnce. Re-assembly with application of a little red grease helps, to restore the viscosity feel it had when new. Contact cleaners destroy that grease that lubricates the shaft/bushing area of the pot.

I do a considerable amount of vintage gear restoration, including consoles, so it's a tedious & time-consuming process, restoring the mechanical signal path so it doesn't break up & distort in use.

[Enzo]

For CLiff-type jacks, I have used a 1/8" burnisher for decades, it works like a charm.

Mine is a GC9337, made by GC.

FRYS.com | GC Thorsen

There are also wider ones.


Back when I worked on relay systems we used burnishing tools a LOT.

[nevetslab]

I have one of those, come to think of it....need more, as the one I have is out at a friend's keyboard repair facility. They work quite well..thanks for reminding me!