The horror of ckt. board mounted jacks

[ron45]

I've always been careful/mindufl of the s**t printed ckt boards are. And still my Vox tonelab EX came up with a intermitent connection is the mini stereo aux input jack. I hate the idea of paying for corporate greed so I'd like to know is silicone calking is electrically inert or a non nonconductor. If not what is. I'm thinking it might be worth the time so open it up if I could stabilize the connections in the signal passing mode again. I'd know this w/a male mini plug and a multimeter. What I don't know is other than an open what might I see in terms of a usefull ohm reading. Hard to pin down I know but just something ball park should do the trick.

If you have a better idea of how to be sure it's in the right position to pass the signal please feel to correct any of my greed driven notions.

Thanks for your time also

Ron

[The Dude]

First, check the solder on the jack pins. Much of the time they just crack loose and a little resoldering will do the trick.

[ron45]

Yes! good thinking. I guess it's not your first rodeo. Alas, I have tried several different mini patch cables but it wouldn't hurt to check anyway since it's so easy.

Many thanks.

ron

[Enzo]

And a jack failure may have nothing at all to do with the fact it is mounted on the board.

I am not sure what the silicone question is about in this context, but silicone sealer is sometimes applied to parts that stick up or have mass or are subject to flexing. This helps prevent solder cracks. yes, silicone is an insulator. Other amps will use hot melt glue instead of silicone for the same purpose.

[Mick Bailey]

Mostly the internal switching contacts just oxidize. It happens with hard-wired panel sockets in FX loops as well, so not just on PCB amps. In the main they fail because they don't get used. There's a minimal self-wiping action that keeps sockets 'clean' that are in use. When they're unused, air and moisture causes eventual failure.

When you take a reading across contacts you should see close to zero ohms. Anything more and the socket could be problematic.

Before 'fixing' a problem, first establish the cause. If the socket has failed due to lack of use and the solder joints are good, then applying silicone doesn't fix anything. In fact, the acetic acid liberated during curing can worsen things, unless it's an acid-free curing type.

Sometimes a squirt of contact cleaner and excercising the socket by plugging in an out a dozen times will fix the problem.

[Enzo]

My rule of thumb on jack switching contacts is this: if they measure more than half an ohm, then they need cleaning. A low reading like 1 or 2 ohms may work, but that high a reading tells me they are dirty contacts. Always check your meter lead resistance first and keep it in mind.

[Chuck H]

Adding my +1 to all the jack info above. To address the original Q...

I assume the plan is to determine if the jacks connection to the board has been compromised, and if so to correct that and then improve stabilization with a big blob of silicone. Whether this is a good idea? I can only say, it can't hurt. I brought this up here once. I wanted to know if the plain ol' silicone sealant I could buy at the hardware store was appropriate for the job. And the answer is... Maybe? A lot of silicone sealants use some sort of acetic acid cure that is detrimental to electronics. So look out for that. "Silicone II" is a popular sealant that probably shouldn't be used because of this. If you're after high temp, which happens, you'll probably need a specialty product. Most silicone products will take a lot of heat, but if you need REALLY high temp, like over 1000F. And avoid any product with black pigment. To this day most black pigmenting is achieved with carbon. Repeated application of heat and high voltage can have an affect that on some black pigmented products that forms partially conductive pathways (like a resistor). So... A little research into whatever product you choose is a good idea. You want non acidic and not black. Because this question was about silicone it's probably also a good idea to avoid other "siliconized" products that aren't just silicone unless you can get specific information about their electrical properties.

[Enzo]

Plain old generic PURE silicone. As Chuck said siliconized is not it, and some caulking is only partly silicone.

[ron45]

[QUOTE=Chuck H;391267]Adding my +1 to all the jack info above. To address the original Q...

I assume the plan is to determine if the jacks connection to the board has been compromised,

Yes the part about acetic acid is something was unaware of as it applies to pcb. I knew there is plenty of it in plain old silicone. So thanks to you I will look into other non conductive blob solutions.

All the stuff about contacts mostly applies to places with high humidity. Not relevant here in New Mexico. But it's very useful to know the correct ohm readings for a mini jack. But is this reading with the T and R shorted S. possibly or some other combination possibly? Reading just the circuit involved might yield variable info.

Ron

[g1]

Oxidized contacts are a very common problem. They may be more common in high humidity environments, but they are also common everywhere else. They are not irrelevant in any climate.

[Enzo]

Agree^^^

Oxidation occurs in all climates, as does plain old dirt.

Never think up reasons not to check something.