Extremely bizarre behavior of my StingRay Special

[Hypercaffium]

I've recently acquired a beautiful StingRay Special 4H in Dropped Copper. After a couple of weeks, I noticed that the signal was randomly going off and back on.

Symptoms:
What I heard when the signal was going off and back on is a peculiar "click".
That is the active preamp engaging when it detects an electrical signal going in (jack cable inserted with amplifier turned on).
If you unplug the jack cable and then plug it again, you hear that "click".
If you open the battery box and then close it, you hear the same exact "click".
That's because the preamp doesn't have power anymore and when it comes back, well... it does the usual "click".
So far so good, right? Bare with me.

Possible cause and solution:
I did some tests at home and unfortunately I couldn't understand how/why it was happening, so I've sent an email to EBMM and after talking with them I shipped my bass to my official local distributor, which also does repairs for EBMM.
They couldn't identify the problem and they said the bass worked perfectly and didn't show any problem. They talked to EBMM again and decided to replace the entire motherboard (with preamp, controls and all that stuff).
Well, one thing and another... I got my bass back after almost 3 months. But that's another story.
Unfortunately, I couldn't spend enough time with my bass when it came back home because I was traveling for work, but it seemed to work fine with the new replaced parts.
During this lockdown thing I finally got the chance to spend some quality time with it and guess what? It's happening again!
I must say this is not a rant thread, I just want to solve the problem asap. I'll contact EBMM via email and complain with them of course, but not here.

So... let's start excluding the replaced parts. I'm pretty sure it's not the preamp, the motherboard, or the controls. Everything has been replaced.
I think it's the output jack, so I started doing some tests with it. A couple of days ago I discovered some important things:
1) Touching/moving the jack cable doesn't trigger the defect. So the output jack port is not loose, maybe something is happening inside, definitely not outside.
2) If I play sitting, it definitely happens more often.
3) If I tilt the bass forward and rotate it around 90 degrees, I'm able to trigger the defect. The signal goes of (with approximately 1 second of delay) and then back on, and of course it "clicks". Imagine being on stage and tilt your body forward to reach a pedal in your pedalboard. That causes the problem. Why? I absolutely don't know.
4) The battery box isn't the culprit, imho. I tried to put a little spacer inside the battery clip to make the contact tighter in order to prevent a possible loose contact and nothing changed.
5) Angled jack cables seem to trigger the defect more often, but I'm not 100% sure.
5) If I use Proel cables, the problem disappears completely. With all my other jack cables, the problem is always there. Proel cables seem identical to my other cables but I guarantee you they somehow solve the problem. Why? I don't know.

I think it's the output jack, but what is happening? This is really strange and annoying. Never experienced something like that.
Please, help me solve this problem. I love that bass and I won't give up.

 

[RSBBass]

It sounds like the contact at the tip inside the jack is either dirty or a bit loose. If it is an open unit it is an easy fix. Get a cotton swab and some electrical contact cleaner and clean the tip where the plug contacts it. You can also bend it slightly to improve the contact. If it is a closed unit it will be trickier. Once again a swab and contact cleaner but it will be hard to see what you are doing. I have had some luck using a chop stick to bend the contact. Alternatively you can replace the jack. BTW while all plugs are supposed to be the same size, I have encountered variation. The one that works is probably a shade bigger making better contact.

 

[Turnaround]

My bet is that the problem is in the jack, probably dirty contacts. Was the jack replaced when the new electronics were installed?
And do any of your cables have gold plated plugs?

 

[Hypercaffium]

It sounds like the contact at the tip inside the jack is either dirty or a bit loose. If it is an open unit it is an easy fix. Get a cotton swab and some electrical contact cleaner and clean the tip where the plug contacts it. You can also bend it slightly to improve the contact. If it is a closed unit it will be trickier. Once again a swab and contact cleaner but it will be hard to see what you are doing. I have had some luck using a chop stick to bend the contact. Alternatively you can replace the jack. BTW while all plugs are supposed to be the same size, I have encountered variation. The one that works is probably a shade bigger making better contact.

I think I understand what you're suggesting. I'll post a picture of the jack asap, just to be sure. I think it's open though.
I can't see any difference with the other jacks, but I guess they're a little bit bigger.

My bet is that the problem is in the jack, probably dirty contacts. Was the jack replaced when the new electronics were installed?
And do any of your cables have gold plated plugs?

The jack was not replaced.
The cables that seem to trigger the problem have gold plated plugs, while those that work good don't.
So the problem is gold plated plugs?

 

[Turnaround]

The cables that seem to trigger the problem have gold plated plugs, while those that work good don't.
So the problem is gold plated plugs?

It is my belief, though many would argue the point, that gold plating on the plugs causes problems. A very large number of instruments that came to me supposedly needing a new jack only needed the jack cleaned. When I cleaned the jack a lot of gold "dust" came out that had adhered to the inside of the jack. Once cleaned out the jacks no longer crackled. I have been advising my customers for years not to use gold-plated plugs.

Your problem seems to me to be related to the jack, and since you have been using gold-plated plugs I would start by thoroughly cleaning the jack - not just the contacts, but also the barrel. However, the gold dust is hard to get off - contact cleaner often doesn't work - sometimes it requires some very fine sandpaper wetted with the contact cleaner. It may be easier to replace the jack.

 

[Hypercaffium]

I've always used those cables, I have three of them. That can be a cause, of course. I've also noticed how the gold plating is starting to wear out a little bit in some places. It's more noticeable in the angled jack (the one that I use the most because it goes into my basses). The straight side that goes to the amp looks still as new. I also tried to flip them and use the straight side on my StingRay but it still give problems. Maybe the dirt is inside.
I'll come back with some pics asap. Thanks.

 

[RSBBass]

It is my belief, though many would argue the point, that gold plating on the plugs causes problems. A very large number of instruments that came to me supposedly needing a new jack only needed the jack cleaned. When I cleaned the jack a lot of gold "dust" came out that had adhered to the inside of the jack. Once cleaned out the jacks no longer crackled. I have been advising my customers for years not to use gold-plated plugs.

Your problem seems to me to be related to the jack, and since you have been using gold-plated plugs I would start by thoroughly cleaning the jack - not just the contacts, but also the barrel. However, the gold dust is hard to get off - contact cleaner often doesn't work - sometimes it requires some very fine sandpaper wetted with the contact cleaner. It may be easier to replace the jack.

This is interesting. Gold should be highly conductive and inert. I wonder if they are using low purity gold with a lot of silver or other impurities that oxidize into non-conductive crud. I have never been a fan of gold plated cords as the the gold can't move any more electrons than the metal they are plated on produces. For them to be any use they would have to be solid gold,as wood the wire and the jacks.

 

[Turnaround]

Gold is the most electrically conductive of metals. And it does not oxidize. It can, however, cause galvanic reaction with other metals. The corrosion caused by such galvanic reaction is intensified by the conduction of electricity. In such cases it's not the gold that is corroding, it's the metal beneath the plating. I think what happens on the jack is that it gets a coating of corrosion mixed with gold particles, and that substance inhibits the electrical flow. But I do know that once you get that gunk, whatever it is, out of there the jack works as it should.

 

[Hypercaffium]

Here some pictures of the cables I used during the tests. I just want to remember you guys that with the non gold plated cables the problem didn't show up. If you look at the last picture, the gold plated cable is shorter.

 

[RSBBass]

Just look at all that crud on the gold plated one.

 

[Matt Liebenau]

Without having the cables in hand and a caliper it’s hard to tell but the bottom (chrome) plug in the last picture could be bigger then the other one which, in addition to the debris Turnaround mentioned, could cause a problem with the jack in the bass. That could be why it works better with that cable.

 

[Hypercaffium]

Just look at all that crud on the gold plated one.

That's not crud, believe me. I keep all my gear clean and well maintained and I don't like dirty stuff in general. The plating is probably just worn out, which can be a bad thing of course. Another thing I must say is that the other gold plated jack I used for the tests (not shown in the pictures) is completely new. It's a backup cable I never used. With that cable, the problem is still present.

Without having the cables in hand and a caliper it’s hard to tell but the bottom (chrome) plug in the last picture could be bigger then the other one which, in addition to the debris Turnaround mentioned, could cause a problem with the jack in the bass. That could be why it works better with that cable.

What do you mean with "bigger"? Bigger in diameter? It's certainly a little bit longer, you can clearly see that in the picture. Let me know if it could be useful to measure them, I don't have a caliper but I guess I can figure something out.

Thanks to both for your help.

 

[Matt Liebenau]

Longer could bend the tip contact out but I meant larger diameter. It’s an odd deal. There’s one or two brands in the US that have a slightly larger plug and after you use them for a while “regular” generic cables don’t work very well.

 

[Eddie LeBlanc]

I like Mogami

 

[Hypercaffium]

Longer could bend the tip contact out but I meant larger diameter. It’s an odd deal. There’s one or two brands in the US that have a slightly larger plug and after you use them for a while “regular” generic cables don’t work very well.

I'll try to open the jack tomorrow and see what happened inside. But I must say that I've always used the same gold plated cables and not the (bigger) chrome plated, so it's impossible that I somehow damaged the jack. I've always used the smaller cables.
This is really odd.

 

[Matt Liebenau]

For sure clean it like Turnaround suggested. It could be that also. It could be several things for that matter.

 

[moderatelyfunky]

I just had a strange issue with my new EBMM Sterling. The first symptom for me was a resonance that I couldn’t trace. I shipped the bass back to MM and they found some two incorrect screws and adjusted the nut. Didn’t seem like a smoking gun anywhere.

When I got the bass back, as I rolled it forward I heard a clunk. Rolled it back on its back, clunk. Turned out that the epoxy holding the pickup together had given up. I never plugged it in so, I can’t tell you what if any audio issues there might have been.

The rotation aspect of your description seems suspiciously similar so I just wanted to throw the pickup out there.

 

[Hypercaffium]

EBMM replied to my email and they will ship a replacement jack to me. I'll probably open up the jack tomorrow to see what's happening and post some pictures.

 

[bpc]

Pedant alert!

Gold is the most electrically conductive of metals. And it does not oxidize.

This is a common misconception. Gold is extremely reactive and will produce smoke if you grate it finely. The oxide of gold is extremely stable and that is what you see when you look at a bit of gold, a molecule thick layer of gold oxide, which is an excellent conductor. I think the fashion for coating connectors with gold is because the surface doesn't tarnish, because it is already oxidised. Everything else you say is true. In fact the glavanic reaction is due to gold being highly reactive in its non-oxidised state.

I've used lots of gold plated connectors on hifi equipment but these are usually phono plugs and they are rarely removed and re-inserted so this problem doesn't arise. I don't have any gold plated guitar leads so I've never experienced this but what you say about the coating coming off as dust makes perfect sense and I'll be sure to never buy gold plated guitar leads, so thanks for that bit of info.

 

[Turnaround]

I understood the term "oxidation" to mean reacting with oxygen. According to information I got from the University of California "Gold does not react with oxygen at any temperature and is one of the least reactive chemical elements". Strange that.