Alembic Guitars Club
Alembic products => Owning an Alembic => Troubleshooting => Topic started by: rickstevenson on February 14, 2023, 10:47:12 PM
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I have a Europa 5 that has been sitting in its case for several years. I put a battery in it (it was stored without one) and it mostly works but makes a lot of extraneous noises - muffled crackles, humming and sometimes rhythmic ticking.
I opened up the control cavity and there is nothing visibly wrong except for a loose wire. It's a black wire with a white stripe, one of a twinned pair that comes from the direction of the pickups. The end of the wire has been stripped of insulation and is clean copper with no solder residue. In the attached pic you can see the end of the wire just to the left of the connector marked "3079".
Any suggestions for where the wire should go or other ideas about troubleshooting appreciated! I have made several attempts to contact Alembic directly over the past couple of months but without any success.
Thanks,
Rick.
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Extra info: I don't remember where the wire was actually sitting when I opened the cavity. The connector marked 3079 has 5 pins on the PCB and only 4 wires going into it, so that might be a big hint. There's an empty hole in the connector where a fifth wire could go but there's no pin in the hole and I didn't see any sign of a loose pin in the cavity. A wiring diagram would be really helpful!
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Rick,
We're happy to hear you are reviving your Europa!
Since the bass has been on an extended vacation ... the first thing I would suggest is exercising all switches and pots, like 50 cycles each. That action alone will often clear up noise issues.
I don't have any basses with Europa electronics but photos I've seen of others do NOT have that black/black-white wire. I don't think that is stock so curious as to what it might be. Also in the photos there are only 4 wires in that 5-pin connector so resist the urge...
Somebody with better knowledge of your electronics package will help out here soon. Meanwhile, could you post a pic of the front of the bass so we can see if there is anything unusual?
Jimmy J
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Thanks, Jimmy J! I'll grab a photo of the front and post it in the morning. It's bedtime here.
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Yep, I have never seen 'zip cord' used in an Alembic. I would trace it down. I wonder if it was an attempt to ground the bridge to something? Where does its twin go to?
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Maybe someone else with a Europa can post a picture of their electronics cavity for comparison
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Meanwhile, could you post a pic of the front of the bass so we can see if there is anything unusual?
See attached. I think all the controls are standard.
Yep, I have never seen 'zip cord' used in an Alembic. I would trace it down. I wonder if it was an attempt to ground the bridge to something? Where does its twin go to?
That could be it. The other wire in the pair goes to the input jack. Pic attached.
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I wonder if it is soldered to the underside of the sustain block. But that still doesn’t explain the clean bare end of the loose wire.
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Can you lift the pickups and see where the wires go?
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Thanks for the pics. Nice looking bass!
Right. That is probably the answer, somebody trying to "ground" the strings. I wonder what they did on the other end of that wire? If you lifted out the bridge pickup we'd probably see. (rv responded while I was typing - it could be that whoever did this may have just grabbed whatever wire they had handy.)
I'm fairly sure that on our basses that "grounding" scheme doesn't do anything, unlike on certain other passive instruments. Correct me if I'm wrong. But the evidence is that if there was a benefit to doing that Alembic would do it on all their instruments.
The more likely situation is that somebody was trying to correct what they thought was a ground issue but was actually RF being heard by the pickups which I believe are more sensitive and hear a wider frequency range than your typical passive bass pu.
At the same time, it probably doesn't hurt anything so we should concentrate on fixing your other noise issues.
If exercising the controls did not clear up the sound then try to isolate if it is coming from only one pickup or both. Pan fully one way or another and see if one pickup is cleaner than the other. Put the switches into the center or "flat" position, then try boost or cut... etc... Maybe you can isolate which part of the circuit is causing issues.
Let us know!
Jimmy J
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Just an added comment to Jimmy’s suggestions, I recently had to exercise pots and switches fully a couple hundred times each to clean them all out on an instrument that was not used for quite some time prior to that.
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Thanks for all your help, JimmyJ, rv and gtrguy.
Looking under the bridge pickup, the black twin cable does indeed head down in the direction of the bridge so, as suggested, it does appear to be a retrofitted attempt at earthing using a random cable. I have taped over the exposed copper on the loose wire for now.
I worked all the pots and switches and the noises (which sounded a bit different today) have almost all gone away. For a while there was still a little hum that was attenuated if I touched the metal surround of the input jack but that has stopped now. I also had a couple of bursts of crackling but after playing for a while that seems to be gone too. I'll see how it goes over the next few days but the results seem promising so far!
One other data point: while the noises were present they didn't appear to be affected by the position of any of the pots or switches.
Thanks,
Rick.
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I would remove the unnecessary DIY grounding wire.
Bill, tgo
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I would remove the unnecessary DIY grounding wire.
Thanks, will do that in a day or two. I didn't want to mess with too many things simultaneously and not know which ones made a difference.
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Thanks, will do that in a day or two. I didn't want to mess with too many things simultaneously and not know which ones made a difference.
Wisdom. 👍🏼
Just tossing this out there… how is your instrument cable? I have a 3’ Monster cable that I use when I hunker down in the basement. Recently it exhibits nasty noises if it is turned in certain directions (no more dancing and playing until I get a new cord).
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Just tossing this out there… how is your instrument cable? I have a 3’ Monster cable that I use when I hunker down in the basement. Recently it exhibits nasty noises if it is turned in certain directions (no more dancing and playing until I get a new cord).
Thanks. I did try a couple of different cables but the noise was the same. I also tried a couple of different amps just in case it was a weird interaction.
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Well, it's not actually fixed. What's happening now is that every time the bass is plugged in, it makes intermittent bursts of the same sort of noises (hiss, crackle, wind in the trees) for a few minutes and then it (mostly?) stops. If I unplug it for a brief period and plug it back in again it does the same thing again.
Another thing I have noticed is that the sound effects are affected by most of the controls - volume turns the noise up and down, the filter pot and tone switches vary the tone of the noise. Pan makes no difference.
I'll be away from the bass for the next couple of weeks but any helpful suggestions would be appreciated!
Thanks,
Rick.
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Sorry to hear it's still acting up. The fact that all the controls seem to be working correctly despite the noise points to the final stages of the circuit. But I'm not familiar enough with this preamp circuit to know what that means.
The next thing I would probably do is plug the bass in with the back panel off and poke around in there with a plastic or wooden piece (just not metal) to see if I could find a spot which makes the noise happen. Check closely around that pair of switches (under your mystery wire) which have so many components hanging off of them to be sure no un-insulated wires are coming into contacting the switch cases or the shielding paint. (Doubtful because Alembic takes all this into consideration). Also be sure the metal cylinder "choke" is not moving around and able to contact the switch or any other components.
Also, obviously, the 1/4" jack has got to be working solidly so if moving the plug around creates the noise then it might simply be corroded jack contacts.
I think we're getting closer. ??? Let us know what you find when you get back to experimenting.
Jimmy J
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Thanks, JimmyJ. Will have a poke around when I get home in a couple of weeks.
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I'm a bit late but my thought is the loose wire was placed between the back plate and body in an attempt to ground the back plate. This should not be needed as teh back plate and cavity are coated with conductive paint and grounded through the component mountings.
The way you describe the noise I suspect a component problem as if it was an intermittent connection or poor solder joint I would not expect the noise to go away after being plugged in for awhile and not come back. In the mean time if you haven't already done it I would reseat all of the connectors and look for bad solder joints. I would also get some Caigs Deoxit and spray the 1/4 inch connector contacts while exercising them. Just be careful and protect the finish from overspray.
If push comes to shove you can always send the electronics to Alembic for testing. If they find something wrong they can give you an estimate of the repair cost.
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Good ideas from Keith.
Yes the bare wire was probably just that, an attempt to ground everything which is already grounded...
Also a good idea to reseat the connectors. Each one has a small latch locking it in place. (See the pic). Not much force is needed to release it but that's how they work. And they'll snap back in place when you reconnect them.
I would be surprised if you found any poor solder joints! But I am voting for an issue with the 1/4" jack. Note that the mystery wire was hastily soldered to the ground lug of that jack which means it could have been overheated and messed with the contact tolerances... Not to mention possible in-the-closet-age-related corrosion. Wiggle that plug and see if that doesn't make a racket.
Let us know when you get back and have time to experiment.
Jimmy J
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In the next couple of weeks I'm hoping the new Europa circuit with an even better RF filtering will be available. This is something that Ron and Tom have been working on. It does sound like a capacitor failure and those Switchcraft barrel jacks, while the best available, only reliably work for 5-10 years. That's why it's supplied with a modular connector and the spares are sold in pairs, because if you're replacing one, it's best to have a spare in reserve.
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Thanks, keith_h, JimmyJ & mica.
I did reseat the connectors and have tried wiggling the 1/4" jack (it doesn't make any noise.) I haven't pulled out the preamp board and had a close look at it yet but I'll do that when I get back home. Maybe there's a swollen electrolytic cap I can't see from above.
I also have some Deoxit so I'll clean all the contacts.
Cheers,
Rick.
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All the modular connectors are gold plated. The pots are sealed and the switches are epoxy sealed. There's not much for contact cleaner to do in there - it won't hurt anything, but it's not likely to help much either.
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All the modular connectors are gold plated. The pots are sealed and the switches are epoxy sealed. There's not much for contact cleaner to do in there - it won't hurt anything, but it's not likely to help much either.
OK, thanks.