Series 2 electronics - 3 issues: squeal; worn selector switch; LEDs

[lozbass2]

Hi all,

I'm hoping that the collective intelligence on here can help me out.  I have a Series 2 fretless from 2007.  I've been playing it a lot recently but it has 2 faults and an LEDs issue.  I'd really welcome any advice.

1. Squeal - in the past two days, the bass has developed a pretty horrific, high-pitched squeal.  It appears to be the treble CVQ that is the cause.  At either end of the full travel clockwise and counter clockwise on the CVQ control, the squeal disappears (mostly), but for around 90% of travel, the squeal is present.  The pitch of the squeal changes as the CVQ is rotated.  The pitch also changes if I set the CVQ anywhere along it's travel (apart from fully open/closed) when I rotate the treble filter.  It's not really relevant (I think), but the vol, CVQ and filter nearest the neck actually control the treble bridge pickup - both my Series 2 basses were wired this way when I received them and I'm used to it now.  I've read Jazzyvee's post on squeal and I'm trying Jimmy J's 100 rotations advice now.  I had the squeal problem a few years ago with a Series 1 too - the multiple rotations idea eased the problem but it kept returning.  So, if the rotations trick fails in this instance, are there any other possible fixes, or am I looking at a new CVQ control, or something else?  For context, I'm recording at the moment and really can't afford the squeal susceptibility - I really need the bass to be working as it should.

2. Pickup selector (4 position) - I'm afraid that I have a problem here too (please see images).  I noticed that as I turned the selector, it was moving more than it should (without clicking over selections).  I tried to tighten the nut under the knob and this worked for a few minutes, then the problem returned and travel of the switch assembly itself was evident.  I removed the Grayhill rotary switch inside the cavity and noticed that the top of the screw thread is worn - this appears to be why the nut is slipping.  I can order a new Grayhill 50C36-01-2-04S rotary switch here in the UK for around $45 but then would have the hassle of de-soldering and re-connecting (and this would probably need the attentions of a pro - my iron isn't so fine-tipped).  I've attached an image - are there any engineers out there that can suggest a fix that doesn't involve a new rotary switch?  The amount of thread available as the switch shaft protrudes through the hole in the face of the bass is pretty shallow and there appears to be a metal washer-like insert below the hole - in the cavity - that would preclude careful removal of a little more wood, and reducing the thickness of the facing wood is a perilous/undesirable exercise anyway!  The only thing that I can do at present is leave the selector in position two (both pickups on), then control the bass using the individual pickup volumes - even that's not particularly useful just now given 1 above.  All that is holding the selector switch in place at present is the knob fixed to the shaft.

3. LEDs - hopefully a simple one!  When I received the bass, the previous owner had found the fingerboard edge LEDs a little too bright.  He'd had somebody insert a few resistors (?) in the sheath visible in the image to dim the LEDs (again, please see the image).  To reverse this mod and restore the brightness, is it OK for me to simply remove the sheath, cut the red and black wires and then carefully re-connect and insulate them without the resistor arrangement?

Any ideas really would be very gratefully received - as it is, the bass is pretty much out of commission.

Cheers, Loz

[rv_bass]

Here are my thoughts:

1. Rotate all controls fully clockwise and counter clockwise 50-100 times (i.e., exercise the controls).  This should clean them out and usually resolves squeal issues.

2. Are you sure it is not the plastic pointer switch slipping on the selector switch shaft?  That has happened to me a few times.

3. I don’t have the knowledge to comment on wiring, but if the LEDs work at the current intensity you might consider leaving as is.

Let us know how it goes, others will chime in with good advise as well. 

[JimmyJ]

Hey LoZ,

(rv beat me to some of these answers but here's my spin anyway)

Sorry to hear you're having these troubles with your bass.  Let's see if we can help with some ideas...

#1.  The dreaded squeal.  The "rotate 100 times" rule applies to the both the CVQ and filter controls which work together to do their thing.  It's harder to sweep those pointy knobs but ALL of the pots need to be swept clean to avoid the oscillation.  Do your volume knobs too.  Let us know if you have any success taming this issue. 

#1b.  That's odd that your controls seem to be backwards.  Does your pickup selector turn on the bridge pickup first?  If not, your pickup inputs may be swapped at the preamp board.  Take a look to see if the color coded dots, or "B" and "T" seem correct at their preamp board connections.  The only thing is ... if the bass has had the low-noise mod you would want to be sure it was done the right way around or the noise level could be effected.  And the volume trim pots will also be swapped.

#2.  This is a bother!  The p/u selector switch is the most used control on our instruments.  At least for me, it's thrown between every song.  And because yours is mounted in the wood the threads are barely peaking out far enough to hold it securely.  Have you tried replacing the nut?  Perhaps that has one worn thread too and a new one would be enough to grab on?  Or turn the nut over in case it's just one side...  Also, if you are able to get it securely seated even for a moment, you could use a drop of Blue locktite between the nut and shaft threads to hold it in place.

I don't think you want to remove any wood from inside to bring the threads further out because, as you say, that is precarious. 

And replacing it with a brand new switch would be quite difficult.  (Look at those tiny jumpers between only some of the poles!)  In my 40+ years of playing Series basses I've only ever had one p/u selector switch fail.  But because of that I carry a pre-wired one among my spare parts.  Much easier to replace when that fine soldering at the switch has already been done by the factory!  So you could inquire about buying a pre-wired selector switch from Alembic but it will be expensive and a painful way to deal with .003" of worn out threads.

In the meantime, I think your idea of leaving the switch in the "both" position and using your master volume (I believe you have one) for muting might be your best route.  You probably know this but if you do that you must be very careful to have the amp and or DI disconnected before you plug in your 5-pin cable because that will send a full volume THUMP down the audio lines.

#3.  Hard to see in your pictures but that is clearly somebody else's mod on the LED leads.  There should be one LARGE resistor coming off of the 5-pin jack which is to drop the voltage down to what the factory sets.  I think I can see this right down near the pot - its leads will be fully shrink wrapped and secure as per Alembic specs.  Any additional resistors - most likely under the black tape inside the un-shrunk shrink tubing - could probably be removed.

Hope you can this bass back into ship shape!

Jimmy J

[StephenR]

The other option for the LEDs would be to order the trimpot to adjust the intensity that Alembic uses and have the existing mod replaced. My bass came with no on/off for the LEDs and no trim pot, it was very inexpensive to have Alembic put the trim pot in so I doubt the part itself would cost very much to order. FWIW... I also found the LEDs too bright before the trim pot was added, if you remove the mod you may also find they are too bright. Mica said recently that it is now standard for them to add the internal trimpot to new builds.  Good look with the squeal I experienced this once with the pickup selector and rotating it a bunch of times cleared it right up.

[JimmyJ]

One more thought about the p/u selector switch.  On a standard installation where the switch is located on the lower horn, it's mounted on a brass plate.  I presume that's mostly because the horn is not accessible from the back so the only way to get the switch into place is to mount it to the plate then mount the plate over the larger hole.  But also, I believe the hole in the brass plate has one flat side which matches the switch shaft's flat side and locks the switch's body into position so it can't rotate.  In other words, the hole is "keyed".  The hole in the wood where your switch is mounted is not keyed so the switch has nothing to help it resist rotating except for the single mounting nut.

I'd be curious to hear if others with the p/u selector switch mounted in that position have had similar issues.  And/or if there are any tricks used by the factory to "key" that mounting hole.  For example, do they ever somehow use a rear plate inside the cavity?

Jimmy J

[jazzyvee]

I have the same issue with my series 2 PU switch, the threads on the pot shaft have lost their grip and tightening the nut just strips them. I have a spare switch from my box of auction worn spares but resoldering without a fine iron is going to be a challenge.
So for the moment i am leaving the switch in both pickup mode and using the master volume for off. i may have to take it to Jaydee for them to replace the switch. 

[lozbass2]

First, a massive and very sincere thanks for all the expert and incredibly helpful/creative input - I really do appreciate that the community here takes the time to respond with very positive and thoughtful suggestions and solutions.

Just a very quick update with more to follow and some detailed responses to suggestions:

For now, I've decided to focus on problems 1 and 2 - these are the issues that imply that the bass is functionally out of commission.  The LEDs are not actually 'broken' and are sufficiently bright to use in pretty much any real-world situation.  It's probably a good idea to leave them for now and return to address a reverse of the mod when the more important issues are resolved.  The only practical problem with the LEDs is that the mod implies more 'mass' of materials inside the cavity, and the latter is pretty cramped anyway.  However, thanks again for the very useful suggestions - the internal trim-pot sounds like a great idea and if I can install this (or have it installed) with Alembic-supplied parts in the UK, then probably something to consider carefully.

Squeal - I had a further look at this last evening and followed the advice re: the turning all the pots many times.  Probably a little ridiculous but I hadn't considered the interaction between the volume, CVQ and filter pots.  After around ten minutes of rotating everything - a good opportunity to catch-up on the day's news - I tried the bass again.  Unfortunately, a very minor impact on the squealing, if anything.  I had a very careful look inside the cavity, not that I really have the expertise to recognise anything, and checked for pressure on connections, loose connections - as mentioned above, there's a fair amount of material/components in the space and it's fairly crowded.  As I was looking around, I just let the bass squeal, though at very low volume in order of keep the neighbourhood happy.  As I was very carefully fiddling, I noticed that touching a component attached to the cvq (I'll provide an image later) made the squealing louder and more pronounced.  Then I noticed that - very carefully repositioning the component by pushing it back a little - made the squeal disappear completely.  Sort of very good news but I haven't got to the bottom of the issue yet.  Maybe a poor connection/joint or maybe something else - I didn't have good light and didn't have a magnifying glass.  I'll take another look in the next hour - the light is little better in the North of England this morning but at least I have a glass.  I'm hoping that just moving the component a little is an easy and reliable/durable fix!

On a related issue of the reverse connection of pickups/controls, I haven't had a chance to look into this but will do as soon as I can.  Again, thanks for the advice, I'd become accustomed to the control layout but hadn't considered the potential negatives of operating the bass this way...I will now!

Pickup selector - some fantastic ideas here and I had a Brown Bass with the selector on the lower horn - I didn't disassemble the bass at all so hadn't realised there was some kind of key.  What an excellent idea and possibly something that could be fitted/retrofitted with the non-plate series basses.  As you suggest Jimmy, some of the fixes are very expensive and it's a little galling that all I really need is about 1/12" inch of thread.  The problem is definitely on the switch housing - there's some corrosion and it appears that the body of the switch isn't particularly robust.  I've just received some Loctite Blue (medium strength) and will try that later, however, the key idea sounds like an excellent one.  I'll think about how it might be possible to create something here.  An alternative - this came to me during the night - is to approach my sister-in-law.  She's an excellent engineer with a well-equipped workshop - she makes her own diving gear (which requires tolerances and quality control of a level even beyond those found in the bass world!).  I'm considering asking her to make a threaded tube with a collar - a threaded insert that is sufficiently slender to fit down the hole to grasp the remaining thread on the switch, with a nut-like collard that will fit above the face of the bass and hopefully lock the switch in place.  Jimmy, if all goes wrong/fails, then the pre-wired switch, though an expensive option no doubt, sounds like the way forward.  The soldering is way beyond my capability!

Stephen, Jimmy - thanks again for your generosity - some excellent input!

More soon on developments and outcomes,

Cheers, Loz   

[lozbass2]

Thanks too Jazzyvee - clearly not an isolated problem with the switch!  I'd not thought of Jaydee - we have some good luthiers in Manchester (notably Jack's) but if I can find a way of retaining the existing switch, it's probably more cost-effective - and I'm a little piqued that it's just 1/12th of an inch of thread that is keeping me from calm satisfaction.  Jazzvee, if I need to go down the route of asking my sister-in-law to produce the necessary collar/threaded tube component, I can ask her to make a few - there may be more of us on here with the same problem.

Cheers, Loz

[JimmyJ]

LoZ,

Great troubleshooting!  I think you may have fixed your squeal.  I don't completely understand the filter circuitry but it's pretty clear that these components all interact with each other and are only a breath away from being great oscillators.  So let's say for example that when the mod was made to your LEDs and the backplate was reinstalled, it caused one of the caps to be pushed too close to the CVQ pot.  That contact, or even proximity, could be the cause of your issue.  Seems very possible!  I doubt any of the solder joints are the problem but any components touching each other certainly could be.  That's great!

I was trying to think of a "collar" kind of nut that would work for that switch but couldn't imaging one existed.  But if you have a machinist in the family (!!) that would be a GREAT idea!  There would likely be a market for a run of those right here in the forum! 

Another thought I had was for a thin metal piece (not brass) that would have 3 holes in it.  Two for the individual pickup volume pots and one "keyed" for the p/u selector.  This could be inside the cavity between the silver paint and these 3 components and would lock the selector switch in one position.  But those components are also slightly countersunk into the top material so I'm afraid this idea would move them even further into the cavity and make the situation worse.  Unless the switch could be mounted ONLY to that plate...  Still working this out in my head.  Ha!

Keep us in the loop!

Jimmy J

[jazzyvee]

If you go for a pre wired switch solution, let me know and we can share the costs of shipping and taxes. Jimmy, does a pre wired switch come with tails that you solder on to the matching  wires after cutting off the existing switch cables in the bass, or is it a full loom that you install via connectors?

[gtrguy]

I am right now getting ready to modify a collar nut on my TAIG micro lathe for my Alembic jazz bass 'varitone' circuit switch. If I was making one up from scratch I would use brass, since that metal is good for cutting threads in.

[JimmyJ]

Jazzyvee,

Prewired with the correct colored wires cut to "standard" lengths, lovingly shrink-wraped, and even with pre-tinned ends.  It could be spliced in but it seems like you'd want to actually connect these leads to their termination points for best results.  Again, the switch itself is not prohibitively expensive but the labor involved in prepping it must be substantial.

David, that's very cool.  I feel like we're on the brink of solving this pickup selector switch placement conundrum. 

Jimmy J

[lozbass2]

Hi all,

again, thanks for some extremely useful suggestions and advice - just to update:

1. Squeal - the squeal has disappeared completely.  I suspect that it was some interaction between the wiring to the cvq control and a component (a small red unit) that is connected to both the cvq and the filter pot.  I've included an image below.  When manipulating the wires from the pickup wiring ribbon - particularly the light grey and white wires - I noticed initially that the squeal changed and intensified.  I also noticed that there seemed to be some interaction between movement of the wires and the red component.  By very gently pushing the red component back a little in the cavity, the squeal disappeared.  As noted above, the cavity is a little congested and the insertion of resistors in some heavy plastic shielding to dim the side LEDs has exacerbated the congestion.  I have now trimmed the clear plastic tube that houses the LED mod and it's a little less cramped in the cavity.  I replaced the backplate over the electronics and tried the bass - it appears to be operating perfectly and is squeal free (and very quiet in terms of any hum).  I'm not sure if this is a fix that would work on other squealing series basses but possibly worth some very gently manipulation of wires and adjacent components - maybe the insertion of some shielding material in there would work too but it's usually a bit crowded in there.

2. Pickup selector rotary switch - some brilliant suggestions/ideas here and gtrguy, it appears that we were thinking along exactly the same lines, though you have the equipment and skills to bring the collar nut to life.  I'll be speaking to my sister-in-law this evening, though she is up in Scotland and actually taking measurements and designing/producing the item will take a few months as my brother is in Scotland and I'm in Northern England.  The mounting hole for the switch isn't that wide in diameter so any retaining collar will need to be fairly slender.  I tried Loctite blue last evening and it appears to have worked.  There was just sufficient thread on the switch to permit the nut/loctite to grip.  I'm not sure that it's a lasting solution so plan to go down the path above (if feasible) to have some collars made.  I'm not sure of cost - my sister-in-law is an extremely well-paid consultant engineer (she designs railway systems) and paying for her time may be prohibitive.  Maybe Mica and all would want to take a look at the collar idea if failed switch housings are a common problem?  For now, great to have the option to select pickups, though I'm not sure I'd rely on the switch in a live setting.

3. LEDs - I've decided to leave the resistors/dimmer system in place (rv-bass, I'm taking your advice here - thanks) - I know that the side LEDs in my other series bass are extremely bright.  Now that I've trimmed the plastic sheath that holds the mod, I'm hoping that the extra space in the cavity will preclude further squeal issues (though I'm not sure that the extra material in the cavity was the cause of any pressure on components). 

4. Control and pickup placement - a really weird one - I checked very thoroughly yesterday and the pickups are connected as they should be and all the electronics/connectors appear to be in the right place (T to T, H to H etc. on the board).  I balanced the pickups whist I was in there.  However, and it may just be my hearing/imagination, it does appear that the treble controls adjust the neck pickup and the bass controls the bridge pickup.  I've no idea what has happened here but the bass sounds pretty fantastic anyway.

So, again - thanks all - some very much appreciated inputs and ideas and we appear to have found a fix to all the original problems.

Whilst I'm here - and germane to the discussion of custom fixes - I've included an image of a mounted pickup cover logo that I had made for the fretless.  When I received the bass, it was pretty much mint other than the gold lettering on the bass pickup cover was fairly worn (not a look that I find attractive in any way, though I suspect it's an issue to very few of us!).  I tried all sorts of routes to having the logo replaced (Mica even suggested that the cover could be cut away and the pickup re-housed in a new cover - though a potentially dangerous approach), but then found a brilliant modelling company in London.  They were able to print a sheet of pretty much perfect logos that are easy to apply.  The work required to remove the old logo completely and refinish the pickup surface takes a bit of patience, but I've been pleased with the result.  I did suggest to Mica that I could supply these logos to other Alembic owners with the same wear issue but didn't receive a response.  I didn't wish to upset anybody or infringe any IP so the idea didn't go any further.  Just a note I suppose, that there is a decent fix to the issue of logo wear.

Again, thanks to all and I'll update with any news re: the nut collar. 

Cheers, Lawrence 

     

[pauldo]

I am right now getting ready to modify a collar nut on my TAIG micro lathe for my Alembic jazz bass 'varitone' circuit switch. If I was making one up from scratch I would use brass, since that metal is good for cutting threads in.

David, that is VERY nice.  My career has changed and I no longer have access to machining equipment.   I miss the creative aspect of turning and milling.

[gtrguy]

Beautiful bass! Yes, having a couple lathes of various size really helps with custom work. I love my TAIG micro lathe with a Unimat milling machine setup for small work.