3below

What was/is the plan/outcome?

Bough some Uke bass machine heads from Jez. Rapid arrival, well packed and excellent communication. Perfectly smooth transaction

One big plus in this situation is the pre-amp is on a board with 'real' size components which makes any repairs / modifications much simpler (and possible). Two things I would follow up: Check the continuity on the dead xformer, you might get lucky and be able to identify whether it is the HT (B+) or heater windings that have failed. This would give a pointer where to start fault finding. Detach the preamp from any follow on circuits and test it in isolation - is it a preamp issue or something further in the circuit.

Just got the bass seat in an originals prog rock band (steep learning curve). The Corvette fretless with Roto Tru Bass strings (no effects) just does the business and has impressed the rest of the band.

This would really help make any diy repair much easier. My diy way forward would be - find the chip, make sure it fits really well and superglue it in, if at all possible I would not glue right up to the edges of the chip at this stage. After allowing it to set, use ebony dust (make some with sandpaper) piled up into the remaining gaps and dribble thin superglue onto the dust piles, again allow to set. Sand level using a flat block using 180, 240, 320, and successively finer papers until you are happy. Any missing gaps can be rectified with more goes at the dust + superglue method. The early minutes of this video https://www.youtube.com/watch?v=RXIton7x6Q0 is where I picked up the method, it worked really well on the one refret I have done. Depending on how valuable the bass is, plan B is build up black epoxy in the damaged area and sand to shape or find a luthier.

The natural looked good, body joints well matched for grain. Like @PaulThePlug I am very partial to natural finishes or even better brown natural

All parts now re-assembled into the form of a bass. An excellent job by @Andyjr1515 with outstanding discussion of potential issues and options during the process.

Exactly the opposite here, Glasses on to read, rest of the time perched on head.

A really super clear explanation, well broken down and demonstrated Great work.

Bought a set of Schaller M4L machineheads from Ian. Super transaction, very fast arrival, well packed and great communication. Thank you very much, another great member of bc.

I have been using it on various bass builds and repairs with no apparent problems yet. Your point about high spec products vs cheapo stuff is well made.

An interesting page https://www.sciencedirect.com/topics/engineering/superglue I did not know that CA glue bonding is inhibited by acidic hardwoods e.g. oak nor that they are thermoplastic in nature and thus joints will creep over time when subjected to stresses significantly below the brittle failure stress or yield stress. You may be (or may not be) surprised to know that that cheese and superglue will show the same creep behaviour with aging time (I spent 3 years stretching thermoplastics in my ill gotten youth).

^This, plus, to help the superglue to wick in better, force the crack ever so slightly open - lever it with a nail in the adjuster hole? Screwfix do a low viscosity superglue at a sensible price. If you were so inclined to strengthen the repair, you could: Plan A: make up small aluminium or wood fillets (grain running lengthways to the crack) and glue this over the crack (both sides) or the hoseclip around the crack area idea or a few cable ties around the crack Plan B: Drill a through hole, taking care to miss the adjuster hole/insert, 4mm stainless socket flange head bolt, washers and nyloc nut. picture shows what I am aiming at

Bought some TruBass strings from Sean. Excellent communication, well packed and arrived faster than a fast thing. First rate transaction.

I suspect the two way truss rod has been turned anticlockwise a fair way putting relief into the neck (I have built a bass with such a stiff neck that I have had to do this). Slacken the strings, turn it clockwise a bit at a time (1/8 turn?), re-tune, assess relief. Keep going until you are happy with it. It will go loose then eventually feel tight as you start to counter the string tension. Prior to having an unfortunate experience with one of my G&ls I never slackened the strings when doing truss rod adjustments. These days I do following the advice of Jon Shuker who replaced the G&L trussrod and fretboard. I really rate my SWB-1, playabilty 5*, build quality 5* etc etc ..

It certainly gives a starting point for further experimentation, armed with the right kit

Bought a pickup from Andy. Well packed and rapid arrival, all is good. Fuss free easy transaction. Thanks

As I am now a rusty retired Physicist (and was cra*p at resolving forces, always found it difficult to draw the right diagram in anything complex) I would be interested to see what dimensions and numbers might apply to this problem. If we can identify where the effective centre line that the forces act about (in a simple model) then the bridge height and nut are easily identifiable. Body to neck heel treat as a rigid non bending body. Guestimate the tensioning cable length and distance above (below?) the effective centre line as per my earlier diagram and we might get some order of magnitude answers. In reality it not simple since the beam (neck) has finite depth and is not isotropic. Any takers?

Due to the complexity of the situation I wonder if an a priori calculation (finite mesh analysis? or first approximations?) is reasonably possible, I suspect it would be quicker to make the neck up and see.

You could try the Headway, set the impedance to active/ low. It may or may not work satisfactorily. You would still need an xlr (from mic) to jack cable.

I agree with your description and reasoning, as always a diagram helps clarify the situation