Rev's MK-2 Build

[Simon Barden]

I haven't got space for another large cardboard box - especially one big enough to get a glued-neck guitar in for its clear coats.

[Rev]

Humidity is too high today, so I just sanded off the rough spots that the primer brought out and cleaned up the oversprayed portions. Not too hard a job. Ill have to continue working on that when weather permits. The neck is waiting to be primered too, but not much I can do but keep supplies at hand and wait.

May turn my attentions to part of the wiring while it's damp outside. Here's a good question to throw out. I'm mainly used to working with rear routed guitars as opposed to ones with large pickguards. This kit's pickguard covers the entire pickup and control area. If I shield the back side of the pickguard, the pots will be touching the shielding - thereby providing ground, correct? So I should be able to skip grounding the pots and the pickup switch and jack, as theyll already be in contact. I just have to send the bridge and pickup grounds to a single spot...?

(When Ive done this before, I sent the ground to a screw and loop attached to the shielded body... no pickguard involved)

[Simon Barden]

In theory, yes. But you need to make sure that there is a good low-resistance path from every connection requiring a ground back to the ground lug on the output jack. If you rely on the jack socket body making contact with the shielding, then just remember that jack sockets have a history of coming loose over time - and if that happens there goes your ground connection and your output signal.

So if it was me, I'd certainly ensure there's one pot with it's back connected by a wire to the jack socket's ground tag as a back-up, just in case. You also need to check that the shielding material is making a low resistance connection to all the metalwork of all the pots and switches. Copper tape/sheet should be fine for this - just avoid anything internally conductive but with a non-conductive coating.

Shielding works up to pretty high resistance levels - I've seen a figure of up to 1 meg ohm being sufficient for that purpose - but you really want to get a good low resistance ground path if you can for the guitar signal. You really also want to avoid duplicate ground paths. And if you do use copper, because it has a different electro-chemical potential to the alloy and steel used for pots and sockets, if the area where the two metals join gets wet (e.g. sweat), over time you will get corrosion/oxidation and a high resistance connection.

Which is why I'd probably cut the shielding out around holes for pots and switches so that the shielding came into contact with just one grounded pot (or the jack socket body), and wired ground connections to the rest of the controls as normal.

[wokkaboy]

Hey Rev. I'd probably ground the pots and switch to be sure. Just earth to a common spot usually back of volume pot.

[Rev]

Ahh, I see. It might work initially but wouldnt stand up to wear and tear very long. Makes sense. Well, then, good, I don't have to really do anything different than I'm used to in that area.

[Simon Barden]

It would work, but long-term reliability would be a problem unless you had a rigorous maintenance regime and went round and tightened all the nuts say once a month. Soldered connections are much more reliable.

[Rev]

Did my touchup primer work after carefully wrapping newspaper around the porch railing. Had a single drip roll down the body when I stepped too close. Just sanded that out - although now I have to respray that section, it can wait for another day.

[Andy40]

Doh! yhep another day.....hopefully the humidity will stay down.

[Rev]

Had a brief window open up and finished primering the body. I was able to get a coat in on the neck, but I think I'll need to do it one more time - the can was getting low and the resulting coat is patchy.
The weather turned foul since then, so I did the pickguard shielding at the kitchen table. Trimming the edges of the copper off was fun with a young cat happily attacking the shiny tape.
Now I'll install and connect part of the components on the pickguard so they're ready to go at a later date.

[Rev]

Small problem. The included mounting screws for the mini HB are just slightly too long for the routed depth of the pickup cavities. Not by much.... about 5mm max.
Multiple solutions come to mind - I need either a shorter screw or a deeper hole. Off to see about shorter screws first.