73-28 Bass

[rv_bass]

Looks like the original hum canceler was embedded in the neck and exposed when the battery cavity was routed on the back. It is non functional and has one located between the pickups now.

[edwardofhuncote]

I would like to have been a fly on the wall in the shop when the plunge router hit that thing. I'm kind of wondering if it was an accidental. Like maybe they tried to move the battery box to the back of the bass per a customer request, accidentally hit the hidden hum-canceller, and therefore, had to locate it between the pickups.

[flavofive]

Holy cow!  Yeah, no joke - that is NOT what you want to see when you finish routing.
I suppose it's possible that they knew all along it was going to be "sacrificed" to get the battery cavity in the standard location, but if not, ouch.

[JimmyJ]

Wow, how about that?  It's like an archeological dig and you've unearthed the humbucker from when the Romans were building basses.    

I can't imagine that was done on purpose so it must have been quite a surprise and perhaps a disappointment when it happened.  But maybe they were planning to move the coil to the front anyway so...  That bass has some history!

Jimmy J

[pauldo]

The interrupted cut probably necessitated a router bit resharpening. 

But yeah, that is really a cool find!

[rv_bass]

The PF5 wires are quite old and very brittle. Each time I reconnect a wire another one would pop off when I reinstalled everything in the electronics cavity.  The bass has had quite a bit of modification to this point by others, so the bass will be updated with a new PF-6 and associated wiring harness. I plan on using this one a lot, so it needs to be reliable.  I will then take my time and restore the PF-5 by replacing every wire on it with new wires, restoring the PF5 functionality and reliability for future use.

[rv_bass]

Note to those considering replacing Q switches in older Series I basses that have the PF card mounted on the back of the cavity plate. 

The new Q switch design with snap on connectors are taller than the older Q switch components that have soldered wires, the result is the plate mounted PF card will not fit with the newer snap on connector Q switch components.  It looks like the new snap connector Q switches are designed for Series basses with the PF card in a separately routed compartment on the back of the newer Series basses. 

You can make it work with a little imagination though

[rv_bass]

With all of the mods and surprises by previous owners and my current restoration efforts,  I’m going to call this one my 73 Custom    

One more step remains, converting the pickup wires from coaxial to Molex two-pin, found these photos for guidance…

[JimmyJ]

rv,

You know that Alembic has coax to Molex adaptors right?  But you might as well go all the way with your Custom machine!  Note that in the two pics above the shield is in different positions.  I believe the lower picture is correct; shield on that side when looking at side of the connector with holes.   

Jimmy J

[rv_bass]

Thanks, Jimmy, I have seen pictures of the connectors and will look into those as well.  Thanks also for pointing out the differences in the images above, noted

I’ll post photos of the restored bass once completed and tested for functionality.

[rv_bass]

I am happy to report that this evening I finished resorting this bass to full functionality.  I had to add a little to its history of modifications to get the new Series I electronics to fit, but it works perfectly now and is a pleasure to play.  I will plug the extra original holes in the front of the bass with abalone-topped wooden plugs.  It’s a beautiful bass brought back to life.

[edwardofhuncote]

So cool to see this one back up and running. 

[JimmyJ]

Wow!  Great work rv!

That center board with the resistor array looks like a custom piece which makes the wiring harness more modular.  What's the story, is this the current factory package?  It also puts the Q switches in a vertical line instead of the 2 o'clock position relative to the tone controls.  But that just adds to the custom-ness of this lovely historic axe.  Very cool. 

Are you waiting on the mini-coax to Molex adaptors or did you change the connectors on the pickup leads?

What a great save!  So glad you've put the time, effort, and $ into reviving this bass.  I bet it sounds amazing!  Also thanks for keeping this thread going, it's been a treat to watch your progress.

Jimmy J

[rv_bass]

Thanks, Jimmy and Greg.

The Q switches appear to be a new configuration with individual circuit boards and clip on wire connectors.  I assume they are a new design since they are not the same as the 70s versions, but I do not have any basses newer than the 70s so not sure how long these Q switch versions have been around. 

I believe they are typically aligned horizontally next to the low pass filter knobs like they have always been.  But, the new Q design with the clip on wire connectors and mini circuit boards are taller than the old ones.  So, the brass plate cavity cover would not fit if I tried to attach the preamp circuit board to the back of the cover plate as is normally done on the older basses.  So, I had to find a way to insert the preamp card into the cavity with all of the other controls (I did not want to rout out a separate preamp compartment on the upper half of the body like on the new basses).  The only way I could fit the card in the cavity was to slide it up towards the lower horn as shown in the photo (I also slipped the board into a thin insulating sheath to prevent shorting it out, not shown).  To do this, I had to relocate the bass pick up Q switch up between the volume knobs.  Now it all fits and works great.  So it's my custom 73 bass (maybe a new design, who knows). Also, I changed the mini-coaxial connectors on the pickup wires to the two-prong molex connectors so that they would connect to the new circuit board, that was the last step that I finished last night (not shown in the photo).

The bass has a beautiful tone, it is lighter than others I've had, hangs nicely on a strap, and the neck has a great feel, plays wonderfully. 

I plan to completely rewire the entire original circuit and harness that came with the bass.  If I can do that and get it all to work properly I might consider putting that back in the bass sometime down the road.

[edwardofhuncote]

Hey Rob, if you have the clearance inside, a couple of these brass hole plugs might be an aesthetically blending fix for those three vacant holes. They are available in many sizes. For that matter, black plastic ones are too.