1977 4002 in Mapleglo

[Kopfjaeger]

Well after a week in limbo due to Hurricane Sandy's impact on my area, my newest acquisition finally arrived from the "motor city". As most of you already knew, I landed myself a project off of eBay a few weeks back.

I have to say it's not as bad as I thought it was but then again, I've never done the work required to fix her ailments so my assessment may be premature.

I've not yet separated the pups from the circuit to see it they are viable. I have a few questions before I separate them. As I expected, the bridge pup has an extra set of wires that go directly to the D.I. Does it matter how I measure this one?? The treble pup. do I measure between black and red??

OK, as I suspected, the body has a bit of separation from the neck. The upper section is worse than the lower. It appears someone widened the treble pup route, not sure why. The fretboard is shot. Not only is it cracked, slightly so, but it looks as though someone attempted to pry the frets off her and in doing so, the wood adjacent to the frets pulled up. The frets are all un pryed, though. The neck binding is all gone. I think I could get away with the slight linear crack in the ebony but the other damage I think sinks the board. Hey, Mr. Hall, you wouldn't happen to have another bass length piece of old source ebony laying in the wood room, would ya??? Please email me if you can hook me up!!

The thing that worries me is the neck. It appears the neck has had a bit of separation and has been repaired. The shedua strip is slightly raised as compared to the surrounding maple. There is a void between it and one of the maple sections that looks to have been filled with possible crazy glue.

The pick guard is in pretty good shape except for the two chips in it at two different screw holes. it seems way more rigid than the replacement on my other 4002.

Please take a look at my fotos and let me know what you guy think. I'm very curious to get your reactions and thoughts.

Sepp

Real nice right?? Yeah, hold onto your seats, it gets way worse!!

OK, a little rusty but not too bad

Yuk, what a mess

Good foto of the body/neck separation

Neck void neat headstock

Yeah, that's how deep and wide the separation is!!

[rickenbrother]

Congrats on the acquisition and have fun with the restoration. It's worth doing!

[jps]

Measure the low impedance wiring directly across the two leads that go to pins 2 and 3 of the XLR connector, I assume there is no transformer between the pickup and the connector?

The neck looks like it was re-fretted at some point, that tear out at the edges of the fingerboard seem to be from pulling the old frets out. The new frets look pretty funky to me, from that one photo you posted.

The separation of the body wings can be dealt with, consult the usual folks.

My guess is the bass once had a Gibson mudbucker in it.

[Kopfjaeger]

Jeff,

Measuring at the XLR will only give me the bridge pup, right? Since the treble pup is not hooked to it. I've never measured ohms on a pup before.

Thanks Joey, I think it is a worthy project as well!! I'd love to bring her back to where she needs to be.

Sepp

[jps]

What do you mean by "Since the treble pickup is not hooked to it"? The treble (bridge) pickup is the only one that should be going to the XLR connector. The best way (most accurate) to measure a pickup is to disconnect it from the rest of the circuitry and place an ohm meter across the leads, make sure it is set to read DC resistance (Ω); if the meter is not auto-ranging set it to the 10-20KΩ-ish setting, at least that is what is on my Fluke 8000A meter (20KΩ), your setting may vary.

[Kopfjaeger]

Nope, you are right. The bridge (treble pup) is the only one going to the XLR. I guess I need to refine my nomenclature. If the bridge pup is called the treble pup, what is the other pup called?

I'm told both pups are dramatically different in values. Not sure what model my Fluke meter is but I know I'll be able to tell if they are good or not.

Sepp

[jps]

Neck pickup (mid in the case of the 4002). Do you have the schematics for the bass?

http://www.rickenbacker.com/pdfs/19513.pdf

[johnallg]

Cool project, Sepp. The XLR wires should be low impedance, a low reading on the ohmmeter. The other winding from the bridge pup will read in the 10-20k range, as will the neck pup wires. The bridge has two windings, a regular humbucking and a second winding intertwined with it that is a lot less windings to give a low impedance feed for direct-to-board recording.

[Kopfjaeger]

OK, potentially good news. The XLR ohm reading, taken at the connector is 696. The red & black wires, still attached measure 7.48 on the bridge pup and 7.85 on the scenter pup. Since my Fluke 77 was auto ranging, I imagine the 696 is a .696. That puts me right in there, correct?? Do I ned to pull the pups out of the circuit? I measured them where the leads attach to the harness and pots.

Sepp

[admin]

Excellent news Joe.

[cjj]

OK, potentially good news. The XLR ohm reading, taken at the connector is 696. The red & black wires, still attached measure 7.48 on the bridge pup and 7.85 on the scenter pup. Since my Fluke 77 was auto ranging, I imagine the 696 is a .696. That puts me right in there, correct?? Do I ned to pull the pups out of the circuit? I measured them where the leads attach to the harness and pots.

Sepp

Your meter should tell you what range it's in, ohms, k ohms (x 1000) or M ohms (x 1000000).

696 most likely refers to 696 ohms, which is right in the ball park for an XLR circuit (nominal impedance for XLR is 600 ohms), so this is good. The 7.48 and 7.85 are most likely 7.48k and 7.85k ohms (7480 & 7850 ohms), which is probably a reasonable value for the other winding. I don't know what 4002 pickups measure at, but there are a lot of RIC pickups that are in the 7k to 15k range depending on the type...

[Kopfjaeger]

CJ,

Thanks, I'll have to re do the measurement since I was fumbling with it at 0500hrs this morning!! I'll pay more attention to what scale the meter is in. I was having dreams all night of measuring it and coming up with all sorts of screwed up numbers, seriously. What the heck is wrong with me!! Obliviously I was thinking way too much about it!! I had to measure it moment after the alarm clock woke me or I'd be obsessing over it while getting ready for work. Yeah, that's just the way my mind works sometimes. Drives me nuts sometimes, if I let it.

As for the schematic Jeff, yes, a friend sent it to me.

Sepp

[cjj]

When you do, please post the results here. I'm compiling a table of specs and such on RIC pickups.

Even better, if you ever are at a point where you have the pickups out of the bass and will have them out for a while (like when doing a refin), I'd love to make a full set of measurements on them (inductance, series resistance, parallel capacitance at several frequencies using my HP4263A LCR meter)...

[Kopfjaeger]

CJ,

Some of the solder points look like bird **** so I imagine they will need to be redone. I have someone in mind for the restoration, if he will take her on. If he has to pull her apart then I'll see if I can have him send them to you for a full inspection. Anything that helps the RIC community.

As it is I'm looking at a new ebony fretboard $$$, body/neck separation, and possible neck separation that all need to be re mediated. My mind is wandering at how that needs to be addresses and the course of action to fix it. This may look like an autopsy before it starts to look good!!

Sepp

[coolingitdown]

It's going to be really cool when it's done, though! Can't wait to see this project finished!