? my 1972 4001 bridge pickup quit working

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Sir Ricardo
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? my 1972 4001 bridge pickup quit working

Post by Sir Ricardo »

?

I had not played my bass in a while, and when I plugged it in this pickup did not work.

Looks OK on the outside. Zero reading, however.

Thoughts on how to fix / revive / reanimate?

thanks much

Richard
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songdog
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Re: ? my 1972 4001 bridge pickup quit working

Post by songdog »

Does "zero reading" mean you measured a resistance of zero? Really zero, measured on a low-resistance setting of your meter? Examine the external wiring very closely with a magnifier, looking for anywhere it could be shorted.

I doubt that the pickup suddenly developed an internal short while the instrument sat in the case. I'd tend to suspect there was another problem like corrosion on the pickup selector switch (which would not be surprising if it wasn't used for a while), and the short you're now measuring happened when you unsoldered it to remove it.

Umm, you didn't try adjusting the pole pieces, did you? They look like they should be adjustable but they are not meant to be turned. They hold the pickup together, and the coil is wound over a little bit of electrical tape around the screws. Turn the screws and you wear through the tape and short (or break) the very fine coil wire. I learned this the hard way, several decades ago. :(
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Isaac
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Re: ? my 1972 4001 bridge pickup quit working

Post by Isaac »

I didn't know that, Bill. Good information.
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Sir Ricardo
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Re: ? my 1972 4001 bridge pickup quit working

Post by Sir Ricardo »

songdog wrote:Does "zero reading" mean you measured a resistance of zero? :(
Greetings Bill -

Thanks for the reply. What I mean is that it shows a reading of 1, and does not work.

I assume there is a broken wire somewhere?

On the underside of the pickup, the black lead is soldered to the extension lead, and there is a little bit of plastic sheath over the soldered area. Do you think it might be worthwhile cutting away the sheath, and seeing if the black wire is active? Perhaps the solder joint failed?

thanks

Richard
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songdog
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Re: ? my 1972 4001 bridge pickup quit working

Post by songdog »

Okay, is "a reading of 1" how your meter shows a resistance higher than it can measure? What scale is the meter set to? If it's set to measure (for example) 0-999 ohms, it will report an out of range condition, since the resistance should be around 8,000 ohms.

As I said in my previous post, I would be surprised if the pickup just stopped working while the bass was sitting unused. Before messing around with the pickup leads, I'd suggest being really certain you are testing it correctly, and look for the possibility of a different problem.
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Sir Ricardo
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Re: ? my 1972 4001 bridge pickup quit working

Post by Sir Ricardo »

Greetings Bill -

The pickup shows a reading of 1.

In contrast, another similar RIC pickup I have shows a reading of 6.58k ohms.

thanks

Richard
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jps
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Re: ? my 1972 4001 bridge pickup quit working

Post by jps »

Are you saying: 1 Ohm?
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Sir Ricardo
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Re: ? my 1972 4001 bridge pickup quit working

Post by Sir Ricardo »

.

Guys, my meter will register a 1 if the meter's leads are not touching anything. If the meter's leads are touching each other they will read a 0. If they are touching a healthy RIC bridge pickup's leads they read 6.58k ohms.

When I apply the meter's leads to the leads of the non-functional pickup in question, I get a 1.

.
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libratune
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Re: ? my 1972 4001 bridge pickup quit working

Post by libratune »

Are you touching your meter's leads to the PU wires? If so, I'd suggest taking the baseplate off and getting a reading directly from the PU hot lead terminal.
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Sir Ricardo
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Re: ? my 1972 4001 bridge pickup quit working

Post by Sir Ricardo »

libratune wrote:Are you touching your meter's leads to the PU wires? If so, I'd suggest taking the baseplate off and getting a reading directly from the PU hot lead terminal.
Yes, to the PU wires. I'll take off the baseplate and do as you suggest. Thanks for the suggestion.

:mrgreen:
prowla
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Re: ? my 1972 4001 bridge pickup quit working

Post by prowla »

You've got a couple of options if it truly doesn't work:

1. Get it fixed.
2. Put in a replacement pickup (I have an SD in my '72 Ric) and get it fixed anyway!
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Kopfjaeger
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Re: ? my 1972 4001 bridge pickup quit working

Post by Kopfjaeger »

Nice, A large magnet slotted pole pick up! I love the growl on those!! Send it out and get it rewound! A guy like Tom Brantley can do it very reasonably for you. He's in North Carolina and on Facebook. He's fixed a few of mine. Very knowledgeable and his work is awesome!

Sepp
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prowla
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Re: ? my 1972 4001 bridge pickup quit working

Post by prowla »

Kopfjaeger wrote:Nice, A large magnet slotted pole pick up! I love the growl on those!! Send it out and get it rewound! A guy like Tom Brantley can do it very reasonably for you. He's in North Carolina and on Facebook. He's fixed a few of mine. Very knowledgeable and his work is awesome!

Sepp
I think the workmanship on those is quite amusing; they just gouge a channel out of the magnet down to where the hole is in the base plate for the wires to go through.
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Sir Ricardo
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Re: ? my 1972 4001 bridge pickup quit working

Post by Sir Ricardo »

libratune wrote:Are you touching your meter's leads to the PU wires? If so, I'd suggest taking the baseplate off and getting a reading directly from the PU hot lead terminal.
Well, I just took the baseplate off, and all I see are 2 wires (one white, running into the heart of the pickup, and one black, running into the side of the pickup). See the photos attached to this post. I don't see a terminal.

The only terminal I see is the one that I originally saw, which is clearly visible on the back of the pickup, and is shown in my original post of several days ago.

So, Ron, I guess I don't quite follow you. Is the 'hot lead terminal' something other than the terminal that is clearly visible in my first photos? Because I already tried taking a reading from that terminal (which is attached to the white wire) and the end of the black lead. I got a '1'.

I'll look forward to hearing from you.

thanks

Richard
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prowla
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Re: ? my 1972 4001 bridge pickup quit working

Post by prowla »

One wire comes from where the coil starts in the centre of the pickup and the other is from where it ends out the outside edge after 1500 or so turns.

There are no terminals per-se, but the earth one is attached to the base of the PU assembly and also serves to hold things in place a bit.
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