DCR vs. Rs

[kayakerca]

I have a '63 J-Bass bridge pickup. Customer says it's "weak" the DCR ~= 9.2kΩ, but the Rs ~= 15.8kΩ. I typically find that the impedance is about 5% - 6% greater than the DCR, but never like this. There are nor shorts between any of the rod magnets or either lead and each rod magnet. Would this indicate a short somewhere in the coil?

[David King]

Resolder the eyelets and see if anything changes. That 9.2kOhm seems a high for a 63 vintage unless it's hot out. Check the Gauss and see if you are hitting 1200-1350 on every magnet. Internal coil shorts would lower the DCR presumably, not raise it.

[kayakerca]

Resolder the eyelets and see if anything changes. That 9.2kOhm seems a high for a 63 vintage unless it's hot out. Check the Gauss and see if you are hitting 1200-1350 on every magnet. Internal coil shorts would lower the DCR presumably, not raise it.

Should have mentioned, I resoldered the eyelets. Actually I removed them and shortened them a bit to get to clean wire, tinned and reinstalled. The neck is in the upper 8k Range with Rs just marginally higher.

The magnets are fine running +/- 12,000. Interestingly the neck magnets are +/- 3,000 which explains why that one had very low output. Both were south up. I'm guessing that was still the standard of the day?

[David King]

I don't think so, I think they were always RPRW or equivalent.

[kayakerca]

I don't think so, I think they were always RPRW or equivalent.

Thanks David. I'll charge up the neck to North as the bridge is solid South as it sits. Looks like the bridge is going get a new wind of PE to the 9,000k + range as it is now.

[David King]

Look up all of Sam Lee Guy's posts for details on the P and J coils.

[kayakerca]

Look up all of Sam Lee Guy's posts for details on the P and J coils.

What is his username in the forum?

[Mike Sulzer]

I have a '63 J-Bass bridge pickup. Customer says it's "weak" the DCR ~= 9.2kΩ, but the Rs ~= 15.8kΩ. I typically find that the impedance is about 5% - 6% greater than the DCR, but never like this. There are nor shorts between any of the rod magnets or either lead and each rod magnet. Would this indicate a short somewhere in the coil?

What do you mean by Rs and how are you measuring it?

[kayakerca]

What do you mean by Rs and how are you measuring it?

Recording of the impedance reading of the '63 J Bass bridge pickup with my Extech LCR 200 meter.

[kayakerca]

Look up all of Sam Lee Guy's posts for details on the P and J coils.

Thanks David. Found his posts.

[Mike Sulzer]

Recording of the impedance reading of the '63 J Bass bridge pickup with my Extech LCR 200 meter.

So the high series loss indication might be from too low an impedance in parallel with the pickup. Any semi conductive alien life forms growing in 40 years of evolved beer spills?

[kayakerca]

So the high series loss indication might be from too low an impedance in parallel with the pickup. Any semi conductive alien life forms growing in 40 years of evolved beer spills?

Looks reasonably clean and tidy. I know the measurement difference indicates something, I was just hoping someone more technical might know what.

[David King]

That would be 53 years -same as me. I never tested my own self-impedance but I know it's pretty high and getting higher...

[kayakerca]

That would be 53 years -same as me. I never tested my own self-impedance but I know it's pretty high and getting higher...

So if I understand correctly, my self-impedance at my age of 60 should be so high that I can barely move! That explains a lot. :-)