'67 sparkle top pickup wiring configuration

[groover]

Hi guys,
Could someone please explain the wiring configuration on these old piano's? I've looked for a schematic but can't seem to find one. The wiring seems to cross over between every pickup. Except where the bottom 13 (which are upside down) join to the rest of the pickups it only has 1 wire joining. As you can see from my pic there's no 2nd wire joining the other bobbin, only the wire coming off the bottom bobbin continues the curcuit. Is this correct? It looks like the rest of the pickups are joined together in a criss-cross fashion with no breaks. Thats why i'm thinking that the upside down group of pickups should continue and be joined on both bobbins in the same fashion as the rest. And what difference does this method make compared to the later method of series-parallel. Maybe it has something to do with the impedance for the old amps the came with these pianos? I don't have the amp and was planning on just plugging directly from the harp for now. I think this should be ok to do?
Thanks for any advice guys 

[David Aubke]

I've always assumed they were trying to achieve hum cancellation by alternating the pickup poles. And that they finally decided it wasn't working or worth the extra effort so they adopted the current wiring layout.

I don't know how to explain the group that's in series. I'm not familiar with pianos of that age so I don't know if that's standard. I didn't even know those pickups had their wiring terminals on the underside.

[Ben Bove]

The lower notes on a sparkle top have the pickups turned upside down, due to the extra mass weights added at the bottom of the tonebars.  The weights could contact the poles and therefore short out the pickup signal, so for those notes they flipped the pickups.  You can see the location of the weights here:

[David Aubke]

The lower notes on a sparkle top have the pickups turned upside down, due to the extra mass weights added at the bottom of the tonebars.  The weights could contact the poles and therefore short out the pickup signal, so for those notes they flipped the pickups.

Did not know. Thanks.

Now, what can you tell me about that dowel that appears to be poking through the harp frame?

[Ben Bove]

Those dowels are factory, and I usually break them off!  My guess is some sort of guide for putting the harp back in place, I don't believe they had the harp side swivel brackets yet. 

[The Real MC]

Those dowels are factory, and I usually break them off!  My guess is some sort of guide for putting the harp back in place

Correct, so the strike point is maintained after tuning the tines.

I don't believe they had the harp side swivel brackets yet.

No they were not on my '67 piano.

[groover]

Thanks for all that guys. Yep there are no swivel brackets on this one either. I can see where someone has broken off the dowel pieces on mine too. I guess this is gonna make tuning and resetting the harp every time a bit more tedious.

So does anyone who has or has worked on one of these know if i am in fact missing a link wire between one of the bobbins connecting the reversed pickups to the rest? And would there be any benefit from rewiring the whole thing like my '81 mark2 is wired in series-parallel? Or should i leave wiring as it is?
Thanks so much

[Ben Bove]

I can't recall off hand and don't have easy access to my sparkle top, but I can only assume they should be connected?  Do you have any notes not playing?  Always worth a try jumping the posts and seeing if anything happens.

No need to rewire honestly, a lot more work than any real benefit.  These pickups rarely go out as compared to a later piano or Mark II.

[groover]

Thanks Ben.

I do have some pickups that don't work, or don't work properly. I have tried connecting those 2 pickups that we are discussing with a jumper as we think they should be and my results are quite strange. This is what i got:

When they're unconnected as per how i got the piano:

pickups 1-13 : work (upside down group), nice working clunk when tapped with screwdriver
pickups 14-49 : i get a soft tap when i tap with screwdriver  (check attached mp3 for the difference in working clunk and soft tap)
pickups 50-73 : work

When i connect the bobbin from 13 to 14 as discussed:

pickups 1-7 : work
pickups 8-32 : absolutely no sound when tapped with screwdriver
pickups 33-49 : soft tap same as without connecting wire
50-73 : work

Weird. Any suggestions? Anything i can try and bridge to see if i can bypass a problem pickup maybe? I'm thinking those quieter tapping pickups are dead and need to be fixed or replaced (please give me an opinion on this after listening to the mp3), but it seems really strange that some are completely dead and some still quiet when i connect that wire.
Thanks again

[Ben Bove]

If you get even a quiet signal out of each pickup, the good news is that they shouldn't be dead.  A dead pickup will yield no sound no matter what you try, so it may be more or less a wiring issue.

My first thought is that I would look at the pickups and connecting wires at the break points you noted (and neighboring pickups):

7&8, 13&14, 32&33, 49&50

Take a look for poor soldering repair, move around the joining pickup wires and see if any are broken or barely hanging on by connection.

I found the pickup wiring diagram from the service manual and sure enough it looks like the first 13 have a break at the check mark.  Check the other break points noted, I'm pretty sure you're dealing with braided wire breakage or poor repair of soldering.

[groover]

Ahhhh thanks Ben. I love hearing good news. Yep going by that diagram i found that there had indeed been some rewiring at some of the points where there is suppose to be breaks. I think someone before me has installed a couple of replacement pickups and then possibly joined all of these breaks thinking this is how it should be wired. I'm only half way through removing the tone bars and tines for cleaning up so i cant see the top end of the wiring as yet, but since the pickups work from 50 onwards i think from there it's probably ok. I'll let you know what happens when i correct the wiring as per the schematic.
Thanks for your help and advice

[groover]

YES!!! That was my problem. Someone had gone along and connected all the breaks in the wiring chain. Once i'd snipped them all they all work apart from 1 pickup. So i'll try and unwind  a bit of the pickup wire and re-solder it to the bobbin post. Otherwise i'll just buy a replacement one. Things are looking good for the restoration of this piano. Yay!!

[groover]

Actually i just realised i dont have the action parts for the first 2 notes, so if i can't fix the dead pickup can i just replace it with the first pickup which i'm not using and move the connecting jack wire to the 2nd pickup?

[Ben Bove]

Always great to hear a success story.

If you're looking for action parts on the first couple notes, you may have luck on ebay or I do know that Vintage Vibe has them in stock, http://www.vintagevibe.com/collections/fender-rhodes-parts-authentic-1960s-parts?variant=899450059

You may also find a pickup to work from that vintage.  I would leave the wiring the same, but you could swap out one of the pickups you're not using if you can't get the dead one alive.

[groover]

Hey Ben,
I tried cleaning the corrosion off the pickup rivets and i may have damaged one. But during that process i think i may have upset a join somewhere because i have replaced the 2 dead or damaged pickups with good ones and the noise (clunk) i get from tapping them all gets quieter from the bottom to the top of the piano. Do you know if i can test the resistance of the groups of 12 without having to cut any pickup wires to try and pinpoint what area of the piano the dodgy join is? And if so, what resistance should i get from a group of 12? I took my good pickups from the very first 2 in the piano which i'm not using, so the first group of pickups is only 5, not 7. That shouldn't matter should it? The wiring hasn't changed at all, just less pickups in the first group.   

[groover]

Disregard my previous post. I've realised that the wire connecting the earth had come off at the top end of the piano. Which makes sense why it got weaker the further up the pickups i went. I love when there's a simple solution...