Author Topic: Grounded 54 Rhodes - Pickups Dying One By One  (Read 190 times)

Offline mikecons

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Grounded 54 Rhodes - Pickups Dying One By One
« on: November 27, 2017, 11:11:38 PM »
Hi, guys!

Was wondering if anyone can help. My piano seems to be grounded, I have changed upwards of 12 pickups already and every time I do, I can play it for a bit then when I turn off the amp some time later and turn it on again, there's no sound. I do the pickup test with my screwdriver and that seems to short the piano back into action - there's sound again and I can play. But after a few times of doing that, a pickup will die - I locate, replace it then the same thing happens all over again: short into action, plays well, pickup dies.

I've replaced all my cables, tried different amps and even had our wall sockets reworked so there's no ground from those but still, the problem persists. Been reading through here but can't seem to find any similar issue - the closest seems to be the grounded/nasty/buzz discussions (http://ep-forum.com/smf/index.php?PHPSESSID=gmucnae6ujqotp76cnoaf6gj23&topic=6126.msg30701#msg30701). Thing is, there are no photos of 54s that I can refer to to see if my wiring is messed up.

Attaching photos here so you can see, perhaps you can see something I've missed?

Offline Tim Hodges

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Re: Grounded 54 Rhodes - Pickups Dying One By One
« Reply #1 on: November 29, 2017, 09:14:47 AM »
Hi Mike,

Strange that you should have that many go on the red coil pickups.

Out of curiosity have you tried by passing the preamp and instead taken the signal straight from the RCA jack on the harp to see if the problem persists?

My other thoughts are:

  • Break in the wiring
  • Tonebar touching the pickup wire
  • Preamp has some fault in the wiring and everytime you go near the piano you're connecting the loose connection again

Tim
Bristol Electric Piano Company
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United Kingdom

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Offline vanceinatlance

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Re: Grounded 54 Rhodes - Pickups Dying One By One
« Reply #2 on: November 29, 2017, 07:04:08 PM »
Maybe the coupling capacitor next to the output jack? Don't know the 54 so just guessing.

Offline vortmaxx

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Re: Grounded 54 Rhodes - Pickups Dying One By One
« Reply #3 on: November 30, 2017, 12:00:46 PM »
Out of curiosity have you tried by passing the preamp and instead taken the signal straight from the RCA jack on the harp to see if the problem persists?

I would definitely try this 1st. The volume and "tone" sliders are passive and don't really do anything but suck your tone anyway.

The pick-ups on a 54 are wired in series, so if 1 goes out, you lose everything. When I got my 54 I wanted to put a VV pre-amp in it. After reading here:
http://ep-forum.com/smf/index.php?topic=6665.msg33329#msg33329
and here:
http://www.shadetreekeys.com/2011/10/01/parallel-wiring/
and here:
http://www.shadetreekeys.com/2011/09/03/tine-bomb-preamp/
I decided to add some "jumpers" and reconfigure the wiring across the pick-ups to the "series-parallel" to accommodate the pre-amp, and to eliminate the problem of losing the whole piano when 1 pick-up goes out.

If your piano is still wired in series, I would try measuring the resistance across the whole pick-up rail. It should be around 10K ohms. If it is significantly lower, you probably have some dead or dying pick-ups. If not, then the problem probably lies somewhere else.
 

Offline pnoboy

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Re: Grounded 54 Rhodes - Pickups Dying One By One
« Reply #4 on: November 30, 2017, 06:12:17 PM »
  I don't know what your problem is, but it's not grounding.  Has anyone checked to be sure your amp isn't putting DC across your pickups?  It shouldn't be, but there could be a fault in it.

Offline mikecons

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Re: Grounded 54 Rhodes - Pickups Dying One By One
« Reply #5 on: December 01, 2017, 08:13:30 PM »
Thanks so much for all the suggestions, guys! Will try these out and report back!

Offline Ben Bove

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Re: Grounded 54 Rhodes - Pickups Dying One By One
« Reply #6 on: December 06, 2017, 01:47:03 PM »
These pickups appear to be the dark red color - a late 79 transition period before they started wrapping them in white tape, but they're the same faulty design.  They have the same deficiency of corroding at the terminals as those wrapped in white tape.  I had a late '79 piano with dark red wire pickups and clear tape, and had to replace a score of pickups.

Any 54-key model is in the Mark II period, but to confirm - if the TBJ number by your serial stamp is 017281-TBJ for the 54-key model, then it's the later, faulty pickup design. 

When you replace a dead pickup and the piano works but then dies again... the 54 is wired in series as mentioned above, they're like old christmas lights - one goes out and that's it.  If the piano is seeing a lot of use as of recently, the bad pickups might start showing up.  It can be a sad state of affairs for this generation if moisture or corrosion is present, but at least you've only got 54 and not 88 :) You might end up replacing anywhere from a handful to 20 or so pickups
« Last Edit: December 06, 2017, 03:41:28 PM by Ben Bove »
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