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Messages - OZDOC

#1
This sort of issue is almost impossible to help someone with by remote control.
It's easy enough to make suggestions and encouraging comments, but it's never clear whether the solution would be self-evident if you could actually lay your hands on the instrument.
For example, have you remembered to put the aluminium shield back over the reed bars?
I would avoid going down the path of adding things to the instrument like shielding until you have it working the way you remember it.
It's highly likely that it is just a single shielding connection that has mechanically broken while you've been working (or one that has not been resoldered to the amp pcb).
There is a huge double spread picture of the insides of a Wurlitzer 200A (with aluminium shield removed) in Classic Keys: Keyboard Sounds That Launched Rock Music that could help you track down missing or unusual wiring.
See attached thumbnail of the picture.
David
#2
Yes, I'm leaning the same way as Agarcia. What I'm wondering is - are you particularly close to a radio transmitter? If you took the Wurli to another location well away from your house, is the problem still there? You may be chasing something which is not a particular fault of your keyboard. I'm assuming that you've never had a working Wurli in the location you're currently at? It would be good to prove that the problem exists within the unit before tearing your hair out trying to solve it.
#3
Sounds like you're on the right track.
Examine the assembly of the amplifier to the chassis and all the wiring loom connection points.
Put a red mark on the schematic where you identify a path to ground and check whether that connection exists in the original schematic.
Make sure that the principal path to ground through the power supply is actually continuous.

Another thought is: Did you use shielded cable for the signal connections from the reeds to the amplifier?
Have you simply got a missing shield connection?

David
#4
Did you take pictures of the wiring before you disassembled things?
Where have you made earth connections that were not present before you disassembled?
David
#5
Speaking from Australia where we have 240V 50Hz power, I own many US voltage instruments which I run from step-down transformers (variously marked 240 to 120, 220 to 110, 240 to 115). All my transformers have been bought from hobbyist electronics stores (Jaycar in Australia) rather than, say, travel stores or on-line. I have never had a problem with failure or out-of-spec performance. Mechanical transformers eliminate the possibility of electronic noise being introduced by a poorly filtered step-mode electronic power supply - the downside is that these are heavy and bulky and often are capable of delivering far more current than needed. But I also have some very small step-mode supplies which have been chosen to be well matched in terms of current draw and which work perfectly with no noise. With some US instruments I replace the main power transformer in the keyboard with one that has a 240V primary winding. It is my understanding that this will not be a simple option in the Wurlitzer as the secondary side has multiple taps. However, export models of the Wurlitzer were made, so somewhere out there you may find the right transformer to permanently modify your instrument. With the Wurlitzer, frequency is not an issue - UK 50Hz is OK. Unlike my Hammond B-3 (pictured in Classic Keys) that requires both voltage and frequency conversion to operate at the correct pitch.
David
#6
That certainly is a weird component geometry.
Perhaps someone forgot to include the resistor in the board layout and it was too late to remake it?
What they appear to have done is use a capacitor with axial leads and add the resistor in series with it to use the holes provided for a capacitor with radial leads.
You can use a radial lead capacitor to replace this daisy chain of parts but it may be advisable to sleeve the various leads with heatshrink tube to avoid shorts.
David
#7

Here in Adelaide my starting point is usually a leather and saddlery supplier like this:
http://www.adelaideleather.com.au/index.php?main_page=index&cPath=24_26

David
#8
The chap that has been conscientiously working on this Wiki page (Ritchie333) recently upgraded it with reference to the latest research in Classic Keys. So, as Wiki pages go, it's pretty good.
David
#9
Buying / Re: Rhodes mk1 suitcase
August 27, 2020, 08:28:09 PM
Hi Shane
There is a reasonable supply of Rhodes pianos in Australia but they seem to change hands infrequently. And often they find their new owner without advertising. You could try ringing the keyboard salespersons in all of Melbourne's instrument shops. These guys often have lots of band contacts and may know of a potential seller. Otherwise it is a matter of keeping "saved searches' going on Ebay and Gumtree.
Importing one from the US may get you there more quickly if price is not a significant problem. The Australian exchange rate with the US dollar and shipping difficulties during Covid make this much more expensive than it has been. The businesses in the US that regularly sell internationally will often have the shipping contacts to reduce shipping cost and difficulty, but they are likely to charge top dollar for their keyboards. A good Rhodes bought in the US really shouldn't be more than $US1000 - but these days the shipping (air freight) may add $US2000.
David
#10
If you can't tune it low enough you're going to need another piece of spring weight to increase the tip mass of the tine.
If the note doesn't sound like the few near it, check to see whether the tip of the tine is positioned at the same height and distance relative to the pickup nose.
David
#11
The Fender Rhodes Electric Piano / Re: Voicing
July 17, 2020, 01:39:19 AM
I guess there are a few extra questions:
Is this tine at the break-point between hammer hardnesses? That might make it appear different by contrast.
Is the tine obviously from a different batch - colour of plating and other physical clues.
Usually lifting the tine tip above the pick-up nose makes some difference. Do you hear any difference?
You could try shortening it very slightly and using a slightly heavier spring weight.

Then move on to tine swapping until you find one that fits in.
David
#12
Hi, the CP-70B is my favourite classic keyboard. Given that it is based on a conventional piano action the same warnings apply that would apply to buying a 40-year-old piano. If the action has been heavily used or abused the work required to make it worth owning could be extensive. If the piano no longer holds its tuning, walk away. In general, you are better off waiting for a lightly played, lightly gigged instrument. David
#13
In case no one else is noticing, great work Steveo. Above and beyond the call of duty.
#14
Hi James - welcome to the forum. Just letting you know that your request is being noticed and, hopefully, one of the piano tuners on the forum will kick in with useful information soon. David
#15
Hi Charley
This sort of instrument is very prone to noises caused by dust contamination between the reed and the common plate.
I think your plan of doing a thorough clean is the right place to start.
Sometimes sliding a small piece of bond paper into the reed gap can be used to clean grit from a gap.
#16
Well, well, well :)
Have you had that in your diary all this time?
I wonder whether you'll get an update on progress?
David
#17
It is possible that the tine itself is not firmly seated in the mounting block. Any looseness in this sleeve fit will destroy the tine's ability to ring.
#18
My rule of thumb is, if it's rare, treat it with more respect.
I also tend to apply this rule to instruments that have survived forty-odd years in near perfect condition.
Most models of Rhodes pianos are plentiful, so you're not destroying the integrity of one of the few remaining samples.
But ultimately, all keyboards are intended as performance tools, so making it functional usually outweighs preservation of its integrity.
It's interesting to note that after many decades elapse, even the non-authentic modifications of instruments take on historic significance.
In the 1700s many harpsichords were converted to pianofortes, and no museum or collector today would consider undoing those modifications.
David
#19
There are some actual piano tuners on this list who may chip in with more useful information.
My understanding is that this will be to do with the action back check.
Here's a video talking about it. https://www.howardpianoindustries.com/adjusting-the-backcheck-distance-on-a-grand-piano/
But your issue may not be an adjustment issue, it may be a materials wear issue. For example felts may have worn too smooth.
Look closely at the action of two adjacent notes in your piano - one that is checking properly and one that is bouncing - to see if you can see obvious differences in the setup distances, back check angle, and wear of things like the felt surfaces.
#20
Who can argue with that? :)
The Mk I is a class act.
Very elegant.
#21
I can't give you a tech's answer - and hopefully one will be along shortly to help you.
But it seems to me to be a natural consequence of the way the pickups are daisy-chained together (see attached photo).
Check the Rhodes service manual to see whether this pattern of chaining is consistent from instrument to instrument or somewhat random.
David
#22
The Wurlitzer Electric Piano / Re: Hum Shield Tips?
March 31, 2020, 12:15:31 AM
If vibration between the top of the shield and the underside of the lid is you problem then half inch wide self adhesive expanded polyurethane foam tape is one solution. This is normally sold in hardware stores as a DIY method of stopping drafts around doors.
#23
Ideally you'll resolder the eyelet back - or get a replacement one that can be crimped onto the wire.
Yes, you can temporarily strip the wire and wrap it around the screw.
You should be able to hear what, if any, effect the loss of this particular ground point has in your particular environment by simply touching the bare wire to the screw and listening for any difference.
David
#24
At the risk of promoting my own book, Alan Lenhoff, one of the authors of Classic Keys: Keyboard Sounds That Launched Rock Music, interviewed several of the knowledgeable techs in the US about this and discussed the issue of best Rhodes models in the Rhodes Piano chapter of that book. Opinions vary widely, and the answer is often related to the style of music you are playing. I have a superb early '80s MkII Suitcacse which is wonderfully playable - but so too is my mid-'70s MkI. I know that Alan prefers an early '70s Mk I.
#25
Thanks for the plug Alan.
I went looking to see whether Wurlitzer documented the ohmage of the headphones they expected to use - and couldn't find a reference.
It was the era of 8 ohm headphones - so this might be the expectation - but there is 470 ohms in circuit to significantly cut back the voltage anyway.
So perhaps this is just a voltage overload issue with your new phones rather than an impedance issue?
Did you try turning the Wurlitzer volume knob right down?
How well did your old headphones work?

It might be fun to track down an actual pair of 1970s Wurlitzer branded mono phones.
#26
There have been other posts exploring what you are questioning - for example:

https://ep-forum.com/smf/index.php?topic=7024.0

Try Googling things like "EP-Forum wurlitzer headphone impedance."

I suspect that the impedance of your headphones differs from what was intended in the Wurlitzer.
As mentioned briefly in the above post, there are all sorts of little adapter boxes available in the audio industry for impedance matching, isolating, and noise.
These can solve problems when two circuits don't play well together.

Check out Palmer Audio Tools (things like the PLI-01 Line Isolation Box) and Radial Engineering (things like their ReAmp transformer isolater)
#27
Never had a need to do it - but perhaps something like a custom throttle cable will provide a solution?
http://www.controlcables.com/throttle-cables/
#28
I've not tried those mods. As you'd be aware, you can temporarily pop those capacitors in the circuit using alligator clips and decide whether you (or your customer) like the results. And you can explore variations of the values. But it seems to me that, if it's hiss rather than brightness that you're chasing, then thinking about low-noise transistor substitutes might be worth experimenting with.
#29
I don't have the perfect photo on my computer, but the one attached suggests that what you are looking for is looseness between the two sides of this yoke that lifts the two halves of the damper mechanism. Check the fasteners associated with holding the two sides of this mechanism together. both sides should move in concert. Check that the pivots at the extreme ends of the two halves of the damper mechanism are in place and have no slop.
#30
Good demo videos. However, while this is demonstrating the problem, we can't see enough detail to understand why the bass section of the dampers are behaving differently to the mids and uppers. Unfortunately I'm currently in a location where I can't get to my 200A to see what might be loose or broken to produce the effect you're showing. Some video of the audience side of the mechanism may reveal the problem. Steveo - do you have a 200A handy that you can examine to see why one half of the damper mechanism may de-couple from the other?
#31
If you take the cover off the upper mechanism (see photos in Classic Keys - pages 101 to 104) you will find that the dampers are individually adjustable for every note.
But first check that the pedal connection to the underside of the keyboard has not been tightened down too far - pulling all the dampers too close to their reeds.

The top 5 notes on a Wurli are intentionally undamped - see photo Classic Keys pages 103 and 104.

I'd check the attachment adjustment of the pedal at the underside of the keyboard to ensure that the pedal is not drawing the dampers down too soon.
#32
It's possible that there was a loose or weakened wire attachment to the amplifier that finally failed with your minimal disturbance.
Trace the wire back from the audio ourput and the speakers to see if you can see a mechanical problem.
#33
Other Keyboards & Software Synths / Re: Whammy bar
December 19, 2019, 07:55:32 PM
As far as I know, the E7 harp assembly is the same as in a D6 - so the whammy bar should work. The photos that I can find of the inside of the case suggest that it has the same sort of room as in a D6.
#34
Other Keyboards & Software Synths / Re: Whammy bar
December 18, 2019, 05:50:18 PM
Best to contact Ken directly and ask.

David
#35
The Wurlitzer Electric Piano / Re: Chemical fluids
November 27, 2019, 09:26:08 PM

Naphtha is a petro-chemical solvent. So other solvents would be suitable as substitutes - test to see what happens.
It is apparently being used to dilute the silicone.

Silicone oil is available in all sorts of viscosities from hobby shops that deal in radio controlled cars.
Perhaps you can buy one that is already thin enough?

But perhaps you can get the correct lubricant from a European piano parts supplier such as KD Piano Parts? Or even your local piano tuner?
https://kdpianoparts.com/shop/58-polishes---lubricant---cloths------/
#36

Both speakers see the same mono output from the amp - so that suggests the problem is associated with the speaker - or the wiring to the speaker.
Have you checked and reflowed the solder joints to this speaker?
Have you gently jiggled the wires to see if something is not firmly connected?
Can you easily remove the speaker to see that the cone is not damaged?
And that there is no dirt trapped against the cone.

It is also possible that the distortion relates to either the cone sagging on its suspension so that the voice coil drags in the gap, or the frame of the speaker being slightly distorted by uneven tightening of the four screws, which also can cause the voice coil to drag on the gap. Opening and closing the lid of the unit while you work on it may be producing the variability you're observing. It's possible that distortion of the frame can be fixed by loosening off the speaker and carefully re-tightening it. If it's sag from aging, you may get temporary relief by rotating the speaker 180 degrees when you replace it.
#37
Going back through the things you seem to have eliminated:
1/ The signal from the harp (this is identical to the signal out on the name-rail) is clean.
So it is not the harp picking up radiated noise.
2/ The main Rhodes amplifier, separated from the Rhodes name-rail preamp, is clean and can amplify cleanly a signal from some other device.
So the power-amp is not faulty.
3/ This leaves the pre-amp circuitry in the name-rail pre-amp. The noise you are hearing is apparently being pulsed or modulated by the vibrato part of the pre-amp circuit.
So somewhere along the amplification chain in this pre-amp is a faulty device.
Examining the signal of a single note on an oscilloscope as it is passed from transistor to transistor should track down where the noise initiates.
If the noise is equally on the right and left channels of the stereo reverb then it should be in the mono section prior to this.
If the noise is only on one of the stereo outputs then that also narrows it down.

If the problem is isolated to the name-rail pre-amp, then this is the only part of the keyboard that you need to deliver to an electronics workshop to have this problem solved.
#38
The Wurlitzer Electric Piano / Re: Upper Register Sustain
November 12, 2019, 05:37:32 PM
Good question. I've never needed to try any of the suggestions I've made above. I would think that the downward force on the fastener head would need to be so great to ensure good resonance of the reed that the electrical connection would be certain.  David
#39
The Wurlitzer Electric Piano / Re: Aux Wires on 200 Amp
November 10, 2019, 10:07:10 PM
The white plastic coated wire is the signal, and the silver braided shield wire is the ground.
The twisted together shield wire is typical - and not a problem provided no stray strands short to some other device.
The signal on this wire is actually an AC audio signal so you may not have any ill effects if it is wired around the wrong way.
#40
The Wurlitzer Electric Piano / Re: Aux Wires on 200 Amp
November 10, 2019, 05:14:40 PM
If wired correctly the braided sheath wire should be the ground.
#41
The Wurlitzer Electric Piano / Re: Upper Register Sustain
November 10, 2019, 05:13:10 PM
All is not lost.
The excellent sustain of these notes indicates that they are good reeds with excellent coupling to the mounting chassis.
There are a couple of things you can try - however, I've never tried them, so report back to the forum if you do.
The easiest would be to get a lump of Blu-Tac or chewing gum and stick it on the base of the reed a little out from the screw. The theory is to provide a small amount of damping permanently to the reed without significantly altering the reed weight.
Another possibility is to get some thick felt and cut a strip that you can lay across the bases of the last 5 reeds. You may need to tape this in place and weight it slightly.
A more difficult experiment would be to take the reed out and put a very thin shim of bond paper between it and the chassis. This may get you to a point where the coupling to the chassis is sufficiently impaired that the note has a shorter ring. But getting the reed back correctly aligned in the pickup and placed so it is still in tune could be a challenge.
David
#42
The Wurlitzer Electric Piano / Re: Upper Register Sustain
November 09, 2019, 07:33:29 PM

The last 5 notes have no dampers. So altering the screws will not alter the sustain. These 5 notes are intended to sustain - the duration of sustain on these notes is generally fairly short.
In some reed and tine pianos the makers add extra mass to the mounts or resonators of these upper notes in order to get the sustain up to an acceptable level.
David
#43
The Fender Rhodes Electric Piano / Re: Buying advice
November 02, 2019, 10:01:09 PM
Check to see if the felt dampers that sit underneath the tines are actually making contact with the tines when a note is released. You may need to adjust the position of these or, if they are too worn, replace them.
The general advice with Rhodes pianos is that everything can be fixed. As long as the instrument is basically sound, and is not mildewy, or badly water damaged then you can progressively restore and set up the instrument to play the way you like it. Harold Rhodes himself encouraged players to adjust and perfect their own instruments. There are plenty of second hand parts available, so buy it and start enjoying it.
#44
Yes, you're correct.

You can experiment with how far above the Wurli the Clav needs to be for the buzz to be acceptable.
Then buy a stand that holds it above the Clav at that distance.
You can make sure the Wurli is disconnected from power when you play the Clav.

You can also experiment with an earthed metal plate between the two, or an earthed box around the transformer in the Wurli.
(Remember, in the latter case, you're dealing with mains voltage.)
It may also be possible to have the Wurli transformer changed for a toroid style one that radiates less magnetic field.

Another solution that some use is to place the Clav above another electrically passive instrument such as a Stage Rhodes.
#45
Hi Chris, while I don't have my circuits for this here at the office, if you're able to get a clean signal from the accessory insert point, that suggests that it's not RF. The sort of noise you're hearing is much more likely to be a failing or loose component in the pre-amp or main amplifier. The noise you're hearing has a cyclic nature - something charging and discharging. Perhaps to do with the vibrato circuit. If it's a failing component it may be a capacitor. However, it could be a loose or failing component (like a valve or transistor) that is simply creating noise pulsed by the vibrato circuit.

This is going to be unrelated to the work that your previous tech has done - and possibly something that vibrated free during transport. There should be a local home organ repairer near you who makes house calls who can solve this problem quite quickly. It will almost certainly be a generic amplification problem and not a Rhodes specific problem.
#46
Not at home with my piano at the moment - but... The method you should use is to get some not too stretchy cord and fasten it between the front legs and the pedal attachment points.
You do this with the pedal positioned in the position comfortable for your playing position, and adjust until it feels right. The push rod should be reasonably vertical but can be at a slight angle to accommodate your leg length and seat position. You now have the perfect measurement for your chain lengths. If you don't have the attachment fittings for the chains to the front legs you can just use cable ties.

David
#47
My Cembalet restoration got put on hold while Alan and I completed the book on vintage keyboards we were writing - see Classic Keys, Lenhoff & Robertson on Amazon Books.
There are a few photos of my earliest Cembalet in that. But, with your experience in mind I think I'll set aside the felt dampers that I was going to fit to it, and find a suitable foam extrusion. There is no doubt that the felt has the ability to retain charge - which is always a point of concern with capacitive pick-up systems.
#48
I think you're on to something about the felt dampers. The originals were urethane foam I think.
It is quite possible that the felt is inducing a static charge on the reed.
The Pianet suffered from similar problems when the original leather and urethane pads were substituted for solid silicone pads.
#49
The first thing that comes to mind is a faulty capacitor - but you say they've all been changed.
So, possibly some dust bridging a reed/pickup gap? Run a slip of 80gsm bond paper through the gap between reed and pickup.
#50
Here are some things that have worked for international shipping.
Double wall cardboard is fine - but I always use bubble wrap and styrene foam layers.
I always try and make sure that the pack is a two person lift - so that a single guy doesn't keep dumping it on its end.
I try and make sure small forklift standoffs are included so forklift tines aren't punched into the keyboard.
David