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Hi :-)

Safest way is to leave the Piano and amp grounded and use a Line-iso-box for the audio connection. This way, both grounds keep sepatated.  Palmer 'Wupper' or Radial 'StageBug' will do.


Jenzz

Hi :-)

What happens when the amp is disconnected?

On a Wurlitzer, signal ground is connected to earth. On most guitar amps, its the same. As a result, both grounds are connected via the earth wire.

If you plug the Wurlitzer into the amp via audio cable, the shield inside the cable will close the ground loop, causing probably hum.


Jenzz

Hi :-)

Is the Piano connected to any other gear / Amp?

There sometimes connections that will form an internal ground loop. Avoid the connection on the right end between the chassis plate and the harp. This connection is already established by the shields of the wire harenss going to the preamp PCB on the harp.

Jenzz

Hi :-)

The drawings are right, this is the way its supposed to be.

You should have 3 different sort of springs:
Stiff (mostly marked with yellow spray paint) on both tonebar screws for the bass range
Medium (plain) on both tonebars in the midrange up to the right harp bracket and 'pickup-side' of the treble tonebars
soft (mostly marked with blue spraypaint) for the 'Keyboard-side' of the treble tonebars.

In some cases, the first 4 tonebars right from the right harp bracked will have medium springs on BOTH screws. The intend seems to be because these 4 tones use the somewhat softer white hammertips.

The average distance between the bottom of the tonebar and the wood of the harp should be 9,5mm (= thickness of the square tine bolt). Looking at the pic, most of them seem to be too low.

Jenzz

Hi :-)

All of these transistors will work (watch for different pinout!), but since this is the first stage, a low noise typ should be the choice. I would recommend MPSA18 or 2SC1845 for the first stage (again, watch out for different pinout)....


Jenzz

Hi :-)

Since the input buffer (T1) stage draws no significant current (not voltage drop accross R12), i think T1 will be damaged.

I would also recommend the change C11 (filter) and C6 (feedback). Electrolytic caps of this age are prone to high leakage, loosing capacity or being shorted.

Jenzz

Hi :-)

Did you check the cable from the RCA jack going to the pickup system? What about the voltage directly at the pickup electrode? Remember that there is an additional 10Meg in series, so voltage reading will only roundabout 70 V.

Since you have a good signal when plugging into the phono: Do you obtain the marked 12V at the collector of T1 ?


Jenzz

Just took some voltage readings.  I'm getting 150V where I should be getting 180 (on the other side of R1).

Any ideas on how to fix this are greatly appreciated.

Thanks!

Hi :-)

This is quite normal. Keep in mind that the 180V voltage is fed via a 2M2 (42) resistor into the last cap (44).

If you connect a multimeter, the input resistance of the multimeter (10Meg in most cases) will form a voltage divider with this 2M2. The result will be a roundabout 150V reading at C44.

Jenzz

Hi :-)

Since your Suitcase is from 1980, chances are that you have the preamp version that produces some kind of 'faint tremolo' even when tremolo is switches off.

In the former preamp version, the switch disconnects the LEDs in the photocouplers from the oscillator and cuts off the LED at the panel.

In the 2nd version (like yours), the switch only cuts off the 'intensity' pot and the LED on the panel, but the  photocoupler LEDS are still runing. Due to the circuit itself, this will produce a faint tremolo, which is more prominent over headphone than the cabinet (hence that both speaker channels work in the same box).

Jenzz

Hi + Welcome :-)

The pickups with the white band are prone to failiure. The laquer on the copper wire gets / is broken at the sharp edge of the bobbin (green circle in attached pic)). Due to the broken covering, the copper gets corroded and the wire is broken.

Since on a 54 all pickups are in series, even a single dead pickup will have the whole instrument dead.

The only solution will be to replace or rewind the dead pickups. The keep (hopefully) the working pickups intact, place a drop of urethane laquer at the area at the circle to recover the laquer layer on the wire.

Jenzz

Jenzz

Hi :-)

Yes, this would help. But i would only change up from B1 (the hard blacks and the wood core tips in the treble range), not the whole instrument.

Jenzz

Hi + Welcome !

Since the Hammertips are harder in the upper range (there a 5 grades of hardness on a Rhodes), this is pretty normal.  Due to ageing and playing, the hammertips develop a flat spot on their striking edge, making them even harder.

This is most pronounced at the yellow / black transition (A# 1 to B 1), as shown in your video.


Jenzz

Hi :-)

The switches need cleaning. If all tone switches are off, the instrument should be silent.

Jenzz

Hi :-)

What about the cable you're unsing from the cabinet to the piano? Is it 4 wires + shield? Be aware that the shield should only be attached to the connector housing of the cabinet side, piano side should be open. Otherwise you get a ground loop.

Inside the cabinet, tie the chinch cable together and keep them as far away from the transformer as possible.


Jenzz

Hi :-)

The upper range is sensitive to striking line (take a look at the manuals, the glued hammer stems could have moved over the years, resulting in impropper striking line) and hammer hardness.

The felt covering of the hammers at the upper range is thin to get the neccesary hardness. The felt covering often has cracks and got puffed, so the hitting surface is too large and the hammer has become too soft to build up the enery. As a result, these notes are much quieter.

Re adjust striking line by applying heat to the glue of the hammer stem and move back or forth. This is try and error. There will be a position where the reed will respond best.

Jenzz

Hi :-)

Since it is an Mk2 and from '81, chances are that your piano frame was mounted into a case that was supposed to be for a plastic key Mk2.

The lip of the lower part of Mk2 cases for the plastic key models is roundabout 1 cm lower than on a case for wooden key Mk2.

So, if you mount (for some reason) a wooden key piano frame into such a case, you will have a space between lip and keys.

Jenzz

Hi :-)

Do you have both + / - 30 V from the power amp power supply (the 2 big caps)?

Check or replace the 1uF cap (C2) across the offset pot. If it fails / shorted, the output is totally out of DC balance and full supply voltage can be seen at the output. Had this issue on some Suitcase Amps in the past....


Jenzz

Hi :-)

I can't hear any undertones, just the normal intermodulation that you get when playing certain intervals (which is normal on a Rhodes).

Is this a miked sound from an amp?


Jenzz

Great review, thx!

Jenzz

Hi :-)

The additional cap is original on an 88 piano. It forms a high-pass for the last upper 12 notes.

Do all of the upper 12 pickups work?

You cannot view this attachment.


Jens

Any transformers nearby?

Remember that the aliminum foil will only shield against static / capacitive coupling, but not against magnetics...

Jens

Hi :-)

Did you plug directly from the harp RCA, while having all other connetions (preamp) disconnected?


regards, Jens .-)

Hi + welcome :-)

Give it a try to connect the damper bar to harp ground. The damper bar is electrically floating, since the axles are running in those nylon bushings. All noises that the bar recieves are then capacitive coupled into the pickups, which are right above, esp. on the bass side.

The older models had such a connection right off the factory...


Jenzz

Hi :-)

Remember that you will allways need some force to lift up the damper arm. The damper arm is spring-loaded, so maybe you could reduce the tension there a bit. The drawback of this is that the damping itself will be not that instand / accurate as before.

Jenzz

Hi :-)

There are some interresting pics from the inside Mk8 at NAMM on the german 'Musikerboard'...


https://www.musiker-board.de/threads/namm-2023-the-transition.740533/post-9502871



Jenzz

Hi :-)

You have to cut the sustain dovel down to lenghts of that of a stage piano, then insert this guide cup:

https://www.vintagevibe.com/products/fender-rhodes-sustain-guide-cup


Now you can use the normal stage pedal...


A hotfix will be to drill a hole to the bottom of the dovel to fit the size of the pushrod.



Jenzz

Hi :-)

VV felts are harder / more compressed than the originals, you did nothing wrong....

Jenzz

Hi .-)

Looking at the pics, it seems that the leads of the diodes have melt into the housing of silver caps, probably touching the inside foil?

Jenzz

Why not using the old / original screws?


Are they the thick ones (4,2mm) or the thin ones (3,45mm) diameter below the head?


Jenzz

Hi :-)

You should change these fuses to the standard 5x20mm + holder. You can use 1,6A (which is the nearest type in EU) slow-blo. Since the voltages are not high, voltage rating doesn't matter here.

Jenzz

.... i figured it sounded very much like my behringer vp which is a clone of the small stone, really need to buy the real deal at some point,

Hi :-)

I would give the VP an try...

Look for the the Moot Booxle video on YT where he compares the VP and a V3 Small Stone. I think the VP sounds 'spot on'.

Jenzz

Hi :-)

Sounds pretty much like a vintage EHX Small Stone Phaser with color switch in 'Up'-Position... And some volume tweaking...

Jenzz

Hi :-)

This problem in very common. You need a Line-Iso-Box.

The Wurlitzer's signal ground is tied to the pianos earth connection (3-prong connector).
Mostly all tube amps do the same, signal ground is tied to earth (for saftey reasons / High-Voltage).

If you connect a Wurlitzer to a tube amp, you will close the ground loop via the shield of the audio cable.

So, you need someting to 'isolate' the signal path's ground. This can be done by a line iso-box (1:1 audio transformer)... Palmer PLI-01, PLI-05

Jenzz

Hi :-)

The diodes have to handle the current of the power amp, so i would recommend something like the 1N5401 - 1N5407.

Jenzz

Hi + welcome :-)

Keep two things in mind:

The 5 hignest notes have no dampers, so there will always be some kind of 'faint ringing' when notes are struck.

When the pedal is released, all reeds are bend a bit downwards due to the tension of the sustain / damper arm mechanism. When you hit the pedal hard, the releasing damper felts will pull away from the reeds, causing them to ring because of their own bending tension.

The, this phenomenon is kind of normal to some degree.

Do you have a sound file?

Jenzz .-)

Pre-tuned doesn't mean 'exact'.

This is why i allways sale pre-tuned reeds a bit too low.

The machining seems to be more precise on the older models up to the 200... The worst machining is on the german models 201 / 300... It seems to me that the B-Stock parts were sent over here ;-)

It's the experience from over the years and what i see / measured here in the workshop... Maybe different from yours.


regards, Jenzz

Hi :-)

This is common due to the age of the piano. The pedestal felts and/or the key rest felt will be compressed to some degree over +45 years. I personally would leave this as it is...

The miracle mod doesn't adress this issue, it changes more of the overall feel of the action.



Jenzz

It would appear my balance rail is tilted back quite a few degrees. I'm not sure what to do about that. Any help would be greatly appreciated.

Hi :-)

This is pretty normal and the way its supposed to be.

See this pic from the manual:

You cannot view this attachment.

Jenzz

Another German related subject I'd like to discuss, is about those, almost original, T/M/Duo pads Mr. Werner Bothe was producing, but not anymore. I'd like, for future reference, to be able to produce/get my owns too as i have easy access to labs and small factories with CNCs, Laser cutters/3d printers,plastic molding machines etc. Seems it's a kind of silicone rubber square profile but i guess special attention and experiment is required to find the exact one with appropriate similar sticky properties.
 

Hi :-)

The pads fron Werner Bothe (he is just 30km from me) were made of the original casting compund. But for some reason, he made the pads bigger than the originals (more depth).

This causes them to stick not as good as the originals because of the slight bending of the reed, so they won't touch the reed at the same pressure with their entire surface.

Jenzz

Hi .-)

Since the treble reeds are very stiff, chances are that the hammer levers are bend in that area. The material is relatively soft to allow bending / adjustment.

BTW: I remmoned a re-cap job on the wholw instrument. Esp. the 'golden' Siemens caps are prone to leakage after nearly +45 years. Also keep in mind that the power amp chips are very hard to find.

(...last Pianet M i had in for service had a blown power amp chip + the speaker was fried due to a defective cap)

Jenzz

Hi :-)

Did you check this with dampers or with dampers complete off?

Since there are 32 reeds on every aluminum cast, there is always a chance that there are some reeds in harmonical conjuction with the 'main' note (octaves, quarts, fifths), swinging out-of-phase with all dampers off. This will remove energy from the 'main' note and shortens sustain, too.

Reed screw... Be sure that it is thight to a certain amount, not just snug. Otherwise the spring-action of the washer will not work as supposed. This can reduce sustain.


Jenzz

The new Roland JC-40 has a complete stereo signal path...

Jenzz

Roland JC 120H

Jenzz

Hi :-)

The Dyno filter has a kind of two-way signal path. 'Normal' mixes the unaffected signal to the output.

The other path runs into a fixed mid-cut, then into a passive Fender-style Bass/Treble network. Because of this, the volume can got to 0 when kompletely turned CCW. Anonthe buffer takes the signal to the output mix.

The stereo tremolo might give some impression of pitch shift / vibrato, because the signal source 'moves' in the stereo field.

Jenzz

Hi .-)

Keep in mind that the top e hammerflange is not part of a 12-piece hammer flange. To achieve the 73th note, this is a single flange with its own screw. Since this piece is cut from a former 12-piece flange, the securing pins at the bottom are only on one side. This will cause the flange to have a lot of side-play if the screw is not tight.

Jenzz

Hi .-)

As Peter suggests, the easy way will be to move the string.

The hard way is to loosen the PUs nuts, then they can be moved side-to-side slightly due to the oval / long hole. But then you have to be secure that there is no string over any of all gaps. For even results, check both lower and upper PU.

Jenzz

Hi .-)

Yes, i know that the edge is a machined part, but i have seen these tolerances here over 30 years. There are a lot of inaccurate machined casts out there...

Jenzz

Hi .-)

The idea is great, but doesn't work in real live, or is kind of 'random'.

After doing over 100 Wurlitzers, i can say: The distance from the reed-bolt thread inside the aluminum casting to the corner where the reed 'leaves' the supporting edge differs from cast to cast by roundabout +/-1,5mm.

So, tuning with another fixture than the 'real' cast (where the reed will be mounted to) will be only a approx. in tuning in most cases.

Jenzz

Hi:

Is it a 100W or a 80W Peterson model? Note that the Peterson preamp has a 5kHz lowpass filter in the signal path, so you won't get that much 'sparkle' anyway...

Do you have a sample of the actual sound?

Jenzz

Hi .-)

Is it a 73 or 88?

Are you checking directly from the harp or incl. preamp / cabinet?



Jenzz