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Messages - Jenzz

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Hi .-)

Seems a matter of string placement / pickup alignment... There are six magnets in each pickup. Be sure that:

Every magnet detects 10 strings. Avoid a string going over the gab between the magnets, it will be significant lower in volume.

Be sure that the gaps of the upper and lower pickup are aligned to each other. This can be done by loosening the pickups mounting screws. Otherwise, you will get the effect that you are describing....

regards, Jens .-)

The Fender Rhodes Electric Piano / Re: Strobe tuners
« on: July 12, 2017, 11:02:42 AM »
Here is what i use:

In the Workshop:

On Location:


Buying / Re: Vintage Electric Piano for Busking?
« on: July 02, 2017, 01:54:45 PM »
What about a Hohner Pianet T?

The only drawback might be that it has no sustain pedal...


Hi .-)

Don't care about exact 0V on T9, the more important thing is to have the proper voltage accross R 37 / 38. I allways set this  to 5-10 mV. The annoying thing about the PCB design is that T9 should be attached to directly to the heatsink for optimum thermal coupling, since it works somewhat as a 'temperature sensor' and therefore regulates the bias / idle current.

So, with T9 in its original Position, bias current is very sensitive due to T9's actual temperature. After soldering anything around T9's area, allow 5 minutes to cool down before measuring, and re-adjust.


Hi .-)

On a distorted but otherwise playing 200A, ALLWAYS check the 2 fuses on the amp board. Due to the fact that these are soldered into the PCB and their somewhat obscure design, the inner fusing wire gets stressed over the years (warm up and cool down every time you Play) and fails / breaks, even when there was no 'electrical' incident.

So, before doing anything further, check these 2 fuses.


Hi .-)

Audio path: 2x 4558
Tremolo LFO: 1x 1458


The Fender Rhodes Electric Piano / Re: North Facing Magnets
« on: May 24, 2017, 10:14:18 AM »
Look at this vid from Chris at VV:

It shows the importance of having consistend magnet pole direction throughout the pickup rail...


Hi .-)

Anyone experienced using the VV ClaviGel strips on a Clavinet D6 with whammy bar? My thought is that the strings probably may stick / 'glue' on the gel strips, so the strings won't move free when the whammy stick is operated... With yarn, the strings will move free...

Any thoughts on this?

regards, Jenzz .-)

Hi .-)

These 3 are the filter caps for the pickup's voltage supply, so these are not that critical and normally don't have to be replaced.

But due to their mechanical size (and vibration inside the piano), their solder joints are often prone to breakage. So be shure to resolder all joints of these 3 caps.


Hi .-)
This is normal due to the 100nF (Part 18) cap at the power amp Input. With the 3k volume pot, this forms a low pass. I.e., if you turn the volume half way up (1,5k), this forms a low pass at roundabout 1kHz. The more you turn the volume up, the more treble you get....


Hi .-)

First, the 3rd part from the right (which has the thread that goes into the pianos leg flange) has to be fixed to the leg tube (welded or hard-soldered) on the non threaded side.

Put the inner leg into the outer tube with the rubber end-stop facing into the tube...

Now comes the tricky part: Put the 3 1/3 ring pieces around the innter leg while the conicle outside surface of these 3 pieces set into the rim of the outer tube. For securing, the O-Ring must be placed on top of the  3 1/3 rings. Please note that this part only fits in one direction. On the inner side, there is a plain and a conical end. The conical end should go towards the 3 1/3 rings. If all 4 pieces are propper in place, the inner leg should be centered inside the outer tube.
To secure these, put the knurled sleeve over the inner leg and screw onto the outer tube...


The Fender Rhodes Electric Piano / Re: harmonic clarifier
« on: March 12, 2017, 11:41:51 AM »
The big difference will be the signal flow. With the original clarifier, the harp Signal is fed directly into the circuit without the loading caused by the volume and bass boost circuit.

If using the sonic stomp pedal, you will have the volume and bass boost circuit in the signal chain, which causes a little loss of treble and tone clarity.


The Fender Rhodes Electric Piano / Re: harmonic clarifier
« on: March 10, 2017, 02:37:23 PM »
Hi .-)

You should try the BBE Sonic Stomp pedal... Ths circuit is pretty much the same and uses the same custom BBE chip...

..or get the BBE chip elsewhere and build your own, see clarifier schematics in attachment...


Maybe ask him yourself?

There, you can find his mail address.... But i think you have to write in german ,-)

Another cool site dedicated to Ernst Zacharias:

...contains some schematics and tech drawings...

regards, Jenzz

Hi .-)

Ernst is a cool guy, being in his 90's, he lives in Hamburg now and we talk on the phone from time to time. He is still busy on building obscure instruments for himself... Actually, he builds a pipe organ 'without air', using small speakers, mics and amps to get feedback loops through the pipe, while pipe lenghts determing the pitch.

Another actual project is to build a clavinet only with parts from the lumber store/ building market... The only original part will be the pickups and the keyboard Frame.


Other Keyboards & Software Synths / Re: Clavinet E7 No Sound
« on: February 11, 2017, 03:31:06 PM »
Hi .-)

Be sure that all the 4 screws in middle of the PCBs bottom are inserted. 2 of them are used as a ground return for the pickups  via the bracket that holds the Switch caps...


Hi again .-)

Thanks for sharing your findings on the Reussenzehn... Now it is clear for me that the clicking occurs because of the inherent design... There is a small amount of capacitive coupling between the neon bulb and LDR inside the ROACH, which causes clicking because of the steep voltage pulse for the neon bulb... Many amp-techs resolve this by putting a small cap across the neon bulb to smoothen the leading and trailing edges of the pulse... So, maybe this would work on the Reussenzehn, too.

You can't compare a bias tremolo with the TwinReverb style Tremolo or the Rhodes circuits...

Bias trem always uses a sine wave LFO and affects directly the initial gain of the output power stages.

The TwinReverb style trem uses a sine wave LFO + buffer stage, but due to the nature of the neon bulb, it reacts like a square wave LFO... So, the resulting trem waveform is only determined by the reaction delays produced by the LDR.

Rhodes' Peterson preamp uses a simple square wave LFO which drives 2 filament bulbs with an added RC-Network. The resulting trem waveform (that we all love about those preamps) is an conglomerate of reaction delays caused by the Filaments, the RC Network on those Filaments + LDR reaction delay... All of this forms the famous 'cats-eye' trem shape.

Rhodes' Haigler preamp design uses an Op-amp based triangle LFO + added waveshaper. The waveshaper froms a Trapezoid waveform that drives the 2 LEDs inside the Vactrol couplers (LED + LDR inside the small black 'sugarcubes'). So, the trem waveform is formed be the steepness of the Trapezoid and the reaction delay of the LDRs inside the vactrols.

regards, Jenzz

Hi .-)

It's ME who builds / has built the TRamp preamp.... I never got any mail from you.... and i don't have any spam folders... ,-)

mail at:

regards, Jens .-)

Hi .-)

I had a Mk1 witrh the Gresco installed some years ago...

The pots are Bourns 81/82 series pots... Since there is a 'RoHS compliant' marking on the datasheet, these seem to be still available...

See attachment...


The Fender Rhodes Electric Piano / Re: '81 mark 2 action
« on: January 26, 2017, 04:38:55 AM »
Hi .-)

Yes, you can use those, but you need a punching tool like shown in the pic...

regards, Jens

The Fender Rhodes Electric Piano / Re: '81 mark 2 action
« on: January 25, 2017, 04:16:23 PM »
Hi .-)

What about the green felt strips near the front guide pins? Be shure that the key bottoms don't touch these, otherwise the stop-lock mechanism (pedestal / hammer-but interaction) at the pedestal end will not work properly, causing the hammer to wobble after the stroke... To avoid this, you have to add paper punchings on the balance rail Pins. Since these not regular punchings are not offered by any parts supplier, you have to make them your own...

This is common to most unserviced Mk2's with the full plastic keyboard. Because the balance rail pins are big in diameter, the felt washers on the pins are not as wide as usual and get more compressed over the years. This leads to a greater key downward travel, touching the felt Strip....


Hi .-)

The 'click' on the Ressenzehn's tremolo was mentioned by some people here in germany, too (this is why most people in germany prefer the TRamp Preamp, which i had build some time ago...). I don't know the schematic of his Tremolo, so i don' t know how / where the clicking might occur, but if you're not satisfied, you should return the unit...

There is definetly no clicking on the original Peterson design..

regards, Jens .-)

You play vibraphone?

Yes, i returned to Vibes some years ago, having played these back in the 80's in school. But also own a 200A and VV 64 Classic (probably i'm the only Rhodes tech that doesn't own a Rhodes anymore... :-) ).

regards, Jens .-)

On the 200A amp board, the volume change when turning up Tremolo can be adjusted with the red trimmer in the back left side, right before the heat sink. Turning it left will lower the amount of volume change...


The Fender Rhodes Electric Piano / Re: Metallic sounds on release of keys
« on: December 08, 2016, 01:49:57 PM »
Sounds pretty normal to me...

Sometimes, release noise is a bit increased when the damper arm just touches the damper bar when swinging back to its released position.


The Wurlitzer Electric Piano / Re: uneven note volumes
« on: October 28, 2016, 01:25:27 AM »
Hi .-)
As on the Rhodes, striking line is the most important thing to get good dynamics and volume. On a Wurly, you have to heat the hammer stems (hot melt glue) and 'bend' them into the best responding position.

Also, propper reed lenght is important. In the 21 - 42 range, the reeds ends should go roundabout 9mm into the pickup.


Other Keyboards & Software Synths / Re: Clavinet D-6 power supply specs
« on: October 17, 2016, 05:11:15 AM »
Hi .-)

Beware !  Power connector on the D6 is center negative !!  Use a linear supply, not a switching supply, which will probably cause annoying ripple and other artifacts. Any regulated 9V / 100mA supply will do. (...remember, the circuit only needs some mA's...)


The Wurlitzer Electric Piano / Re: Recapping the amp, think twice!
« on: March 01, 2016, 02:17:34 PM »
Except for the strange mild fuzzy distortion.

If you have this kind of mild distortion, check for proper bias in the amp section. Since the circuit of a 270 is the same as a 200A, chances are that the bias current is set too low, causing a mild but audible distortion.

Disconnect the speakers and measure the voltage across R 37. Best setting is between 3 -10 milivolts. If you are below, increase R 58 step by step until you are in that range.


Hi .-)

According to the Clarifier schematic, R 17 should be 10 ohms...


Preamps, Modifications & Upgrades / Re: Harp voltage
« on: January 28, 2016, 03:00:46 PM »
Hi .-)

I think he wants to know the Audio voltage comming from the harp. If you hit a 10-fingered chord hard, you can  get up to 800 mV pp...


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