Messages

1

Parts, Service, Maintenance & Repairs / Re: Rhodes Help

« on: August 03, 2020, 11:58:02 PM »

When you say "feedback," do you actually mean buzzing noise? 

[Or do you mean "feedback" - an oscillating howl created by the amplified resonance between the speaker and a microphone?]

Look for obvious problems first (is there a short or broken wire at the RCA connector, does any wire look out of place or broken), but you should expect that it could be dead pickups. 

Get a cheap volt-ohm "multimeter" and check the harp for continuity. 
This cheapie multimeter will work fine:  https://www.harborfreight.com/7-Function-Digital-Multimeter-63759.html

See https://ep-forum.com/smf/index.php?topic=10307.msg57408#msg57408
and the links at the bottom of that post.

Come back at us with any new information or developments.

Is it a stage piano or a suitcase?

Sean

2

The Fender Rhodes Electric Piano / Re: '73FR73 Will hardware store washers work just as well on tonebar 

« on: August 03, 2020, 06:00:35 PM »

Unless your existing washers are offensively nasty and rusted, you should just re-use the existing washers.

3

The Fender Rhodes Electric Piano / Re: '73FR73 Will hardware store washers work just as well on tonebar 

« on: August 03, 2020, 04:43:05 PM »

The tonebar washers I have are:
0.432" in diameter (just under 7/16", very close to 11mm)
0.187" center hole (3/16", well under 5mm)
0.045" thick (3/64", 1 and 1/7 mm?  HA)


Let's see what we can find online:  Bingo!   https://www.mcmaster.com/91950A046/

SAE #8.  (General Purpose washers won't be the right size or thickness, you want SAE.)

https://www.homedepot.com/p/Everbilt-8-Stainless-Steel-Flat-Washer-50-Pack-800022/204276447


Sean

4

Parts, Service, Maintenance & Repairs / Re: Painting a Rhodes Mk 1 Harp Cover

« on: July 29, 2020, 08:17:01 PM »

Looks pretty sweet!

I also like the paints booth!  Great idea.

Sean

5

The Fender Rhodes Electric Piano / Re: Fender Rhodes Mark 2

« on: July 28, 2020, 12:40:52 PM »

Ja! Bitte poste Fotos!

...Ich hoffe, die Tonabnehmer haben kein weißes Klebeband.

(Leider spreche ich kein Deutsch.  Ich kann nur ein paar Sätze in Google Übersetzer machen.)


Sean

[Yes, please post photos.
...I hope the pickups don't have white tape.]

6

The Fender Rhodes Electric Piano / Re: Fender Rhodes Mark 2

« on: July 28, 2020, 12:33:40 PM »

Dies wird eine Herausforderung sein...  Kann einer unserer Techniker hier Deutsch?


[This will be a challenge... Do any techs here speak German?]

7

The Fender Rhodes Electric Piano / Re: Fender Rhodes Mark 2

« on: July 28, 2020, 12:22:20 PM »

Google Translate thinks he said:

Hello everyone,
I got a Fender Rhodes Mark II from my basement a few weeks ago from my father.
I immediately organized an amplifier and connected the piano to my system.
Then I noticed that the lower half is quiet to no sounds.
Since I am only 15 I am familiar with it and do not know exactly what to do now.
I appreciate every tip.
I can also send photos if necessary
LG

8

The Fender Rhodes Electric Piano / Re: Replaced 1st low E note Tine and doesn't sound good and can't tune it low enough

« on: July 27, 2020, 06:42:58 PM »

JB,

Get a vise.  If you want sustain, get a vise.

Sean

9

Parts, Service, Maintenance & Repairs / Re: Trying to verify all pickups are doing their job.1973 Stage FR '73

« on: July 27, 2020, 06:34:23 PM »

JB,

When you tap a screwdriver against those pickups, you hear a loud POP through the amp, correct?  (that means the coil is intact)
Can you feel the pull of the magnet on these pickups?  (To confirm that the magnet is still inside the pickup bobbin.)

If you just said "yes" twice, then...

If you can make the tines vibrate, but do not get any sound from the pickups, then the tine is NOT close enough to the pickup.  It may be too far back, it may be too far above, or it may be too far below.  (Remember, a short tine without a tuning spring will make almost no sound or sustain at all, so test on a tine that has a tuning spring installed.)
__________

You can easily test the swing of the hammers and see exactly where they contact the tines: 
1.  Remove the screws at each end of the name rail, unplug the grey cable that goes to the back left corner of the harp, and set the name rail aside.
2.  Reach your hand in from the front, and lift the hammers manually with your fingers.

Then you will see where the hammer is going to hit the tine, or where it bangs against the tine block, or the end of the damper arm.

Sean

10

The Fender Rhodes Electric Piano / Re: Is a 30watt Crate Amp not powerful enough for '73 Rhodes high end notes/sounds?

« on: July 24, 2020, 01:51:23 PM »

JB,

You cannot adjust the position of the hammers.  You can only move the tines or the pickups. 

You have five ways of moving the tines:
1 - fiddle with the "timbre" tone-bar mounting screw
2 - fiddle with the "escapement" tone-bar mounting screw
3 - add or remove shims from the harp supports
4 - slide one or both ends of the harp forward or backward (this adjusts the "strike line")
5 - if the tine is mounted off-center, loosen the tine-block mounting screw, and align the tine so that it is straight

You have two ways of moving the pickups:
1 - loosen the screw, and slide the pickup a tiny bit forward or a tiny bit backward
2 - if the pickups seem abnormally high or low, you can very delicately bend the aluminum tang to get the pickups to sit right (straight is best, but... you gotta do what you gotta do.  Be careful not to break the pickup bobbin off the tang.)

In the situation that a tonebar is leaning down so much to get the tine facing the pickup, bend the pickup to sit higher, and the tonebar won't be leaning down so much that the tine block is pinned against the rail.

Are these new tonebar grommets or old tonebar grommets?  New grommets will fix (or change) lots of positioning issues.

To re-install the tuning spring, you should remove the tonebar and tine from the harp, and hold it steady in a bench vise.

Sean

11

The Fender Rhodes Electric Piano / Re: Is a 30watt Crate Amp not powerful enough for '73 Rhodes high end notes/sounds?

« on: July 24, 2020, 02:41:46 AM »

JB,

Tine 72 and 73 need tuning springs.
The tine block for tine 72 is pinned against the tonebar rail, so it will be damped.
Tine 71 is well above the pickup, and the pickup is extended too close to that tine.  Tine 73 may be too high as well.

Have you adjusted the tonebars so that they are about 3/8" above the surface of the rail?
Adjust the escapement screw so that the distance from the bottom of the tonebar to the top of the rail is 3/8. 
Look right here at the place where the #1 arrow is pointing:




Use a 3/8" block as a feeler gauge (we all use the mounting block from an old broken tine).  Then adjust the timbre screw so that the tine is pointed at the tip of the pickup (and re-check the 3/8" gap again), then adjust the pickup so that it is nice and close to the tine. 

Take a look at chapter 4 of the repair manual, and search this forum for "strike line."

Sean

12

The Fender Rhodes Electric Piano / Re: Mark II (wooden key) restoration questions

« on: July 22, 2020, 04:14:37 PM »

Don't worry about your tines yet.  Yes, definitely replace the grommets, you will be surprised how much of a difference that makes.

Your damper felts look great.  The one that leans can be re-glued, or gently convinced with a little glue at the base to sit up straight and eat his peas.

I think you should go for new hammer tips, because you don't like the current dried-up and hardened ones.  Newer softer tips will sound different.  If nobody here has guidance, call Chris or Fred at VV and discuss it.  They will help you decide which style tips to get.

I would leave the pedestal felts as they are.  They don't seem to be any problem - you don't seem to be hating the action in the video. 

Sean

13

The Fender Rhodes Electric Piano / Re: Is a 30watt Crate Amp not powerful enough for '73 Rhodes high end notes/sounds?

« on: July 22, 2020, 02:10:09 PM »

SteveO - hah!  I beat you by 77 seconds.

Wanna race on the next one?

 

14

The Fender Rhodes Electric Piano / Re: Is a 30watt Crate Amp not powerful enough for '73 Rhodes high end notes/sounds?

« on: July 22, 2020, 01:18:46 PM »

JB,

RTFM  http://www.fenderrhodes.com/org/manual/toc.html
Bookmark this site:  http://www.fenderrhodes.com/

Especially see:  http://www.fenderrhodes.com/org/manual/ch4.html#4-7
See also http://www.fenderrhodes.com/service/tine-settings.html

Play around with the pickup position and the timbre adjustment screw.  You will find your sound.

The timbre adjustment screw is the leftmost screw/spring in this diagram:
http://www.fenderrhodes.com/org/manual/ch4.html#fig4-3
(That is the tonebar adjustment screw that is closest to the rear of the piano, closest to the pickups.)

To make the notes louder, you can slide the pickup closer to the tine tip - loosten the pickup mounting screw, gently nudge the pickup to get it unstuck from 47 years of living in one place, then slide the pickup forward so that it is closer to the tine, gently re-tighten the pickup mounting screw.

Have you confirmed that the hammers are indeed contacting the tines?  If the escapement is abnormally high, sometimes the hammer will hit the end of the damper arm before it gets to the tine.



Sean

15

The Fender Rhodes Electric Piano / Re: Found a 1970 Fender Rhodes Mk I Stage 73 Missing its Keys. Is it savable?

« on: July 21, 2020, 04:31:32 PM »

... only about 460 miles away.  Nine or ten hours of driving each way, plus $70 of gas each way.  Hmmm....  Ouch.

16

The Fender Rhodes Electric Piano / Re: Found a 1970 Fender Rhodes Mk I Stage 73 Missing its Keys. Is it savable?

« on: July 21, 2020, 04:08:52 PM »

TC,

I have exactly what you need. 

I have the remains of a c.1973 Rhodes action:  73 Pratt-Read full-skirt keys on a keybed, wooden action rail with half-wood hammers, bridle straps, individual damper arms, and tooth-root damper felts. 

It is missing the harp, missing case, missing balance rail felts and front rail felts, missing the name rail, and strangely missing the wooden support for the action rail (the strip of wood that goes between the keybed and the action rail).  I think I have the cheek blocks too. 

The action is now clean, but still needs some work.  The balance and front rail pins were rusted, and have been sanded down.  They are not as smooth as ideal.  About 22 of the keys stick (they don't return on their own volition), and need to have their sides sanded down until they no longer touch their neighbors.  (Two keys at the bottom, two keys in the middle, and then nearly every single key in the top two octaves.)  This means that the action was exposed to water, and the keys are warped (or maybe just swollen?).  However, every single key looks perfectly straight when removed from the action.  I think they all work when I remove the neighboring keys, but I should test that to verify.   Every key pedestal seems to mate with the key above just perfectly, so I don't think this action is too far gone.


Where on planet earth are you?  Toronto?  I am in USA, near Washington DC.  Send me a PM with your email and phone number.

Sean

17

Parts, Service, Maintenance & Repairs / Re: No sound from 62 thru 73 keys on a 1973 Fender Rhodes Stage 73..help!

« on: July 20, 2020, 01:30:46 PM »

JB,

You can tap the tip of the pickup with a screwdriver, and it will make a LOUD pop and clank as the magnet makes the screwdriver slam against the pickup tip - so turn the amp gain way down.  I have done this, but it is never an enjoyable method, and you don't really need to put your speakers through this torture.

However, it does help in the situation where you have one very quiet note, but you refuse to believe that the pickup is dead.  If one pickup is dead in a group-of-three, the neighboring pickups will still create some current in reaction to the moving tine.  The note with the dead pickup will sound quiet and ghostly, but audible.  If you tap the pickup on the quiet note, you will get no loud pop when the magnet grabs the screwdriver.  Then you can confidently declare the pickup dead.

Sean

18

Parts, Service, Maintenance & Repairs / Re: No sound from 62 thru 73 keys on a 1973 Fender Rhodes Stage 73..help!

« on: July 20, 2020, 12:56:59 AM »

JB,

My Ouija board says that the loops of wire between pickups running along the back solder terminals is touching a little loop of wire that connects the front solder terminals.  This could be anywhere in that group of three, so at pickup 61F, 62F#, or 63G.  But that would only short out three notes.   Hmmm... could this be the problem in each of the groups above that?  I doubt it.

It could be that the pickups are all pulled back away from the tips of the tines, or that the pickups are not well-aimed at the tines, of that the treble on the Crate was turned all the way down, or that the strike line is way off so that the hammers are not hitting the tines, or that all the tuning springs on those notes have evaporated, or that your ears are broken and can't hear above 1390Hz (run to the doctor!  You are the patient zero!).  Check some of these ideas, ignore others.

I really enjoy guessing out of the blue, but photos always help.

Sean

19

Parts, Service, Maintenance & Repairs / Re: 1973 Fender Rhodes Stage 73... Can't get sound when I hook it up to an amp.

« on: July 17, 2020, 03:13:51 PM »

JB,

Your Rhodes almost certainly has a few dead pickups.  (I love the 1973 year for Rhodes Pianos - half-wood hammers, square hammer tips, tooth-root-like damper felts, full-skirt keys, very sharp edges and nose on the black keys, etc.)

The pickup rail is wired with pickups in groups of threes.  This is a series of 24 groups of [three pickups in parallel]  (one group of four at the low end).  Each group of three pickups in parallel looks like this:


If all three pickups in any [group of three] are dead, then the whole piano makes no sound.  The pickups die for one an only one reason:  the thin winding wire has broken (usually from corrosion at the spot where the wire leaves the winding and bends around the end of the bobbin before it reaches the solder terminal).

Here is some advice plagiarized from the links below:

Dead pickups are the most likely problem, but a super-dirty RCA jack is a possibility.  Obvious missing wires or broken solder joints should be found with a careful eye and a flashlight.  You need some simple tools:  a cheap volt-ohm meter, a bunch of alligator clips, a bright flashlight, an RCA-to-quarter-inch adapter, and your guitar amp.

I would start with the volt-ohm meter, and set it to read in the range up to 20K-Ohm.  Unplug the RCA cable from the back left corner of the harp, and touch your ohm-meter probes to the center terminal of the RCA jack, and the solder lug that is connected to the long black squiggly wire that runs behind the row of pickups.  If you get a reading of something between 1000Ω and 2000Ω, you would jump for joy!  (A perfect harp would read ~1425Ω.)  If you get a reading that indicates an open circuit (infinite ohms), then you have a few dead pickups.   In the rare case that you get a dead-short (zero ohms); then you have to find the mis-wired connection, or the debris or solder blob stuck in the RCA jack that is causing the short.

Buy a bag of six jumper wires with alligator clips on both ends.  (Search online for "clip leads" and spend five or ten bucks for a bunch.)

Use the alligator clips to short out large sections of the pickup rail, and you will quickly be able to narrow it down to which section has the dead pickups.  If you are really unlucky, you may have to short out nearly all of the piano, but probably not. 

If you try to short out an octave at a time, and play the other notes, you will probably get lucky and find the dead section pretty quick.  If not, then use your best and favorite curse words while you short out the bottom octave, and then also short out another octave while playing around hoping for sound.  If that doesn't work, short out the bottom TWO octaves, and then again the other spans here and there while you plink away. 

When you finally get sound, you know that the group of dead pickups is in the regions that you have shorted out. 

Then you can move the alligator clips closer together to short out fewer and fewer pickups until you identify the dead individuals.  Mark the dead pickups with a magic marker.  Then those are the only ones you have to keep shorted, and replace or repair.

Another way to search for suspected dead pickups is to get your brightest flashlight and a good magnifying lens, and look closely at the tiny wires on each pickup as they leave the soldered connection on either end of the winding.  Usually, you will see a tiny green speck of oxidation at the end of the broken wire, or sometimes you might even see that the wire is indeed broken.

Read some of these posts that discuss finding the dead pickups:
https://ep-forum.com/smf/index.php?topic=9989.msg55589#msg55589
https://ep-forum.com/smf/index.php?topic=10079.msg56090#msg56090
https://ep-forum.com/smf/index.php?topic=7116.msg36655#msg36655
https://ep-forum.com/smf/index.php?topic=5620.msg27734#msg27734
(Some circular references.)

Basic method of replacing pickups:
http://www.fenderrhodes.com/service/pickups.php

Sean

20

The Wurlitzer Electric Piano / Re: Wurlitzer 200 Audio Input

« on: July 14, 2020, 05:04:29 PM »

Eau Claire,

Vintage Vibe has a reasonably readable copy of the wurly schematics online:
https://cdn.shopify.com/s/files/1/0666/2821/files/Wurlitzer_200_and_200A_Service_Manual.pdf?8872610067384662061

Go down to page 43 and 45 and right click and select "rotate clockwise."

The schematic on page 43 shows you the resistor values that Wurlitzer used for a voltage divider to provide "tape in" aux; and with no resistors, it would be "microphone in" or "phono in" (without RIAA EQ).  Note that this section of the circuit is isolated from the high-voltage (low current <0.3mA) on the harp by capacitors 55 and 58.

The diagram on page 45 shows you where the connection terminals (3) and (1) are on the left side of the board next to the RCA jack.  (Note that the diagrams for the 200, on page 40 and 42 show the board upside down, so the "mic in" terminals are on the right side, next to the RCA jack.)

If you really are going to carve up your wurly to add an effects loop, you could lift one end of R45 out of the pc board, take the "send" signal from the end of the trimmer pot, build a buffer amp to bring it up to the level that works with your effects, and then just return the signal to terminal (3) through the "tape in."  You could use a switched TRS 1/4" jack (Switchcraft 13b or 14b) to take the effects loop in and out of the audio path, and use an effects loop Y cable.  That doesn't sound super-convenient, just to add phaser, flanger, or delay through the on-board speakers.  I would leave it as-is and use the AUX out and an external amp.


Sean

21

Parts, Service, Maintenance & Repairs / Re: Rhodes M2 Clacking keys problem

« on: July 09, 2020, 09:51:45 PM »

Hey Javartin,

Is your complaint about the bonk or click sound that the hammer makes when it contacts the tine?  (The top ten hammer tips are made of maple wood wrapped with shrinkwrap.  It takes those hard hammer tips to make those super-short tines ring.)

or

Is your complaint about the noise of the key-return - where the back of the key falls and bounces, and the hammer falls and bounces against the pedestal?

Sean

22

Other Keyboards & Software Synths / Re: Pianet CH Radio Circuit and Pickups

« on: June 28, 2020, 03:16:19 PM »

http://clavinet.com/schematics.php  has a schematic for the CH amp:   http://clavinet.com/Pianet_CH_amp_schematic.pdf

Sean

23

The Fender Rhodes Electric Piano / Re: Power down when vibrato switched on

« on: June 25, 2020, 06:51:31 PM »

Will,

With the preamp disconnected, what do the power feeds coming from the amp cab measure?  (Be careful not to short the pins with your meter leads, it makes an impressive spark.)  The voltage should be very stable, and unwavering, and less than half a volt off the perfect + and - 15 volts.  If they are not close to 15V, then you should replace the 7815 and 7915 regulators (and probably the nearby electrolytic capacitors).   See http://www.fenderrhodes.com/org/ch11/fig11-3.jpg  These regulators create a lot of waste heat, so make sure you get them tight to the heat sink.

[Start making a shopping list of components.  If you are going to pay for shipping or a minimum order, you might as well get extra toys.  Buy yourself a few cheap/disposable solder suckers and some solder braid - oh, I mean solder wick, um solder-removal braid.]

But even if those regulators are bad, that doesn't explain the bad behavior on the preamp board.  Don't give up on your search for a short between traces, and take a good look at the PC board where the switch mounts, and make sure the solder blobs are not making a bridge between traces.

If you suspect that your preamp board is not grounded correctly, check the thin wimpy wires that come from the XLR to the board.  Make sure the connections are clean and tight.  (Also check your 5-pin cable for continuity of the ground terminals from end to end of the cable, and from the board to the far side of the cable.)  Make certain that XLR connector pins are clean and making good contact.

The 2N3392 is a cheap component, and easy to swap out, as are the op amps.  And as long as you are heating up your soldering iron, you should replace the electrolytic capacitors on the preamp board.  If replacing an IC, order a few of the correct size IC sockets, so that future op amp swaps are simple.

When you buy new opamps, get a handful of NE5532 or SE5532 opamps to replace the 1458 opamps that are in the audio path.  You will be able to hear the difference.  When you shop for chips make sure you get the PDIP package, not one of the surface-mount flavors.  PDIP is becoming obsolete on some opamps.  (Leave the oscillator opamp as a slow-slew-rate 1458 chip, unless you are willing to be the guinea pig.)

Even if the oscillator op amp is fried, it shouldn't take down the supply rails.  You should be able to dead-short across pin 8 to pin 4 without making the voltage regulators break a sweat.  Check that the 100Ω current-limiting resistors are still in good shape (see R19, R20, R21, and R22) and close to 100Ω.

Sean

24

The Fender Rhodes Electric Piano / Re: Power down when vibrato switched on

« on: June 24, 2020, 02:04:45 PM »

Will,

Yep, Fig 11-1 goes with your 013488 preamp.  I don't have that version preamp, but.... 

I guess the first thing I would do is make sure that the preamp has no possible way to come in contact with the aluminum enclosure.  (My Janus preamp got fried when the back left corner touched the metal chassis, and that burned off some traces.  Previous owner had to do some major repair.)   You should put a thick piece of plastic, formica, kapton, or cardboard underheath the preamp PC board.  If and circuit board is simply mounted by the front panel controls with no standoffs under the board, it should have an insulator underneath.

Also, take a very close look at the underside of your PC board to make sure there are no traces with solder blobs touching an adjacent trace. 

Check the tremolo/vibrato switch itself - does it short either circuit terminal to the switch body? 

Then I would be curious to know if the tremolo oscillator is actually running.  (I assume you don't have an oscilloscope.)
When you flip the "vibrato" on, do you get tremolo?   

Are you saying that removing the LED causes the symptoms to occur, or are you saying the symptoms will show up with or without the LED?

Sean

25

The Fender Rhodes Electric Piano / Re: Power down when vibrato switched on

« on: June 23, 2020, 05:29:47 PM »

Will,

Which preamp board do you have?  It should match one of these schematics:
Schematic for Janus preamp with sliders: http://www.fenderrhodes.com/org/ch11/fig11-1.jpg
Schematic for Janus preamp with sliders, version 2: http://www.fenderrhodes.com/pdf/late-mark1-suitcase-janus1.pdf
Schematic for Janus preamp with five knobs: http://www.fenderrhodes.com/pdf/late-mark2-suitcase.pdf

The preamp board will have a part number on it.  What is it?   Something like 015244 or 018017 or 013something.


Sean

26

For Sale / Re: Shipping now! "Classic Keys" book, a celebration of vintage keyboards

« on: June 11, 2020, 02:41:15 PM »

Awesome idea.  I just sent the link to my wife.  ...Crossing my fingers that she thinks I am worth three internet clicks.

Sean

27

Parts, Service, Maintenance & Repairs / Re: Dyno Rhodes External Power Supply?

« on: June 08, 2020, 05:41:05 PM »

Stevie Keyz,

Here are the facts:

1.  If there is no power-on LED on your Dyno power supply, then it certainly doesn't match VV's scribbled schematic.  Not knowing what circuit you are using to charge your lithium-ion batteries is not great, and possibly dangerous.

2.  Un-protected lithium-ion batteries are known to dramatically fail when over-charged.  See https://www.powerelectronictips.com/heres-what-happens-when-lithium-ion-batteries-are-drastically-overcharged/

3.  Your little 9V batteries are built with two internal batteries in series, each providing 3.7 to 4.2 volts.  So your batteries will provide 8.4 volts when fully charged (only 7% less than nominal 9V, so no biggie). 

4.  I have no idea how robust and reliable the internal protection circuitry is inside your lithium-ion rechargeable batteries.

Chargers built for lithium-ion batteries have protection circuitry that shuts off the charger when the battery reaches full charge.  Since lithium-ion batteries (when in good condition) do not drain themselves quickly (like NiCads and NiMH batteries do), there is no trickle charger used to top them up.  (Trickle charging a fully-depleted battery may not even work, and even if it did, it would take days, not hours.)

Well, anyway, I agree that I have not fixed your problem.

Sean

28

Parts, Service, Maintenance & Repairs / Re: Dyno Rhodes External Power Supply?

« on: May 29, 2020, 05:56:09 PM »

Stevie,

Using a different wall wart to power this circuit will not fix your Li-ion battery charging problem.

I assume that the circuit was designed for an AC-AC wall wart transformer, not the 15V DC supply you are using.  However, if your 15V DC supply is working, then keep it.

The 15V DC input will probably make the power-on indicator red LED run hot and bright, but as long as that LED is okay with 50mA and the resistor doesn't burn up from the 0.675 Watts (it is rated for only 0.500 Watts), AND that the input voltage is high enough that the 78M15CT regulator doesn't go into cut out, well, you are fine.*

If this were my Dyno, I would swap the current limiting resistor that feeds the power-on red indicator LED with a 1KΩ 1/2-watt resistor (the LED should light up just fine with 13.6mA).


* The input voltage to the 78M15CT regulator is supposed to be two volts higher than the output.  The spec sheet lists the "Dropout Voltage" as 2.0V.  But if the circuit isn't sputtering and shutting off, then the regulator is working fine. 


Sean

29

Parts, Service, Maintenance & Repairs / Re: Dyno Rhodes External Power Supply?

« on: May 29, 2020, 05:29:38 PM »

Stevie,

I would not use this circuit with Lithium Ion batteries.

Assuming that the scribbled schematic is correct, it is a trickle charger.  It probably was expected to charge at less than 20mA, to keep it within the safe operating limits of the green charging indicator LED.

If you want to keep your Li-Ion batteries in the Dyno, you should disconnect the charging circuit (un-solder or clip one end of the 270Ω resistor that is next to the green LED).  This way, the Lithium-Ion batteries are never connected to the trickle charger.

Get an external charger that is designed specifically for Lithium Ion batteries.

Sean

30

The Fender Rhodes Electric Piano / Re: Fender Rhodes MK I Stage 73 Missing Sustain Rod Piece

« on: May 28, 2020, 03:06:46 PM »

The little collet?  I haven't seen a replacement part available.

I have search for "collet", "locking collar", "turreted grommet" - no luck. 

Try calling Chris and Fred at Vintage Vibe, and ask if they have one sitting in the junk drawer.

You could easily install a locking collar on top of the clutch, like a Rogers Memriloc. But you would have to adjust it with an allen wrench.
1/4" stop collar - https://www.mcmaster.com/6462K12

Sean