Pitch Bend Wheel Malfunction

[HarleyRider]

Has anyone seen, heard of or experienced problems with the pitch bed wheel.  Not sure what is happening but from time to time the voice keys get out of tune with the chord keys thus making the overall sound weirdly off.  I have investigated a number of possible causes but my current thoughts focus on the PBW.  It appears that the wheel doesn't always return to center position & wobbles side to side slightly.  The modulation wheel does not wobble at all.  Sometimes when I move the PBW I can produce weird off key sounds that continue even when I release the wheel.  Fussing with it some often will restore operation.  Help, I have a gig coming up Saturday a week from today.

[Janus]

check the pitchband value it can be a halve tone or a compleet octave
or the pitchband is broken inside
try to disable pitchband when it is broken in the mixer
you can play witout the pichband
when the setting is in a reg you need to control al regs

[HarleyRider]

When the sound  is weirdly off key, it remains that way without touching the wheel.  Perhaps there is something else happening that is unrelated to the PBW.  Turning off the KB and turning it back on does not fix the problem.  I use registrations for all my songs which store pitch bend wheel information am not adjusting parameters.

When "something" happens (whatever it is) the result is the voice keys somehow get out of tune with the chord keys making the overall sound unpleasant. I have not yet been able to identify a way to quickly restore proper operation.

[Janus]

When the sound  is weirdly off key, it remains that way without touching the wheel.  Perhaps there is something else happening that is unrelated to the PBW.  Turning off the KB and turning it back on does not fix the problem.  I use registrations for all my songs which store pitch bend wheel information am not adjusting parameters.

When "something" happens (whatever it is) the result is the voice keys somehow get out of tune with the chord keys making the overall sound unpleasant. I have not yet been able to identify a way to quickly restore proper operation.

make a backup off all regs before disable pitchband in them
then after repair you can load them back
when nothings works you have to open the keyboard and disconnect the pitchband from the mainboard
be shure if there are pedals on the keyboard try the keyboard without them

[HarleyRider]

I have determined the malfunction in related to the Pitch Bend Wheel.  If I set its range to 0 the song (voice keys) stay in tune.  If i then set the range to another value (example 2) and then play the song, the slightest movement of the PBW causes the voice notes to be off key.  Slightly touching the PBW will return the voice key to proper pitch.  It appears that "playing" the KB causes enough vibration to cause the PBW to malfunction!

The new problem is "How to repair the Pitch Bend Wheel in less than a week"!

[Janus]

I have determined the malfunction in related to the Pitch Bend Wheel.  If I set its range to 0 the song (voice keys) stay in tune.  If i then set the range to another value (example 2) and then play the song, the slightest movement of the PBW causes the voice notes to be off key.  Slightly touching the PBW will return the voice key to proper pitch.  It appears that "playing" the KB causes enough vibration to cause the PBW to malfunction!

The new problem is "How to repair the Pitch Bend Wheel in less than a week"!

Go to a chop for repair and loan the same keyboard
or  tape the pitchband in neutral stand
If that not work you have open the keyboard and disconnect it from the motherboard
You can play without pitchband

[HarleyRider]

I have now talked to several keyboard players in my area - south Texas - where they perform a lot for Winter Texans who come south for the warm climate in the winter.  Turns out the "wearing out the pitch bend pot" is actually quite common.  We do a lot of guitar and sax voices that utilize the pitch bend so NOT using it is not a good option.

Luckily the part can be purchased from several sources. Ordered it today ($6.95) and paid for express mail ($30 extra) and should be here either Monday or Tuesday.  If all goes well I"ll be OK for my Saturday show.

[ikmusic]

Let know if the exchange has helped.

[Toril S]

Are you going to open the keyboard and change it yourself? In that case it would be very interesting if you made a video! But I guess you are busy with gigs Good luck! All the best from Toril

[RoyceM]

Here is my experience from last November:

I severely jostled my stack of equipment (my stand rides atop my S975 keyboard in a carry bag) trying to roll up a ramp and through the door of a group home I was entertaining. During my performance, I went to use my pitch bend wheel and noticed it out of position and wobbly. Later, when investigating it at home, it worsened so much that I couldn't play because it sounded so out of tune.

My local Yamaha technician scrambled to overnight the inexpensive parts for me before he opened up the S975 in order to meet timing for shipping purposes. When he got the keyboard open the next morning, he realized he could make the repair using a used wheel he had on hand. The original wheel had broken, but the electronics were OK. As he has often done for me, I was back in action without missing a gig that same day.

For 14 years I had transported my equipment this same way, but this time a problem happened. Now I put a protective piece of foam over the wheel/knob assemblies when I zip the carry bag.

I figured I probably was the only person to break a pitch bend wheel.

- Royce

[Janus]

Are you going to open the keyboard and change it yourself? In that case it would be very interesting if you made a video! But I guess you are busy with gigs Good luck! All the best from Toril

There is a trick to do that
Make  photo's from every step you make
special the connections you have to break
they are mounted with clips on the motherboard

Gr.Jan

[Janus]

Are you going to open the keyboard and change it yourself? In that case it would be very interesting if you made a video! But I guess you are busy with gigs Good luck! All the best from Toril

There is a trick to do that
Make  photo's from every step you make
special the connections you have to break
they are mounted with clips on the motherboard

Gr.Jan

[HarleyRider]

The part is in and installed, and I have verified it is the correct part.  The pitch bend control worked, did not wobble, and did not seem to be upset by the vibrations of playing the keyboard.  However, it has to be set to 3 in order to actually pitch bend the note by 1 semitone.  I took the KB apart to investigate any possible installation screw ups.  I even got out an ohm meter to make sure the parts were identical, no soldering issues or anything else.  Nothing improper was found.  Im about ready to put all the screws back in, but am wondering if there is some kind of "reset" or something like that, that I should do to make sure the all the electronics/software are functioning properly.

Any thoughts?

[travlin-easy]

There is no setup for the pitch bend wheel that I know of, but I would suggest doing a master reset and resetting all parameters after screwing the board closed. There may be something I don't know of in the master reset that would address the wheel.

Good luck,

Gary

[HarleyRider]

How do I do a master reset and reset all parameters?  Since all electronic parts including potentiometers have manufacturing tolerances I wont be able to find one that is exactly the same.  The one originally installed measured 9.9K,  the new one I installed was 10.6K.  Yamaha tells me the nominal value is 10K but could not give me a tolerance on the 10K.  At center position the pot is somewhere close to mid range but when moved up or down, movement is limited by the knob not the pot.  It seems like the circuitry would somehow need to simply "learn" what the resistance change from peg to peg would be, factor in the pitch bend setting and do its thing.

[travlin-easy]

Merely go to Function/Utility/system reset and then select all the boxes on the lower left side of the display. Then press Factory Reset Execute, which restores the keyboard's electronic system to factory default. Be sure to back up all user files to a USB drive as they will be erased from the onboard memory.

Hope this helps,

Gary

[overover]

... It seems like the circuitry would somehow need to simply "learn" what the resistance change from peg to peg would be, factor in the pitch bend setting and do its thing.

Hi HarleyRider,

I recommend to do the following steps:

1. Download the PSR-S750 SERVICE Manual here: https://psrtutorial.com/lessons/workshops/ServiceManuals.html

2. Read page 56 ("PSR-S750 Test Program") of this Service Manual.

3. Switch OFF the S750. Press and hold the three keys C#2, F2 and G#2 (= C# Major chord in the second octave) while powering on the S750 (until "TEST" appears on the LCD).

4. Go to page 60 of the Service Manual and read the description of Test #28 (Pitch Bend Wheel Check).

5. Select Test item "028 : Pitch Bend Wheel Check" by using [Tempo +/-] buttons OR [Data entry] wheel.

6. Do the Test #28 as described on page 60:

When the test is started, " Pitch Bend Up 128 " is displayed.
Set the [PITCH BEND] wheel to the maximum position and check that the G3 sound is pro-
duced and " Pitch Bend Down 255 " is displayed.

Set the [PITCH BEND] wheel to the minimum position and check that , the C3 sound is pro-
duced and " Pitch Bend Center 0 " is displayed.

Set the [PITCH BEND] wheel to the center position and check that the C4 sound is produced
and " OK 0 " is displayed.

IF "OK 0" is finally displayed, the PB Wheel should work properly.

7. Select Test #44 to EXIT the Test Program. (Do not turn off the power until the main screen is indicated after executing the Test Exit!)


Hope this helps!

Best regards,
Chris

[HarleyRider]

 I installed a new 10K pot that shipped from Yamaha and I downloaded the manual and performed all the tests including 28.  Everything passed except 28.

Initial position (center) of the pitch bend pot read 128 as specified.  When I pushed it up to max, the screen readout said 180, rather than 255.  When I pushed it down, it read 75 rather than 0, and the test failed.  When I measured resistance on the actual assembly after installation of the pot, everything tested correctly.

I also did a system reset with no help. 

There is no mention of any corrective action that can be taken if the test fails.  The parts list which is part of the service manual indicates that I can purchase the circuit board assembly with the pot already installed.  I checked with Yamaha24x7.com and the assembly is in stock and costs $18.44.  I will purchase this part and install it hoping it will solve the problem.

[HarleyRider]

For those interested, I ordered, received and installed a pitch bend circuit board.  The pitch bend wheel now functions properly & passes the maintenance manual test.

Before installation I closely measured the resistance of each variable resistor while mounted on their boards.  The pot I purchased & installed or the original circuit board measured 10.7K.  The one installed on the new circuit board measured 9.07K - very close to the original pot that no longer functioned due to a mechanical failure of is shaft.

My conclusion is that the circuit is resistance dependant & Yamaha tests their circuit boards & probably select pots that are at the low end of a +/- 10% production tolerance.  Shipped out pots may not be selected before shipment.

The pot itself costs about $15 with tax & shipping.  The bad pot needs to be unsoldered from the old board & the new soldered back on & it may or may not work!

The circuit board with pot is about $28.  Remove 2 screws & disconnect 1 cable, & install the new board.  Much easier & will probably work!

[HarleyRider]

I have received several PMs to document my repair of the pitch bend wheel.  It really sucks when you take 45 minutes to document the repair and attach 3 photos.  After getting everything done, I clicked the "Post" button.  The forum then notified me that the attachments were too large and deleted the whole thing.  Sorry folks, Im not going to take another 45 minutes to re-document the repair.

A short version is:

1. Set the KB upside down on a work surface.  Support the KB at the left and right edges so the keys and wheels do not touch the work surface.  Remove screws that hold the bottom and top cases together taking note of where the various length screws go.  Set the bottom case behind the top case. Additional help is desirable since some of the cable ties must be loosened - Photo1.

2.  The 2 smaller circuit boards (tall and narrow) in the lower right of Photo2 are the wheel boards - the one on the right being the pitch bend.  Remove the cable, screws, and jigger the board left to right to free the wheel from its upper case mounting.

3.  Photo3 shows the removed circuit board.  I prefer purchasing a new circuit board (no soldering) as Yamaha likely tests assemblies but not components.  Reverse all disassembly steps to install the new board, and put the KB back together.  You can then confirm proper operation by playing the KB and/or using the test method described in an earlier post.

Confirm correct part numbers with Yamaha24X7 before you purchase.  I have been told that the 750 uses a different part number board than is used in the 950.

I will post the photos separately.

[HarleyRider]

Sorry folks each of the photos is too large to be used as an attachment.  I tired of trying.

[overover]

Sorry folks each of the photos is too large to be used as an attachment.  I tired of trying.

Hi HarleyRider,

thank you for your repair report!


The file size of attached pictures to posts is limited here on the forum.

You can RESIZE the pictures, e.g. by using an online service like "https://resizeimage.net", or you can upload your photos to a picture hosting service like "www.directupload.net" or to cloud storage service like Dropbox or OneDrive.

Then post the links to the pictures here or use the IMG tag (button "Insert Image") to display a picture directly in your post.


Best regards,
Chris