Broken keyboard

[AnupamEnosh]

At my music classes, where I teach a few beginners, there is a damn old and average condition-ed PSR-E333, which has some sort of Touch sensitivity problem, it plays the notes on lower velocity, but at higher velocity, it does not sound at all. Same happens when TouchRes is turned off. This happens with the D-note and G#-note of each octave of the keyboard. Also, at times those mentioned keys play the sound extremely hard with the touchres not working at all. What kind of issue might be lying underneath, and is it economic to get it repaired, or to get a new keyboard ?

[SeaGtGruff]

I don't know anything about the hardware side of keyboards, but you can get the service manual here:

https://elektrotanya.com/showresult?what=PSR%20E333&kategoria=&kat2=all

If it's just a matter of opening up the keyboard and cleaning it thoroughly then that would be cheaper than replacing it. There are videos on YouTube that show people opening up their keyboards to clean and repair the key assemblies.

But given its age, and the fact that fixing it might give it only another few months or years of usage, it might not be a bad idea to replace it with a newer model that's still under warranty.

[vbdx66]

Or else I regularly see second hand PSR E333 and 343 for sale for under 100 €. It might be a solution if you manage to find a nice unit (some people buy these keyboards for a kid which either promptly switches to a proper piano or in the contrary completely abandons music, so some of these keyboards are practically unused).

Best Regards,

Vinciane.

[Jean-Pierre 33]

Hello Anupamenosh,

With the help of the Service Manual obtained on Electrotanya, you just have to dismount your keyboard and clean the "Rubber Contacts" (kind of carbon rubber that are placed under the keys see pages 12 and 13 of the Manual Service) and the contacts of the circuit board on which they support with a bomb type W 40 and Q-Tip.

If that's not enough, Yamaha's SAVs sell these "Rubber Contacts" for all types of Yamaha keyboards.

Best regards

[Dick Rector]

I would NEVER use an oil-based cleaner like WD40 as it will end the keyboard forever. It dissolves the rubber contactstrips and make them sticky. Qtip and cleaning alcohol is the best way and be VERY VERY careful doing it. But the problem does sound like the rubber contactstrips underneath, a common problem with older keyboards. I have replaced them over the years in various keyboards and it is only a temporary solution.

[geobee]

Hi all, retired tech here. Yes, it will be the silicon contacts worn away. I have repaired many of these contacts over my working life, not only in keyboards, but remote control hand pieces also. You can use alcohol based cleaners yes, never WD40, but the proper fix is to buy a little syringe of silver conductive paint, very cheap off Ebay, around $2.00 AUD that is used for this purpose.
. Wont last forever, but will get a bit more use from it. While you are at it, clean all the carbon pads on the board strip also. Best to use a cleaner that is used for pots (volume controls). Just spray a little on a cotton bud and go over the pads. Just dab a little bit of the paint on each of the worn silicon pad tips and the jobs done. This is a much cheaper fix than replacing the whole silicon strip with a new one, and for an older keyboard, it is far more economical. Good luck with it.

[MarkF_48]

I would not attempt to clean contacts at this point, but rather first disconnect and reseat the cabling connectors that connect the keyboard circuit boards back to the main board. The issue is the D and G# notes over each octave. These notes are common through the entire octaves of the keyboard through a diode matrix back to the connector CN1. If one of the pins through the connector CN1 is making poor or no contact it's very possible velocity will not be sensed correctly. Each key has two contacts. When a key is struck one contact makes an initial closure which is 'Note On'. The second contact follows and depending on the velocity to which the key is struck determines the delay time from when the first contact had initiated the 'Note On'. The longer the delay, the softer the note will sound. The shorter the delay, the louder the note will sound. If a main data line from second contact of the D and G# notes is compromised there's a pretty good chance velocity may not work on those keys.
If not the CN1 connector being an issue, there are some capacitors and resistors in in the data lines that address the CPU from the keyboard diode matrix. If one of these components has a problem it may be beyond the scope of what the OP is capable of repairing, particularly if they are 'surface mount devices' (SMD).


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[geobee]

Mark, the only issue with that is, if the OP is not electronically minded/experienced, it is easy to damage those push in wire connector plugs, bend any of the wires while inserting, and very easy to come unstuck for a novice. I hear what you are saying, but unlikely it would be a connection issue there as there is no heat involved, as with say, an LCD tv set, where those type of connections do often play up. Best for the OP to do the silicon strip fix first, then if no joy, it will be a tech job to fix, but then the cost would kill the value of such a basic instrument.

[Jean-Pierre 33]

Hello everyone,

Many apologies, I meant Kontakt Chemie's Kontakt 60 or any product intended to clean the electrical contacts and the potentiometer tracks.

Best regards

[MarkF_48]

Mark, the only issue with that is, if the OP is not electronically minded/experienced, it is easy to damage those push in wire connector plugs, bend any of the wires while inserting, and very easy to come unstuck for a novice. I hear what you are saying, but unlikely it would be a connection issue there as there is no heat involved, as with say, an LCD tv set, where those type of connections do often play up. Best for the OP to do the silicon strip fix first, then if no joy, it will be a tech job to fix, but then the cost would kill the value of such a basic instrument.

I've been doing electronics repair, both in a professional capacity and as a hobbyist for better than 50 years and I'll stand behind what I said. From the symptoms the OP had stated this is not a problem with the silicone rubber contact strip and its removal would be a waste of time to remove it. A keyed header block is mounted on the circuit board which mates to a corresponding female connection block on the cable. If the OP is capable of disassembly of the keybed far enough to access the rubber strips, he's then exposed the cable header connections to the cable in question. Removing and then reseating the connector from the PCB header is no more electronic than removal of the rubber strip. It's up to the OP's judgement whether he wants to attempt what I had suggested. As I had stated it possibly could be the network of resistors or caps further along in the circuit and that indeed would be beyond the OP's skills to troubleshoot or fix. If the OP has built or upgraded components in a computer he likely may be able to attempt this. A repair in a shop would not be worth the cost and better to purchase a new keyboard.

[AnupamEnosh]

It's up to the OP's judgement whether he wants to attempt what I had suggested. As I had stated it possibly could be the network of resistors or caps further along in the circuit and that indeed would be beyond the OP's skills to troubleshoot or fix. If the OP has built or upgraded components in a computer he likely may be able to attempt this. A repair in a shop would not be worth the cost and better to purchase a new keyboard.

Well, that is exactly what I was expecting to be the outcome. Probably I need to get a new or second hand keyboard.