K2600X Repair
Sal,
First off, note that the following instructions are in reference to dealing with a K2600X hammer-action keyboard. That being said, the steps you will need to follow should be more-or-less the same, with possibly a few minor differences (I have not serviced a K2600S).
You need to remove the keybed and clean the key contacts to resolve the 127 velocity (loud key) error. The key is sending false triggers due to some type of dirt or debris under one of the key contacts. First, follow the directions in this thread to take the keyboard apart (remove the screws on the bottom FIRST. You will know which screws to remove because they run right down the center, and have one empty hole on each side. Some screws may or may not be in the center hole. Kurzweil designed their machines this way because users may frequently need access to the inside of their boards for upgrades, maintenance, etc. Doing so may strip out the aluminum structure to which these screws thread in to, so they added extra holes for your convenience. Then, remove the endcaps [all screws closest to the ends, including the ones on bottom - do the bottom screws while you're removing the midrail screws]. Then, flip your board over and remove the back screws).
Now, this next part is trick and it actually helps to have your instrument on a keyboard X-stand or similar because you need to access the bottom again, but the keyboard HAS to be right side up, otherwise the action could fall or shift and become damaged/damage something. A solution I thought of was to place an X-stand in front of a computer desk with a towel spread out on top. The control panel will lie upside-down on this towel while your keyboard remains upright on the stand. Using this approach, you will not need to flip your keyboard over in Step 1. The screws you are about to remove are the action screws. There will be a row near the front of the keyboard, as well as a row 6-8" back, directly in front of the midrail screws (though not directly corresponding).
Once you get these screws out, the keybed should lift out. Take caution -- there are several cables attached to the keybed. Two are for aftertouch (one for sharps and one for naturals). These plug in under the pitch/mod wheels. There is another larger ribbon cable which connects to the sensor board under the action. Some of these cables may be held in place with clear tape. Carefully remove this tape and unplug the connectors. Take note of where the connectors plug in -- especially the aftertouch connectors.
Your action should now be free. To work on the key sensors, lay the action face down on a padded surface. Underneath, you will see two long circuit boards (end-to-end and joined by a short ribbon cable). You may remove both boards and clean all the sensors, or remove only the board under the problem key. If you remove only one board, carefully unplug the interconnecting ribbon cable.
On the opposite side of this PC board, there is a series of gray rubber buttons. There are actually two buttons for each key (One high velocity and one low velocity). Remove the rubber strip corresponding to the problem key by simply pulling on it gently. It is held in place using small rubber studs which press through holes in the PC board. Each section of rubber strip will be about 6-8" long. Under the rubber strip will be a series of black contacts. You need to clean these contacts gently using a small amount of rubbing alcohol on the end of a Q-tip.Take care not to scrub the contact too roughly or you may damage the carbon in the contact. Remove any dust or debris you may see. Next, inspect the underside of the rubber strip. You will see two black contacts under each "bubble". These should be free of debris and damage as well. Clean the contacts on the strip as described for the PC board. If you find any damage, you can order the parts online. They are fairly standard and inexpensive (specify your make/model).
To reattach the rubber contact strip to the PC board, carefully lay it over the contacts and line the holes up with the rubber connecting studs. Use a toothpick or other small poking tool to push the studs back in to their holes from above (take care to get them all, as any gaps could allow debris to enter). Now, follow the disassembly in reverse order.
To address your key clicking issue, you will need to have the action upright. The action will need to be removed for this step as well, as the key needs to come forward a bit to release from the catch.
To remove a key, first, disconnect the small spring at the rear of the key using needle-nose pliers. There will be a notch at the top-end of the key containing a plastic tab. This hook will be about the same width of the notch it is in, and it should be a slightly different color than the key itself (some models were blue, some green, and others more of a natural plastic color - as I believe is the case for the K2600). Take a small slotted screw driver and place it in this notch parallel with this tab. The screwdriver should be on the side of the tab nearest the front of the keyboard. Gently turn the screwdriver so that it begins to push the tab towards the rear of the key. While doing this, place the index finger of your free hand under the rear end of the key (where the spring attached) and lift. When you have pushed the tab far enough, the back of the key will be released. To remove the rest of the key, pull it slightly down and toward the front of the instrument. The front of the key will become unhooked and the key is now free.
You will see two lines of black felt under the key. The felt near the front dampens the white keys, while the felt toward the rear of the key dampens the black keys. This felt can get compressed enough to cause noise. The issue most likely needs to be corrected by ordering new felts, but it may be possible to simply "fluff up" the felt. Note that this is most likely a temporary fix, as the felt will soon become re-compressed.
The felt strips run the entire length of the keyboard, so replacement will require the removal of several (or all) keys. The felt is held in place using an adhesive -- the felts likely have a "peel-and-stick" backing. Be careful when removing the felts so as to not damage the aftertouch strip residing underneath. Contact a Kurzweil dealer for the exact felts you need. Using the wrong felts may interfere with velocity readings (i.e. too thin of felts will cause unusually high velocities, and felts too this will prevent your keyboard from reaching full velocity [127]).
Hope this helps! Contact me at lesthelightinguy at yahoo.com if you need any further assistance!
I would attach photos of the sensors, disassembly procedures, etc but I am new, so the forum won't let me. For anyone interested in these pics (for visual reference only); please email me.
