Some keys on mpk49 do not play unless hit hard

There is a dual contact strip under the keys that the hammer (key) hits from the hinge end. When the hammer hits, the time it takes to close both contacts determines the level of pressure and gives a quiet, (light) or loud (hard) and the processor knows how loud to reproduce the note/s.
If a contact is damaged, there will be no control of the volume.
Replace the conract strip and felt pad.

Water/ moisture damage corrosion of electronic connections or power supply cooked certain chips on motherboeard maybe melted after heating up to much

Check your cables - I've had similar problems with various amps playing various guitars; the guitar electronics and the amp electronics are fine, but the cable is damaged internally and this causes the same problems as you have described. Have you tried using a different cable? Buy a different one, try it out, and see if you have the same problem. If you have a friend who plays, let them plug their cable and guitar in the amp - if it works, your faulty cable is the issue. Hope that helps!

I'm not familiar with Reason 5, but many midi track recorders need each instrument assigned to different midi chanels to be heard back. Check the manual in how to assign the midi tracks. Also, the playback has to be through a unit that is multi timbrel capable. Good luck!

Using keys too "hard"? If you are hitting them so hard it MAY rattle the circuit board inside and momentarily break a connection that is causing the processor to stall. This is not a good idea... Keys do NOT have to be played hard... If you are doing this as a show off thing, be prepared to pay repair bills. You can show off without putting much force on the keys. You will likely damage the aftertouch sensor by beating on the keys and also crack the circuitry that the key contacts work against requiring expensive replacement.

Thisis hard to troubleshoot... The keyboard insynths are usually scanned as a matrix... If a disconnect diode has failed, then wrong notes can be triggered. There is USUALLY rows of the diodes on the circuit board where the keys hit. There are usually TWO contacts per key in order to sense key velocity. The lkey contacts are usually conductive rubber pills pressed against circuit traces under the keys. One sometimes needs to clean these contacts using 99% isoprophyl alcohol and Q tips.
I would do further testing of ALL combinations of notes played together to see if possibly any others show up as that could point to a particular failure.

Most of these use conductive rubber pills that are pressed onto circuit board traces by the keys.

Clean the board AND the pills with 99% isoprophyl alcohol and QTips.

Have a look in your manual at the sections on Note Repeat and Time Division.NOTE REPEAT] – Holding this button while
striking a pad causes the pad to retrigger at a
rate based on the current Tempo and Time
Division settings. The Note Repeat feature can
be synced to an internal or external MIDI Clock
source. [NOTE REPEAT] can function as a
latching or momentary button
19. [TIME DIVISION] – This button is used to specify
the rate of the Note Repeat and Arpeggiator
features. When [TIME DIVISION] is activated,
you can press one of the 8 switches to specify a
time division. [TIME DIVISION] can function as a
momentary or toggle button.
Please note that while [TIME DIVISION] is active,
the 8 assignable buttons will not function as MIDI
CC or Program Change switches until [TIME
DIVISION] has been de-activated.
20. [ARP ON/OFF] – This button enables and The manuals and updates can be downloaded here:http://www.akaipro.com/mpk49 Please let me know if this helps.

USUALLY the keys are matrixed in groups of 8 starting at a "C".

Each key USUALLY has two contacts. The differential time between the contacts closing is measured as "velocity" which is used to control the amplitude of the sound. The matrixing of the keys may be done in any of several ways but usually the bank busses are driven and the keys outputs are merged with diodes. You really need a schematic and Yamaha will usually supply the service manuals on CD for about $15.

If conductive rubber contactss are used, those should be cleaned with 99% isoprophyl alcohol. DO NOT USE CONTACT CLEANER !!!!!

Also clean the traces the contacts contact.

When a bank of the 8 keys are dead, you MAY have a broken trace on the coircuit board or a broken cable wire. Be careful inremoving ribbon cables as the end wires are pulled from the contacts unless the pull is distributed across the cable.

Is it a dynamics sensing keyboard (does it sound soft when you play softly and loud when you hit the keys hard)?

If so, you need to clean the double contact under those keys that sound too loud (if contacts are dirty, the key might either not work at all or it may loose the ability to sense how hard you hit it and will work at full volume).

You'l probably need to disassemble the unit and remove the keyboard to be able to remove the keys that don't work well, after you've done so, you need to clean the lower (under) side of the double rubber button which is struck by the key when you hit it, also be sure to clean the contact tabs on the circuit board undereath the rubber pad (you can use ethyl or isopropyl alcohol and "cotton sticks").

This should do the trick if the contacts are dirty, but it may have no effect if they are damaged or worn out (in such case you would have to replace the rubber pad for that particular key).

regards

3rq8 (Triarcuate)