Post your views and questions about the Akai MPC2500
By bankshotmusic Mon Jan 13, 2020 3:35 pm
Hi everyone,

First time poster but have learnt and benefited quite a lot from reading posts in this forum over the years.
I have an issue with my mpc 2500 that I am struggling to find the answer to, and everyone I have asked seem puzzled by it also.

The UP and RIGHT cursor buttons are unresponsive, my first move was to replace the tacts like I usually would, though this didn’t work out. The tacts are the right model and all that, I made sure to check.
This is an issue that just effects the UP and RIGHT, the DOWN and LEFT work great.

Before I replaced the tacts the up and right buttons both became more and more unresponsive over time. Sometimes requiring a particular direction to process the input until finally having no response.

I had replaced all four of the cursor button tacts once in the past with no issues.

I’ve had some friends who are more electronically inclined look over the wiring and test currents with a multi meter and things all seem to be in working order. This problem seems to have everyone I ask stumped. Haven’t found any other people online with the same issues, they all seem to be resolved by replacing the tacts.

Any ideas? I miss my baby...it’s amazing how annoying two unresponsive buttons can be on these old beasts.

Thanks!!
By Sense-A Sun Jan 19, 2020 12:42 am
Page 22 of the service manual has a schematic for the board with the up and right arrow keys.

https://www.mpc-tutor.com/files/mpc-ser ... Manual.pdf

Look at the trace labeled KR3 towards the middle of the page. The up and right cursor arrows are at the end of the trace. My best guess is that the trace is scratched between where the up and left cursor arrows tie into the trace. If the left arrow, tap tempo, and mode buttons still work, then there must be a scratch in the trace.

Check the trace for continuity with a multimeter. And visually inspect it. You could have scratched the trace while repairing the other buttons. Or if you have a cheap solder iron it may have transferred too much heat and lifted the trace a little bit.

Bad trace on the circuit board? First and best guess
Bad cable connector? Less likely
A batch of faulty tact switches or wrong polarity or wrong spec? possible unless you can rule this out

Any other pads or buttons not responding?