I wish to know how to open a Roland JUNO-D synth to access the little rubber strips with the key contacts; I have the typical key-not-sounding problem.

https://www.roland.com/uk/products/juno-ds/
https://www.sweetwater.com/store/detail/JunoDS61--roland-juno-ds61-61-key-synthesizer/reviews
https://www.sweetwater.com/store/detail/JunoDS61--roland-juno-ds61-61-key-synthesizer/reviews
https://www.rolandus.com/blog/tag/juno-di/
https://www.amazon.com/Roland-Lightweight-Weighted-action-Keyboard-JUNO-DS61/dp/B016NUAL5Y

Sir errar 1 problem is my keyboard how to repair it's a Juno g keyboard error 1?

You install the expansion card to the bottom side of the Juno by removing screws. For detailed step by step instructions, I suggest that you refer to page 174 from the manual that you can download from: JUNO-G Owners Manual (JUNO-G_OM.pdf)

The key contacts have become contaminated. Disaasemble and find the contacts under silicone rubber domes. They are typically black conductive rubber pills, two per key. Clean them and the circuit traces they press against under them with ONLY 99% isoprophyl alcohol and Q Tips GENTLY. Then reassemble and test operation.

The key contacts need to be cleaned. They are usually conductive rubber pills in silicone domes that get pressed onto circuitboard traces by the keys. Disassemble to get at the contacts. clean ONLY with 99% isoprophyl alocohol and Q tips. Clean both the pills AND the circuit traces they contact.

Be very careful of cables when opening the unit. Document where all the screws go and their length and threads.

I would recommend taking it in to be repaired. If they service Roland products they will have access to any parts it needs. It sounds like the key contacts are damaged or dirty. In either case it is not easy to disassemble the Juno because of the internal wiring. It needs to be reassembled perfectly for it to work properly and it is easy to damage something during disassembly. Hope this helps.

Not sure what you mean by "buttons". IF you are trying to change voices, a lag between sounding of the old and new voice can be expected as the generators within the synth are reconfigured for the new voice. This is a lower-end synth and as a result doesn't haved the performance of some of the newer ones.

If the lag is just between notes that are being keyed using the same voice, that is too much delay and something is probably set wrong.

Simple way is MIDI out from Juno to MIDI in on MPC, then (depending on how you want to work), connect MIDI out from MPC to the in on the Juno. If you do this you MUST turn local control off on the Juno or else you'll get double triggers (internal + msg in from MPC). Now to record sequences on MPC , set MIDI to as track in setup window (on the 2500, this is accessed by pressing MODE then pad 9, then press button under the corresponding tab [on LCD]) then set your MIDI channel by port, meaning if your MIDI cable is physically connected to out A, in your LCD in bottom right corner it will show as follows: 1A. This indicates you are transmitting on MIDI channel 1; port A. Remember, MIDI IS NOT AUDIO!!!!! Since the Juno is a synth and not a workstation, all transport controls are handled by the MPC, that's pretty much it... Hope this helps a little, enjoy!

P.S. Go to mpc-forum.com its THE sh**! They also have links for their e-book I have one for the 2500 and its awesome!!!

Normally you have to clean the conductive rubber "pills" AND the circuit board traces they get pressed down on.

USE ONLY 99% isoprophyl alcohol on Q-Tips to do the cleaning and be gentle.

Use of other product like deoxit and other contact cleaners will wreck the contact material.

The problem of the Juno-D is de rubber strips inside under the keysthere are 5 strips, you have to clean this rubber strips with alcohol and clean the board too, this will resolve your problem if you leave the Juno-D without playing for a long period you will get the same problem again. this is a very poor keyboard it,s a pitty that Roland Make so poor keyboard!!!!