Ensoniq KT-88 malfunctioning

Hello, all;

I have a KT-88 purchased in 1995 that was until quite recently still working perfectly, both the internal synth and all the MIDI in-out-thru stuff. The only issue it has ever had was the battery warning in 2014; I had the battery replaced while living in Austin TX at Switched On for $100 parts and labor (pretty reasonable I thought).

It sat for a couple of months recently without being turned on while I replaced and reconfigured the two desktop computers (one Windows, one Linux) that comprise my home studio along with five other old hardware synths, and when I turned it on a couple of days ago, it produced (when keys are pressed) a very low volume sound somewhere in between one of the string and one of the brass presets. (FWIW, having the volume slider at full high or full low makes no difference in this very low volume sound.) I tried the reset and everything seemed to be back to normal, except for a weird fast “echo” effect on the default patch (“E-Prime Grand” or whatever it is called) and every other patch I tried. At the time, I thought it might be something that I needed to look at in the MIDI setup, that one of the other synths was on and there was some kind of weird MIDI artifact happening. I was pressed for time so I played for a few minutes to satisfy myself that the KT was okay, then powered it off.

Yesterday, I powered it up again to troubleshoot the “echo” and it was making the same very low volume stringy/brassy sound again. This time, multiple resets didn’t solve the problem, but powering it off and back on several time resulted in my getting a piano sound again, but once more with the “echo,” although I made sure that the echo was just happening with the KT by unplugging the cable from its MIDI Out.

Is this information that might help anyone guess what might need repair in the KT? Has anyone experienced something similar with a KT in the past? If it will help anyone take a guess, I’ll try to get a recording of the “echo” for people to listen to.

Thank you!

Most likely a failed Tantalum capacitor. They fail in either a short circuit without visible trace, or explode in flames.

Since its 1995 the electrolytic capacitors have also timed out. You need to start with the power supply and check everything for functionality. Any Rifa caps must be changed. After the power supply, then work on the motherboard, looking for and replacing the tantalum capacitors.

If the power supply gets too far out of spec it can damage the precious replaceable sound generation chips.

Thank you for the reply, @midnightvisions. I don’t have the proper setup (bench, equipment, skillset ) to do this but I’m also not ready to give up on this workhorse that has served me so well.

I’m going to try to find a tech willing to take a look at this. If anyone has any recommendations of a tech or repair facility in North Carolina, please share! I’m in Winston-Salem, but Charlotte is only 1 hr 15 min south and Raleigh-Durham 1 hr 45 min southeast.

ADDED: I’d rather not ship this beast anywhere as it weighs a ton.

I have some amp volume issues on my KT76. I’m in Charlotte also looking for some competent folks. Please let me know if you find someone. Thx