[sdiy] SL880 Pro problems

[Mike Bryant]

Have you tried another external 9V PSU ?

If that fails, put a multimeter on the power supply regulator inside and see if it outputs a sensible value (5V).

After that my guess is the MIDI circuit has been honking all these years and somehow the volume pedal has been calming things down.   You'll need a scope to check that.

Great keyboard - one of the best - so definitely worth repairing.  Where are you (roughly) ?


-----Original Message-----
From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of Mike Kelly
Sent: 06 November 2021 21:04
To: synth-diy
Subject: [sdiy] SL880 Pro problems

Hi, I wondered if anyone has experience in troubleshooting Studiologic SL880 midi keyboards. I picked up this one second hand and really like the weighted action.
Since the off there has been a problem with some rogue midi output signals. Plugging a volume pedal into the volume socket seemed to solve it. Now however after a couple of years of use I am getting random and unstable outputs and it’s unusable. I tried changing a couple of the electrolytic caps as I had spares. The board generally looks OK and the settings functionality and the LEDs all seem to be working fine, so I think there’s not much wrong with it. If anyone knows a likely point of failure on these boards please give me a shout. 

I thought about replacing the crystal as it looks a bit aged. Marking is 24.0MHz, HCJ-30 02-02-57. Would any 24MHz crystal do? Or am I on the wrong track.

Alternatively if there’s a way to put a whole new DIY circuit in there I could go that route. They’re Fatar keys I believe, with aftertouch.

Thanks.
M
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