[sdiy] SL880 Pro problems

[Mike Bryant]

Does the PCB look something like this
https://www.fullcompass.com/prod/276916-studiologic-41911550-main-pcb-assembly-for-sl-880

If so try unseating the main IC, cleaning all its contacts and those of the socket, then reseating it.

-----Original Message-----
From: Michael Kelly [mailto:mike at downlode.uk.net] 
Sent: 07 November 2021 11:19
To: Mike Bryant
Subject: Re: [sdiy] SL880 Pro problems

Hi Mike,

I tried another PSU with the same results. I put a scope on the voltage regulator and it is outputting a steady 5V.

There’s definitely an issue with the volume pedal input but putting a jack in the socket stops those Volume MIDI messages, so there is some new problem which has developed here…

I’m London based so perhaps there is someone nearby who knows these units. As I bought it for £60 I can’t complain about the service its given me!

Bw,
M

> On 7 Nov 2021, at 00:00, Mike Bryant <mbryant at futurehorizons.com> wrote:
> 
> 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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