[sdiy] SL880 Pro problems

[MTG]

Curious how this matches the initial query. Different symptoms, but ...

http://fixingelectronics.blogspot.com/2012/11/fatar-sl-880-repair-replacing-crystal.html


On 11/7/2021 8:23 AM, Mike Bryant via Synth-diy wrote:
> 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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> 
> 
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