[sdiy] Fwd: SL880 Pro problems

[Mike Kelly]

Oops I haven’t been copying emails to the list when answering people.

> Begin forwarded message:
> 
> From: Michael Kelly <mike at downlode.uk.net>
> Subject: Re: [sdiy] SL880 Pro problems
> Date: 7 November 2021 at 17:19:34 GMT
> To: Mike Bryant <mbryant at futurehorizons.com>
> 
> Yes, almost exactly the same. A couple of the polarised caps are different, they look like tantalum ones where I have aluminium barrel types, as in the images in your other post.
> I will try cleaning up the IC. I’ve been reflowing some cold looking connections, but it doesn’t seem to have done anything.
> 
> Looking at the midi log, what’s happening is a strange sort of buffering - if I press key A2 multiple times, then G2 multiple times, A2 will continue to be sent for say 30 note events while I am hitting the G2 key before eventually G2 is sent. So output is not random but backed up.
> 
> 
> 
>> On 7 Nov 2021, at 16:23, Mike Bryant <mbryant at futurehorizons.com> 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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