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Controlling SAMS Help Needed

Building organ consoles for use with Hauptwerk, adding MIDI to existing consoles, obtaining parts, ...
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Re: Controlling SAMS Help Needed

PostWed Feb 09, 2022 9:47 pm

Hey folks.

Just wanted to report back.

I made several sweeping changes, with massively improved results.

1.) No daisy chaining. There are two ENCODERS and two DECODERS, each with their own dedicated MIDI port on the interface. This was a huge help. Version one (in the video) had the two ENCODERS daisy chained on one MIDI input, and the two DECODERS daisy chained on one output. A couple of days ago I put the two DECODERS on their own OUTPUT and that helped a lot, and today I did the same with the ENCODERS. This made the SAMs behave like they are supposed to (save for a couple of anomalies that I still need to address.)

2.) I spoke to Bob Arndt who mentioned to me that the old Rodgers (Syndyne) SAMs, to his recollection, used to have one brass leg on the reed-switch, rather than steel. When he said this, I realized, he was in fact correct, as I had noticed this on my SAMs. Each one had the original reed switch leg(s) cut off, and were soldered instead to a brass wire coming through the PCB. Brass is not magnetic, so therefore it is less prone to interference from the solenoids and magnets. This got me to thinking, and I was able to go around and check on a few of the reed switches, and indeed some of them had been replaced over the years - a couple of them by me recently, and I had just removed the brass leg altogether thinking it wasn't necessary - and now I will be redoing these. I also realized, that the "fluttering" in the video stopped as soon as the coils were no longer energized, confirming that the solenoids were interfering with the reed switches. So in addition to the above, I also shortened the pulse timing on the mddp128 boards.

3.) I also found one bad solder joint (my error) that was shorting the solenoid ON with the reed switch output.

4.) I also ordered a 100amp power supply to replace the 55amp power supply but it hasn't arrived yet, and as it turns out, I don't think I need it.

So, for the moment, I feel pretty confident in saying things are looking good.

Drew A. Worthen
Master of Music in Composition - Butler University
Director of Music & Website Admin - Greenwood UMC
Design Engineer - American Sound and Electronics - Indy
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Re: Controlling SAMS Help Needed

PostThu Feb 10, 2022 4:40 am

Excellent. Thanks, Drew.
Best regards, Martin.
Hauptwerk software designer/developer, Milan Digital Audio.



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Re: Controlling SAMS Help Needed

PostFri Feb 25, 2022 9:36 pm

I well recall the summer during the 1980s I spent wiring up the console for a large theatre organ (256 SAMs). We decided to use a deep cycle marine battery with a trickle charger to power the SAMs, with power to spare. It also had the benefit of keeping the volatile combination action memory powered during a power failure. But it was necessary to top up the battery occasionally.

But that was then and this is now. With high current switching power supplies being readily available and relatively cheap, there is no need to consider using a battery.

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