Roland S-50 Static Output

[Ricoche]

I have a question about a newly acquired Roland S-50 Sampler that I got for free from a used shop here in Japan.  Everything works on it perfectly except there is an issue that I can't isolate so I'm thinking of replacing the boards inside but I'm not sure which one yet.  If I could just replace one and not all, I could likely fix this for just $50 bucks or less.

Here are the symptoms.

1.  I am getting static output across all outputs at 50% or higher in volume.  You can listen here to the static when a sample is played back.
http://jimatwood.net/synth/Roland-S50-Static-Output.WMA

2.  I noticed also that when the first 8 notes are play the volume is at normal levels, but when I play the next 8 notes it drops to about half.  Then the next 8 notes played produces normal volume levels and so on.  It's almost like a bad chip on the 106 when you play 5 notes and the fifth is messed up.  However, the static issue still is present on all notes regardless of volume level.  ( Polyphony is 16 on the S-50 )

3.  Not a problem hopefully, but I noticed a black resin wrapped IC Chip on the CPU Board labeled MD6209.  The S-50 was released in 1986 so I hope that one chip isn't any sort of problem chip like on the Juno.  It does however look like a hybrid of sorts that is protect by the black wrapping identical to the 106.  Interesting I thought.

What I've done so far:

1.  Removed and cleaned the volume sliders with Deoxit although I am not sure if that did anything.

2.  Removed all boards and checked for solder cracks, blown caps, or anything out of the ordinary.  Nothing found at a glance.

So, I'm thinking of replacing one or all of the following boards:

Output Jack Board
Volume Slider Board
CPU Board
Power Supply Board

( I got the S-50 in mint cosmetic condition for Free.  The LCD, all keys, and Floppy Drive works 100% .  Total cost to replace all boards above with shipping to Japan is $185.00, so basically it's like buying an S-50 for $185 unless I only need to replace one board which would reduce the price.  Is it worth it?  Not sure yet...laugh. )

Thus I'm curious which board or boards I should replace  Any thoughts from any experienced techs?

Thanks very much!

Jim

[noiseybeast]

The demo audio doesn't work.

[Circuitbenders]

demo works fine for me.

I think what you have to consider here is that its possible it'd cost you more to replace ANY individual board in an S50, than it would to just buy another S50! At least in the UK it is.

From the randomness of the noise on that demo i'd say that its most probably a hardware fault such as a connector ribbon, fader or socket somewhere, but god knows where. Does the S50 have switching sockets anywhere? If so that could be the issue. Is there any way to tap into the audio signal before it gets to the output jacks board?

Try bypassing the volume fader so its permanently set to maximum and see if that sorts it out.

[noiseybeast]

That sounds like a distortion more than a static.  Don't know if that helps.