SY35 with an unusual audio interferance. - solved

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Rara
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SY35 with an unusual audio interferance. - solved

Unread post by Rara »

Hi all,

This is a small minor problem I have had with my SY35 for as long as I have had it,
that is radio interference.
Only my sy35 suffers this and only during the colder months, usually May through to end of august.

I have been puzzled over this for a long time.

I can quite easily listen to ABC radio national Australia (AM 729 Khz) with my headphones on.

At first I thought this was being picked up by my mixer because of all the cables hanging out of it being a
great antennae. I turned all my other synths on, I muted all the channels. One by one I unmuted them, listening for radio.
As i said only the sy35. If I turn up the gain on that channel I can sit there all night
comfortably listening to the radio either through head phones or main speakers, with a fair amount of other background radio noise.

I checked all of the cables for loose sockets/fits, checked for broken joints in the plugs, checked
power cables even to the point of separating audio from mains as much as possible and if mains had to go over audio
i did so as close to 90 degrees as I could.

This seems to be more prevalent after a decent or heavy rain.

SY35 is externally DC powered so it can't possibly pick up anything through earth as it is double insulated.
I know devices are supposed to accept RF interference, a specific frequency is puzzling though.
I'll try get a recording of it one day. :-)

Has anyone have any ideas?

Rara 0-)



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Re: SY35 with an unusual audio interferance.

Unread post by Miks »

Hmmm - that's really strange 8O

Have you tried to operate the synth with only it's DC psu and a headphone plugged in? No other pedal(s) or other cabel (i.e. outputs) connected? If so - can you still listen to that radio station?

Try to change the position of the synth - move it around in an angle of 90 degrees horizontally - does this change anything?

How about taking the SY to a different room - eventually up- or downstairs - does that make any difference?
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Re: SY35 with an unusual audio interferance.

Unread post by parametric »

Rara -

Only thing I can think of is the PSU itself? I'm guessing it's a "Wall-Wart with a thin twin cable and one of those coax power conectors?

Try a different PSU - if you can . . . perhaps your PSU is duff in some way? - so the power lead is acting as an aerial?

As you say - double-insulated should be free of such problems . . .

Are there any unconnected wires inside the 35? I can't recall if the case is pressed metal or plastic.

One synth I had once, had an earthing cable screwed to the case inside . . . . the other end, supposed to be attached by a self tapper

to a pad on the corner of one of the pcbs . . . . . . . it wasn't. The screw was missing - so it was just floating . . . . .

So, a bad internal earth . . . . .

just a thought

parametric
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Re: SY35 with an unusual audio interferance.

Unread post by Rara »

thanks :-)

it is a strange problem

I have reduced some noise by rearranging the power cords on the power board :think: odd ....
SY35s PSU has a coax type power cord (tip +ve) with the typical barrel connector.

I'll take the cover of the sy35 and check grounds in there ...

a broken ground seems to be a more likely issue (if i can find it)
it doesn't explain how the interference becomes more noticeable in bad weather.

Rara 0-)

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Re: SY35 with an unusual audio interferance.

Unread post by parametric »

Rara wrote:
Sat Mar 07, 2020 3:07 am
it doesn't explain how the interference becomes more noticeable in bad weather.
Rara 0-)
Indeed it doesn't . . . . :? That is a mystery to me . . . .

We had an SY22 at Uni as floating General Purpose Synth that the Students used to use . . . similar PSU to yours I guess . . .

NEVER gave any such problems . . . . :roll:

Hope you track it down . . . it really is SO annoying . . . . and ought NOT to be happening . . . .

Chris
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Re: SY35 with an unusual audio interferance.

Unread post by Zed »

I'm not at all surprised to hear that bad weather affects it. Back when all the TV broadcasts here were analog, we'd always check for stations we normally couldn't pull in under more pleasant conditions, and radio stations...particularly in the AM band...would make TREMENDOUS jumps, even allowing us to listen to radio from the other side of the world, on occasion. I realize this probably isn't very helpful, but to me, it would suggest that you're on the right track in looking for things that might be (mis)functioning as antennae...

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Re: SY35 with an unusual audio interferance.

Unread post by Rara »

There has been some progress with this.
there was a crack in ground joint (again) from one of the line outs on the synth.
(while I think of it off topic .. why are audio outs not supported like this picture attached. (rear of an MKB200) )
I think there are multiple sources of noise now ...
20200418_171855b.jpg
20200418_171855b.jpg (37.81 KiB) Viewed 532 times

I rearranged the room and the am radio interference has changed. which led me to another
source of noise. without being exact in my measurements my rack was facing roughly north when
I first had this problem, now the rack is in the corner facing northeast. i can no longer listen to the radio
station i was picking up, now its general noise. cut a story short,
the majority of noise is coming from the effects processor, (i think) my mixer has broken
joints on a few pots (thanks cat :lol: ) which some happen to be the channels the SY35 was on.
Mixer connected to effects processor with the sends and returns.

The keyboard is on a rack at the top so there is nearly 6 feet of audio cable going up the side of of the rack
with 3 other keyboards below it, so if anything was a big antennae those cables were it.
it looks to be mostly from the mixer and effects processor being the sources of noise now.

Rara 0-)

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Re: SY35 with an unusual audio interferance. - solved

Unread post by Rara »

I am happy to report the interference has been sorted.

Some of the noise came from the SY35 having a broken ground.
At first I thought the SY35 was the problem and nothing else.
The rest of the noise was coming mostly from the mixer and the
effects processor hooked up to it.
Having the effects on made the noise worse.

I dismantled the mixer and cleaned everything checked for cold
joints on all the boards. There were non found anywhere. The only thing I can think
of the board underneath which all the channel boards attach to had some oxidation
in the sockets. they where cleaned also and a tiny pet spider living in the mixer was relocated.

This has taken care of both EM and RF noise. :)

Rara 0-)

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Re: SY35 with an unusual audio interferance. - solved

Unread post by parametric »

Darn! . . . . who'd have thought it :lol:

I would have thought that the inside of a mixer is NOT the first location I'd consider to be Fly-Blown :o

Still . . . . it IS Dark, and it IS warm (sometimes) . . . and , just maybe - he's a Music Lover? :think:

Chris
Alesis Fusion 8SSD AND 6SSD - BOTH are 384Mb/120Gb SSD/Akai ADVANCE61/Yamaha MOXF6/1024Mb Flash Ram/Yamaha SY85/8.5mb vol/1024k non-vol/DX21/Roland MT32/Bachmann double overstrung Baby Grand Piano/Win10 Pro/Ubuntu MATE 15.0.4/iBook G4/Mac OS 10.4.6/ProTools 7.4/MBox2/M-Audio MicroTrack 24/96

NI Komplete11 Ultimate

Sector101 2x SYEMB06 / 4 x EXM-E3 128MB DRAM Module

BRAND NEW DSDD (720k) FLOPPY DISKS FOR SALE - http://www.yamahaforums.co.uk/forum/vie ... =22&t=9217

Watch out now! take care, BEWARE of the greedy leaders! They'll take you where you should not go - (George Harrison)

IT'S TRUE - "MONEY TALKS" - TO ME, IT MOSTLY SAYS "GOODBYE" ;-)
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Re: SY35 with an unusual audio interferance. - solved

Unread post by puremusic »

lol
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