Patches and discussion for Ensoniq VFX family

-----Original Message-----
From: tijgersanni <m.c.breukink@...>
To: Ensoniq-VFX-SD@yahoogroups.com
Sent: Sun, 5 Oct 2008 1:44 pm
Subject: [Ensoniq-VFX-SD] SD-1 32 analog values problem









A short time ago the display of my SD-1 32 showed something like

"battery voltage low". Also it was out of tune and all the voice have

LFO modulation (even if the modulation wheel is at the lowest

position). So I replaced the battery (I am a technician) But it didn't

solve the problem. I checked all the analog values through the

testpage and they are all wrong (about twice as low as they should

be). I now am suspecting the circuit around the 4051 and opamp ; this

circuit collectes the analog values and transfers them to the A/D

converter inside a Processorchip.

Has anybody had the same problem ?



Greetings from Michel



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-----Original Message-----
From: soundthinker2001 <roger17@...>
To: Ensoniq-VFX-SD@yahoogroups.com
Sent: Sun, 12 Oct 2008 2:48 am
Subject: [Ensoniq-VFX-SD] Re: SD-1 32 analog values problem

























--- In Ensoniq-VFX-SD@yahoogroups.com, "tijgersanni"

<m.c.breukink@...> wrote:

>

> --- In Ensoniq-VFX-SD@yahoogroups.com, Claus <clauzii@> wrote:

> >

> > And all the fuses are ok? (You probably checked allready..)

> >

> > Claus,DK

> >

>

> Claus, thank you for your reaction

>

> I have not checked all the fuses, but i will do that.

> I will also look at the circuit around chip 4051 with a scoop and a

> voltmeter.

>



Hi.

I had an "analog" problem with my previous SD-1/32 some years ago that

caused it to sound like the patch was being randomly modulated when it

wasn't.



The SD multiplexes all it's analog input sources (mod wheel, pitch

wheel, etc) and then sends the multiplexed result to the A/D converter

chip. But note. It filters this multiplexed total through a Cap. prior

to being delivered to the A/D.  If this Cap. is faulty, then the A/D

gets sent all sorts of spurious values. I sent my SD-1 to the local

service agent (here in Australia), who had it for two months and

couldn't fix the fault. The chief tech at Yamaha (who had a look at it

as a favor) found it in 30 minutes!! He also provided me with this

explanation. (I'm no technician - you can probably tell).



So I don't have a component ID because I don't have a circuit diagram,

(but try searching old postings, because I have posted this answer

once before...), but just look for the last Cap. prior to the A/D

Converter chip, you may well have your answer.



good luck



Roger









    
	
	




	
	



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