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Alpha Juno 2

Alpha Juno 2

2011-06-14 by Evan Dembskey

Hi all,

I just picked up a AJ2 for a good price. It had some mechanical
problem which I fixed. However, it has one problem that I am not sure
how to approach. Any advice/solutions gladly accepted...

The sound is good when 1 or 2 keys are simultaneously depressed.
However, when I depress 4, or sometimes 3, keys, there is an audible
scratching sound.

I have tested this on different setups, ie headphones, amps, still get
the same sound though. I've used contact cleaner on all the contacts I
can find, so I'm assuming this is a component issue.

Any thoughts?

Regards
Evan

Re: Alpha Juno 2

2011-06-15 by Susie

It sounds like there's a problem with one of the voices. I'm not familiar with the Alphas internals to know how voices are allocated, but in poly mode if you repeatedly press the same key it will usually cycle through the voices - check if you get the scratching sound every sixth note.

It's of course possible that the scratching is distortion on the output caused by the increased amplitude of having multiple voices sounding. Maybe there's a dodgy output stage component?
Susie

--- In vintagesynthrepair@yahoogroups.com, Evan Dembskey <evan.dembskey@...> wrote:
Show quoted textHide quoted text
>
> Hi all,
> 
> I just picked up a AJ2 for a good price. It had some mechanical
> problem which I fixed. However, it has one problem that I am not sure
> how to approach. Any advice/solutions gladly accepted...
> 
> The sound is good when 1 or 2 keys are simultaneously depressed.
> However, when I depress 4, or sometimes 3, keys, there is an audible
> scratching sound.
> 
> I have tested this on different setups, ie headphones, amps, still get
> the same sound though. I've used contact cleaner on all the contacts I
> can find, so I'm assuming this is a component issue.
> 
> Any thoughts?
> 
> Regards
> Evan
>

Re: Alpha Juno 2

2011-06-17 by synthparts

Yes if it is every 6th key then there's a good chance it's a dead VCF/VCA voice chip. I have the in stock if you want one. Doug, synthparts.com

--- In vintagesynthrepair@yahoogroups.com, "Susie" <gardens@...> wrote:
Show quoted textHide quoted text
>
> It sounds like there's a problem with one of the voices. I'm not familiar with the Alphas internals to know how voices are allocated, but in poly mode if you repeatedly press the same key it will usually cycle through the voices - check if you get the scratching sound every sixth note.
> 
> It's of course possible that the scratching is distortion on the output caused by the increased amplitude of having multiple voices sounding. Maybe there's a dodgy output stage component?
> Susie
> 
> --- In vintagesynthrepair@yahoogroups.com, Evan Dembskey <evan.dembskey@> wrote:
> >
> > Hi all,
> > 
> > I just picked up a AJ2 for a good price. It had some mechanical
> > problem which I fixed. However, it has one problem that I am not sure
> > how to approach. Any advice/solutions gladly accepted...
> > 
> > The sound is good when 1 or 2 keys are simultaneously depressed.
> > However, when I depress 4, or sometimes 3, keys, there is an audible
> > scratching sound.
> > 
> > I have tested this on different setups, ie headphones, amps, still get
> > the same sound though. I've used contact cleaner on all the contacts I
> > can find, so I'm assuming this is a component issue.
> > 
> > Any thoughts?
> > 
> > Regards
> > Evan
> >
>

Re: [vintagesynthrepair] Re: Alpha Juno 2

2011-06-19 by Evan Dembskey

Hi all,

It's not every 6th key, it's every time I depress multiple keys. I tested this now by pressing every key 10 times. Every time it sounded fine... until I depress 3 or sometimes 4 keys.

Regards,
Evan
Show quoted textHide quoted text
2011/6/17 synthparts <synthparts@...>

Yes if it is every 6th key then there's a good chance it's a dead VCF/VCA voice chip. I have the in stock if you want one. Doug, synthparts.com



--- In vintagesynthrepair@yahoogroups.com, "Susie" wrote:
>
> It sounds like there's a problem with one of the voices. I'm not familiar with the Alphas internals to know how voices are allocated, but in poly mode if you repeatedly press the same key it will usually cycle through the voices - check if you get the scratching sound every sixth note.
>
> It's of course possible that the scratching is distortion on the output caused by the increased amplitude of having multiple voices sounding. Maybe there's a dodgy output stage component?
> Susie
>
> --- In vintagesynthrepair@yahoogroups.com, Evan Dembskey wrote:
> >
> > Hi all,
> >
> > I just picked up a AJ2 for a good price. It had some mechanical
> > problem which I fixed. However, it has one problem that I am not sure
> > how to approach. Any advice/solutions gladly accepted...
> >
> > The sound is good when 1 or 2 keys are simultaneously depressed.
> > However, when I depress 4, or sometimes 3, keys, there is an audible
> > scratching sound.
> >
> > I have tested this on different setups, ie headphones, amps, still get
> > the same sound though. I've used contact cleaner on all the contacts I
> > can find, so I'm assuming this is a component issue.
> >
> > Any thoughts?
> >
> > Regards
> > Evan
> >
>


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