Patches and discussion for Ensoniq VFX family

(Note, all numbers in here are SD-1 numbers, but the VFX/VFX-SD is  
similar enough to be pretty much the same situation - just different  
numbers)


A lot of the problem is that they're all in parallel, so if the current  
drain exceeds 8A on the 5V line, assuming things are fine, then ALL of  
them will blow (1 fuses blows, you have 8A flowing thru 2 3A fuses (6A  
total), so the next one blows, and so on).

Fuses age, its a fact of life, they age like lightbulbs do, though not  
as fast. So after a while, you're not getting 8A current protection,  
you're getting 6A, or 4A, and the margins from 'normal current drain'  
and 'current drain enough to blow the fuses' gets smaller. Couple all  
this with a notoriously dodgy power supply system (who hasn't had data  
corruption on a VFX/VFX-SD/SD-1 from fluctuations on the mains power ?)  
and you get a recipe for dead fuses every year or so. If there is even  
a tiny imperfection with a new fuse, it too may contribute to this  
domino effect, and possibly very early on (perhaps that was the problem  
when you had them blow after 2hrs)

I've toyed, occasionally, with the idea of replacing the 4 2A fuses on  
the 5A line, and the 2 2A fuses on the 12v line, with resettable  
thermal fuses (the kind used in PC power supplies - they auto-reset  
after being powered off for a few minutes) but each time I think about  
it, by the time I actually contemplate ordering them, and doing the  
job, the fuses I replaced are 'still running' :)

Replacing the fuses with a higher rating fuse is a bad idea, if  
something DOES genuinely go bad, then you have less protection, and are  
more likely to suffer real permanent damage inside the VFX. Replacing  
them with a fuse that doesn't cost anything to reset each time, is  
probably a much better option.

Replacing the fuses with resettable fuses, would probably involve  
soldering the new ones over one (or more) of the fuse holders for the  
2A fuses, though you may be able to find resettable fuses in a standard  
5x20mm fuse package, I saw some like that once a few years ago...

On Thursday, June 5, 2003, at 03:40  PM, amartinez@... wrote:

>
> To Geren W. Mortensen, Jr.:
>
> Hello from Barcelona (Spain)
>
> I really don't know the problem that causes the 2A fuses to blow. I  
> own a
> VFX-SD II (keyboard calibration already fixed) and I've suffered the  
> same
> trouble 5 times, two or three years ago.
> My only solution was replacing time after time the fuses (sometimes  
> they
> lasted for 2 hours, sometimes for weeks). At the beginning I thought it
> could be a peak on the electrical line, so I bought a very simple and  
> cheap
> power stabiliser but it had no use. I was tired enough for thinking to
> install fuses of a higher amperage (and wait what happened...)  but  
> finally
> the problem disappeared as it came. Since then the VFX has not failed
> again.
> I know this is not too helpful but at least it gives some hope...
>
> Hasta pronto.
>
> Alfons Martínez
> amartinez@...
>
>
> ------------------------ Yahoo! Groups Sponsor  
> ---------------------~-->
> Get A Free Psychic Reading! Your Online Answer To Life's Important  
> Questions.
> http://us.click.yahoo.com/Lj3uPC/Me7FAA/ySSFAA/mjFolB/TM
> --------------------------------------------------------------------- 
> ~->
>
> To unsubscribe from this group, send an email to:
> Ensoniq-VFX-SD-unsubscribe@egroups.com
>
>
>
> Your use of Yahoo! Groups is subject to  
> http://docs.yahoo.com/info/terms/
>
>
>