[sdiy] Vocal Filter

[Jay Schwichtenberg]

They probably figured it's CMOS, it doesn't use any current, it can't put
noise on the power bus.

Yes, I've used them, but in TTL protos only. The ones I've used only have
the caps between pins 16/14 and 8/7. This works for some logic chips but not
all. First off the socket with caps are usally more expensive than a socket,
cap and the board issues (space & assembly cost). Real big issue is that
sockets suck. Unless you clean everything they start to corrode and you
don't get more than a couple of years use out of something before you have
to reseat the chips or replace the sockets. I've built fairly decent sized
digital stuff and have had problems with it when I first became an engineer.
Live and learn.

I have a love/hate relationship with my Oberheim gear because of sockets.
Every so often I have to tear my stuff apart and clean or replace something.
It's a real pain to tear a Xpander apart and fix it. I've even had chips
fall out of their sockets in a Matrix 6.

Here's an experiment to prove the point. If you have an old card that has
gold edge connector clean them really good. Take a pink pearl eraser or
cleaning powder and get the gold nice and shiny. Don't rub it all off
either. Then take the best isopropyl alcohol you can find (99% if you can
find it) and clean off all oils and grime. Let that dry, take you oily,
dirty fingers and touch the gold. Set it a side for a couple of weeks.
You'll start to see your finger prints on the edge connector. Maybe sooner
depending on temp and humidity.

One thing I do when I put together a computer nowdays is clean the card edge
connectors with alcohol before I put it in a system. So far I haven't had to
tear any of them apart to reseat the cards. Also a lot of edge connectors
are speced for only 10 to 50 insertions. Keep that in mind.

Jay

> -----Original Message-----
> From: owner-synth-diy at dropmix.xs4all.nl
> [mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of Glen
> Sent: Tuesday, December 11, 2001 10:09 PM
> To: Paul Maddox; Synth DIY List
> Subject: Re: [sdiy] Vocal Filter
>
>
> At 04:36 PM 12/11/01 , Paul Maddox wrote:
> >all,
> >
> >hehehe,
> >wanna see INSANE decoupling???
>
> And Crow had written earlier:
> >>   Contrast this board with the TKC board from a CS-80.  In
> their infinite
> >> wisdom, Yamaha decided the board needed no decoupling at all.
> Thus, the
> >> 29-chip board (all 4000-series CMOS) has no decoupling caps:
>
> If I understand correctly, it is possible to buy chip sockets with caps
> built-in. I don't suppose either PPG or Yamaha had ever used
> something like
> this?
>
> Has anyone on the list used such sockets? It seems like a good
> idea for digital
> logic chips. However, I could see how it might confuse a
> repairman working on a
> circuit board using such sockets.
>
>
> Later,
> Glen
>
>