Anyone have a Schematic for an Alesis QuadraSynth?
On 6/19/2019 7:57 AM, Scott Dorsey wrote:
In article , Paul wrote:
You can see that the pitch and modulation wheels are touching.
Really lousy design. Yes, I might have to take a blade to it.
This is consumer equipment. The material and manufacture is designed for
a three to five year lifespan.
Date of manufactu About 1994. 25 year old board.
Now that the pitch and modulation pots have been replaced,
the wheels have about 1/8th of an inch between them. I didn't
sand off that much material, so it looks like they might have been
assembled incorrectly at some point.
You'll notice that the contacts are corroding because they aren't hard gold.
Hard gold contacts would drive up the price of the keyboard mechanism by a
factor of ten. So they don't do that.
The keyboard velocity contacts are matte black pads, which cleaned
up nicely with 91% isopropyl alcohol. So now the entire keyboard
works fine.
The knobs are inexpensive urethane that isn't completely set and swells up
after a few years. That saved a dollar or so and really doesn't shorten
the service lifetime since other things will have broken by then.
The worst thing on this unit, are the plastic screw posts on the
keyboard mechanism, that you screw into from the back of the unit.
Maybe about 30% of them have either broken off completely, or have
cracked or split open, rendering them useless to hold a screw tight.
It could be the few screws that were left, were not the original
screws, and so they could be a bit too long, which may have encouraged
the cracking. So I put in shorter screws on the remaining posts that
were open, and it seems to be good enough for now.
Now, Alesis DOES provide an actual service manual... even if it does not
have full schematics and board layouts, it at least has block diagrams and
pinouts. So Alesis does get some credit for trying to make the system
serviceable in a way that most consumer gear is not. The days of being able
to order a Sam's Photofact on the latest consumer product are mostly over.
The stuff sold in your local MI store is pretty much all designed like
other consumer electronics today, and sold in a similar way.
--scott
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