SYNTHESIS TECHNOLOGY
PAGE 5
MOTM-850 ASSEMBLY 10/25/01
WWW.SYNTHTECH.COM
A WORD ON SOLDERING
There are 2 very different types of solder used in the kit. Most of the soldering uses
‘Organic Flux’ solder.
This is strictly for use on the pc board, and is NOT to be used
on the front panel wiring!
In order for solder to ‘stick’ to the copper, a chemical called ‘flux’ is embedded in the solder.
The flux leaves a residue on the pc board that should be cleaned with warm water. DO NOT
USE SOAP OR OTHER CLEANSERS. Most of the parts in the kits are ‘waterproof’ and can
be washed in the sink. The flux is OSHA approved for flushing down the drain, so don’t
worry about that! A soft brush is used to gently scrub the board. We recommend a
‘fingernail brush’, which is about 1” x 2” and can be found for about $1.
The other type of solder is called ‘No Clean Flux’;
because as the name implies it does not
require washing. This solder is used for wiring the pots, switches, jacks, etc. This solder is
harder to use on the pc board; because even when melted, it is not very fluid (about the
consistency of toothpaste). We will use it VERY SPARINGLY on the pc board.
OK, let’s get started on the board!
PART #1: SOLDERING THE RESISTORS
Since there are more resistors than anything else, we will start here. If you do not know the
resistor color code, refer to the parts list. Resistors are not polarity sensitive, but the board
will be easier to debug (and look nicer) if you point the first color band in the same direction
for all the parts. The color code is also in the README FIRST document that every
customer receives with his or her first order.
You will start by soldering in ALL of the resistors.
Find
the
RESISTOR
bag.
Find the MOTM-850 blank pc board. There is a copy (larger than actual size) of the
silkscreen which shows where the parts go at the end of this document. It will be
useful if you locate the part on the print first, put the part in the board, then
‘check off’ the silkscreen. All parts are inserted from the side of the board with the
white silkscreen (the “top” side).
NOTE: some reference designators are under the resistor! Be careful.
We will stuff the resistors by value to make things easier. The resistors (and other
long-leaded parts) are inserted on a 0.4 inch spacing. The important thing is to be
sure that the part is sitting all the way down on the board. Push the leads in the
holes, push the part on the board, and then bend the leads on the bottom outwards
to a 45 degree angle (roughly!). This is called ‘cinching the leads’: and keeps the part
from falling out! From the bottom of the board, solder (using the organic flux),
applying heat to the pad for about a half second first, then applying just enough
solder to make a small puddle that looks like a tiny pyramid. Enough solder should
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