Ramsey Electronics FX-440 Manual page 74

small machine screw and nut supplied. Identify VR1 correctly
without mixing it up with its 5-volt counterpart (VR2).
l\l,Jif
A9b. Insert the 3 VR1 leads into the triangular set of holes while
gently bending the body back towards the board so that the
ting holes line up. Secure VR1 to the board with the screw
, nut. After VR1 is mounted flat, solder and nip the 3 leads.
(
~
. Study the PC board, locate the triangular set of 3 holes for
\Jj
I
VR2 (type 7805), and insert VR2 so that the flat metal tab side is
toward the center of the board. Press VR2 in as far as it will go,
./sf.er
and trim.
1\./'[
Ii~
1.1. Near VR2, install
~100,
a 4. 7 or 1
O uf electrolytic, oriented
for correct polarity.
Stage A PROGRESS TEST:
The power input circuitry is completed and can be tested before
proceeding. Perform the test as follows:
[
~
VMake sure a 1 amp fuse is installed in the fuse holder.
[
~2.
ponnect the fused (+)and black(-) wires to a 12-volt battery or
- /power supply (12-15 volts DC).
( q/3. Connect the black (-) lead of a DC voltmeter or VOM to the ground
plane of the PC board.
[
~Study
the PC board and locate the three points marked
+ 12V, +av and + 5V. (These connections are provided for
rvenience in later modifying or experimenting.)
1/5.
With the power switch turned on, you should get
meter readings of + 12V, +av, and + 5V respectively. (If your
meter probe does not have a fine enough point to make solid
.. contact inside the holes at these 3 points, simply study the
multi-color PC board illustration and look for + 12, + a and + 5
_)'.01ts DC on PC board traces that lead to the 3 voltage points.)
[
~
After you are satisfied that the power input circuitry is working
correctly, disconnect the 12 volt source.
[~
A12. Press J1, the Packet 1/0 DIN connector into
position. Before soldering, make sure that the bottom of the jack
1s perfectly flat against the board. It is best to solder only the
middle pin first, check for straightness, and then solder the other
4 or 6 points. (DIN jack styles may vary; your jack may have
Assm. 14
FX-440