Ramsey Electronics COMPUTEMP CT255 - Manual (Page 19)

CT255
• 19
Next we will install some of the output voltage divider resistor networks. The
circuit board has been laid out to avoid confusion with these multiple rows, and
we will try to avoid sounding too redundant when installing them, Remember
to save those leads as we will be installing some jumper wires very soon. Pay
particular attention when installing so as not to mount the resistors in the
improper locations.
ˆ 7. Install R36, R33, R29, R26, R21, R19, and R17, all 10K ohm (brown-
black-orange).
ˆ 8. Moving on to the next batch of resistors, install R38, R35, R32, R28,
R25, R20, R18, R16, R13, and R14, all 20K ohm resistors (red-black-
orange). Be sure to solder the ground plane connections of R14 and R38
completely as they will take a little extra time to flow the connection.
ˆ 9. Install resistors R5-R12, 390 ohm (orange-white-brown).
ˆ 10. Using a scrap component lead, form a jumper wire and install in the
JMP1 holes. Jumpers act like electronic “bridges” that carry power or
signals over active traces on the circuit trace side of the board.
ˆ 11. In the same manner, form and install jumper wires JMP2,JMP3 and
JMP4.
That’s getting the hang of it! Believe it or not, you are already halfway through
the assembly of your kit. Recheck your solder connections, touch up any less
than perfect connections that you see. Watch out for any solder bridges on the
IC pins or at the jumper wire connections.
Let’s get to work on that scaling amplifier. We’ll start at the IC and work our
way out in both directions to avoid crowding.
ˆ 12. Install U1, the LMC660 Quad Op-Amp 14 pin IC (marked 324). Make
sure to align the notch or dot associated with pin one with the notch shown
in the parts layout diagram. It may be helpful to gently “rock” the IC on its
side on a hard flat surface before installing to align the rows of pins so that
they slide in easily. Don’t be afraid to use enough solder and heat for a
good solder connection, and be extra careful not to “bridge” any solder
connections together
ˆ 13. Identify and install D9, the 1N4148 small signal diode (glass case with
black band). Remember that diodes are polarized, so face the banded end
as shown in the parts placement diagram. This is one of the more fragile
parts you’ll install so use caution so you don’t flex the leads of the device
at the junction of the lead wire and the glass case. Solder in place and
remove any excess lead.
ˆ 14. Install R24, 1 Meg ohm (brown-black-green).
ˆ 15. Install R3, 10K ohm (brown-black-orange).