Elecraft K1BKLTKT LCD Mod Kit User Manual
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21.
The LED current-limiting resistor must now be
chosen. A value of 330 ohms will give you a current
drain of about 6mA with adequate illumination. A
value of 200 ohms will provide a somewhat brighter
display, but with a current drain of about 10mA.
Using the illustration at right, install the selected
current-limiting resistor between the ANODE (A)
pin of the backlight LED and pin 8 of U3 (+6VDC).
Refer to the illustration and the other side of the
Front Panel PC board to confirm the position of U3-8.
22.
Following the illustration above, use one of the clipped resistor leads and install a jumper wire
between the cathode (K) lead of the backlight LED and the grounded pin 1 of at U3. Note that
the insulator card assembly is covering most of the pins of U3, so you must be sure that you have
found pin 1 of U3 before you attach this short jumper wire. Pin U13-1 is just to the left of Pin 24
of the LCD display (DS1).
23.
Carefully reinstall U1 into its socket. Ensure that ALL of the IC pins are inside the socket before
you press it into place.
24.
In this step, you will install the NEW LCD display. It is
IMPORTANT that you install the LCD properly, so the
small bump on the side of the display is pointing to the left.
See the illustration at right for assistance in identifying the
proper orientation of the LCD display when it is installed.
CAREFULLY install the LCD display over the top of the
backlight, taking care to ensure that all of the LCD display pins are seated into their mating holes
on the PC board. The pins should enter all of the PC board holes, but they should just. be flush
with the back side of the PC board, as they were when the original LCD display was installed.
DO NOT solder the LCD into the PC board yet.
You want to ensure that you have adequate back
lighting before you complete the installation by
soldering the pins of the LCD.
25.
Carefully plug the Front Panel PC board back into the
K1 RF board, connect power to the radio, and press
the ON/OFF switch. This should cause the backlight
to illuminate so, with the room lighting dimmed, you can see how bright the LCD will be when it
is finally soldered into place. Note that there is a good chance that few, if any, of the LCD
elements will turn on because they have not been electrically connected to the PC board yet.