Logikit CMOS-4 Manual

Dear Logikit CMOS-4 Keyer owner:
We have found that the PC board for your Logikit CMOS 4 keyer was designed such that the
5-volt voltage regulator draws a steady current of about 1.5 mA from the battery pack at all
times, regardless of whether the keyer is in use or not. This will drain the batteries within a few
months.
The following steps will fix the problem:
Disassembly:
1) Remove the four 4-40 screws securing the top cover of the keyer and set both the (4)
screws and the top cover aside.
2) Remove the center battery from the battery pack and set it aside.
3) Remove the two 4-40 screws securing the pushbutton PC board and set them aside.
4) CAREFULLY remove the SPEED control mounting hardware and set it aside.
5) Remove the two 4-40 nuts and two split washers securing the keyer PC board and set
them aside.
6) Lift the keyer PC board away from the screws over which it is mounted, and set the two
white nylon standoffs aside.
Note that it will probably be easier for you to allow the SPEED control and the push-
button PC board to hang free as you remove the keyer PC board.
Modification of the Keyer PC Board:
7) Turn the keyer over and slide the keyer PC board out slightly from the case (see Figure 1
on the following page).
8) Locate the PC board trace which connects the ungrounded side of C2 to the cathode
(banded) end of D3 (see Figure 2 on the following page).
9) Using a SHARP a sharp knife (an X-acto knife, or single-edged razor blade are
preferable) CAREFULLY cut the trace between C2 and the cathode (banded) end of D3
(see Figure 3 on the following page),
Idiom Press
P.O. Box 1985
Grants Pass,OR 97528
www.idiompress.com
sales@Idiompress.com