TelePost LP-100, Manual

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12
Assembly cont’d
Initial checkout of main board.
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Step 1. Make sure that your bench is clean and the PCB is not sitting on any cut off component leads. Connect supplied power
cable to a supply of 12-15 VDC. The dashed white lead on the supplied power cable is the +lead (center pin). Make sure you have
a jumper installed at JP2. Using your DMM, check for 5.0 VDC at pin 3 of U2. The voltage should be within 0.25V of 5.0 VDC.
~7
mA.
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Remove power and install L2, U7, Y1 and the PIC. Temporarily connect the PLED display. Be careful to make sure there is nothing
on your bench which could short out anything on the PLED PCB. The ribbon cable should be oriented as shown in the interior
photo below. Make sure that the ribbon connectors are centered on the headers at both ends.
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Step 2. Power the board up again, and verify that you are seeing the “splash” screen with version and copyright information,
followed by the main LP-100 screen. The main screen should look like the screen on the photo at the top of the “Operation” section
of this manual. If you don’t see the display, adjust the setting of R8. The proper setting is just at the point where the display
reaches maximum brightness. This will ensure that the brightness drops to the proper level when the first step of the screen saver
timer is reached. A finer adjustment can be made after the screen-saver starts. The correct voltage for the PLED at the junction of
R8 and R15 is 3.0V at full brightness
while displaying the main screen . It will drop to 2.4 – 2.5V in the screen saver mode. ~35
mA
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Step 3. Install L1, L3, U5, and U8. ~82 mA . Temporarily enter the Setup mode by briefly pressing the Mode (SW1) and Alarm
(SW2) buttons almost simultaneously. The Mode button should be pressed slightly ahead of the Alarm button. NOTE: Starting with
firmware version 1.1.44, entering (or exiting) Setup is accomplished by holding the Mode button for about a second until the screen
changes.
You should now see the first Calibrate screen, shown below for firmware prior to 1.1.47. The second screen is for
firmware 1.1.47 and after. This screen shows the reference voltage generated by U1 (the gain/phase detector), the Received
Signal Strength Indicator voltage from U9 (the AGC chip) and temperature in degrees F and C (from the temp sensor, U7).
Note:
the RSSI reading shown in this photo is with RF power applied. The resting voltage with no RF is generally between .150 and .250.
Newer firmware displays Temp in degrees C or F depending on the selection.
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Step 4. Install L5, L7, U4 and U6 and check the current. ~160 mA. If all is well, set the board aside until the coupler assembly is
completed to allow checkout of the power detector circuit and frequency counter.