SAM-III Construction Manual
See last page for document and copyright information, File: SAM-III Magnetometer Construction.doc, Page 14
+
JP1 polarizing
flange
Polarizing
slot this side
Polarizing
slot this side
Relay K1
Solder the two headers JP1 and JP2. JP1 has a polarizing flange on one side and it must be
installed with the flange toward the pluggable terminal block as shown in the illustration above.
JP2 is a simple 2-pin header and must be installed with the shorter pins soldered to the PCB
Solder the PCB header sockets SV1 and SV2. The CENTER polarizing aperture (center polarizing
slot) must be on the side toward the 40 pin IC socket
Solder the variable resistor P1 (47k or 50k)
Solder the variable resistors P2, and P3 (10k)
Solder the reset pushbutton S1 (either way)
Locate the reed relay K1 and hold it with the pins down and the text facing you. There is a small
dimple or indentation on the upper-left corner. See illustration. The relay has an internal diode
across the coil winding to prevent inductive kickback, so it is polarity sensitive. Place the relay on
the PCB so the
+
mark on the relay corresponds with the
+
on the PCB illustration above; the
text on the relay must be on the side toward the 34-pin header. The relay location is marked K1
on the PCB silkscreen but only the 1 is visible
Solder ICs U6 (MAX232E), U7 (74HCT00), U8 (RTC72421), U9 (74HCT00), U11 (LM358N) and OK1
(CNY17F) and transistor Q2; Match the dimple on the end of each IC with the silkscreen on the
PCB. Some CNY17F, OK1, have a depression along the side with pin 1. Some builders prefer to
install DIL sockets (not supplied) rather than solder the ICs directly to the PCB; if so, install them
now
Solder the ceramic capacitors C19 and C20. If you had to modify the 40-pin DIL socket by cutting
the webs, bend the capacitors flat on the PCB away from the crystal location and then solder
Check the bottom of the crystal (Q1). If it does not have a thin insulating wafer, cut one from a
piece of paper. The wafer or paper raises the crystal a little above the PCB and prevents it from
touching the traces. Solder crystal Q1. DO NOT overheat the crystal as it could be damaged
All controller PCB soldering is done.
Indentation
Polarity indicator
