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UML305DEV BOARD ASSEMBLY GUIDE
1. WEAR EYE PROTECTION
2. WASH HANDS AFTER SOLDERING.
3. BE CAREFUL WITH THE SOLDERING IRON.
Good and Bad Solder Joints The following two diagrams illustrate a proper solder joint and an incorrect one. Its worth studying these diagrams so that you can identify a good joint and fix a bad one!
With a bad solder joint (sometimes called a cold solder joint), the solder has balled up around the component lead. It has not flowed through the board, and it does not adhere to the board. The solder appears dark and wrinkled. BOARD ASSEMBLY Following are step-by-step instructions for assembling the board. The basic strategy is to install the flattest components first and finish with the thicker ones. You may wish to check off each step as it is completed. Resistor Description Lets start with the resistors. Theyre marked with four colored bands indicating their value. Three bands indicate the value according to the following table. (The fourth band is gold or silver, indicating the precision of the value [gold=5%, silver=10%]):
Resistor Installation Before starting installation, please compare the 1K (brown, black, red ) and the 10K (brown, black, orange) so you can discern the difference between the red and orange exponent bands. o R2, 1K, brown, black, red o R4, 1K, brown, black, red o R6, 1K, brown, black, red o R5, 2.2K, red, red, red o R7, 10K, brown, black, orange o R8, 10K, brown, black, orange o R1, 47K, yellow, violet, orange o R3, 47K, yellow, violet, orange Resistor Networks These components package a bunch of resistors into one device. The ones we are using are polarized because they contain 9 resistors, with one common pin. This pin is marked with a dot. Make sure to install the dotted pin in the PCB hole marked with a tiny 1. o RN1, 1K, labeled ctsk 102 o RN2, 1K, labeled ctsk 102 LEDs The green and red LEDs are installed next. These are polarized so dont install them backward. The short lead of the LED is negative, and this goes in the square hole. Note that some LED positions have their square hole to the left, while others are on the right! o LED1, HLMP1790, green o LED2, HLMP1790, green o LED3, HLMP1790, green o LED4, HLMP1790, green o LED5, HLMP1790, green o LED6, HLMP1790, green o LED7, HLMP1790, green o LED8, HLMP1790, green o LED9, HLMP1790, green o LED11, HLMP1790, green o LED10, HLMP1700, red o LED12, HLMP1700, red IC Socket The 16-pin DIP socket goes in position for the MAX232 chip. While the socket itself is not polarized, the MAX232 chip must be installled in the correct (of two choices) orientation. Therefore it is desireable to install the socket in the way that indicates the correct position for the chip it holds. Look closely at the socket, and notice the little half-circle dimple along one of the short edges. Then find this same dimple in the markings on the circuit board (next to the text IC1). When you install the socket, line up the dimples. Later, when you install the MAX232 chip, the dimple on the chip will line up with the dimple on the socket. o DIP1, 16-pin socket, in position of IC1 Pushbutton Switches Switches 1 through 4 are pushbutton switches. These are slightly oblong (rectangular) when inserted into the board. When you go to insert these into the board, they should fit easily. If you have to bend the pins excessivelyyoure doing it wrong. Turn the switch 90 degrees and try that position. o SW1, pushbutton switch o SW2, pushbutton switch o SW3, pushbutton switch o SW4, pushbutton switch Diode Diode D1 limits the amount of current that can flow from the batteries and also drops 0.6v to bring the 4AA supply into a better range for use with 5v logic. The diode is polarized. Line up the band on the diode with the band on the component marking (i.e., toward the right). o D1, 1N4001 diode Capacitors There are two different varieties of capacitors used. The small cylindrical type are electrolytics. These are polarized and must not be installed backward. The flat type is a monolithic. This is non-polarized and may be installed in either rotation. For the electrolyics, find the band on the device with a minus symbol. This is the negative () lead. The other lead is the positive (+) lead. Insert the positive lead into the pin marked with a + symbol on the circuit board. o C5, 47µF, electrolytic capacitor o C1, 10µF, electrolytic capacitor o C2, 10µF, electrolytic capacitor o C3, 10µF, electrolytic capacitor o C4, 10µF, electrolytic capacitor o C6, 0.1µF, monolithic capacitor Transistors There are two different types of transistors in the designtwo NPNs and two PNPs. If you put the PNPs in the NPN positions (or vice-versa), the logic probe circuit wont work. Note that the component numbering is NOT sequential, e.g., the NPNs are Q1 and Q4. The component markings on the circuit board indicate how the transistors should be aligned. Bend the middle pin backward to fit into the hole between the two outer pin positions. o Q1, NPN transistor, 2N3904 o Q4, NPN transistor, 2N3904 o Q2, PNP transistor, 2N3906 o Q3, PNP transistor, 2N3906 Slide Switches The two remaining switches are SW6, the power switch, and SW5, the 4-position DIP switch. The power switch can only be installed one way. o SW6, SPDT slide switch The DIP switch will work either way, but lets all do it the same way so all of our boards come out the same. Please line up the numeral 1 on the switch with the label S5 on the circuit board. o SW5, 4position DIP switch Piezo Beeper The large round beeper goes in the component position marked X1. Orientation does not matter. o X1, piezo beeper DB9 Jack The DB9 jack mounts in the position labeled J1. Push it through carefully but firmly, making sure all nine pins go into their holes properly. Check that all nine pins are through their correct holes on the circuit board before soldering! Add lots of solder to the two through-the-board mounting pegs. These provide a strong mechanical connection to hold the jack in place. o J1, DB9 connector Strip Header The strip header provided has 36 pin positions. The circuit board requires 28 pins. The extra 8 must be cut off. There are a couple of ways to do this. 1. Use a razor knife to score the header in the groove where you want to it to split. Repeatedly score both sides of the same groove, then firmly snap the part in two. Note: you must score the groove repeatedly in order to get it to snap properly. If you just try to snap it without scoring, or with not enough scoring, it may break somewhere else, or destroy the edge pin near the snap. 2. Using diagonal cutters, cut the strip in half. However, dont try to cut it at a groove, because one side of the split will get damaged, and you wont be able to control whether its the side you care about (the 28-long piece) or the side you dont (the 8-long piece). So cut in the middle of a pin position, make sure that one side of the strip will still have 28 intact pins. You should end up with a 28-long piece and a 7-long piece. After you produce the intact 28-pin piece, solder it into the positions marked SV1 through SV4. Solder the two ends and make sure the socket is flat with the circuit board before soldering the whole thing! o SV1-4, 28-long strip header socket Battery Pack The battery pack mounts down through the top of the board like the other components. Its leads are inserted into the hole marked with a minus sign and the adjacent square hole. Both are located along the top edge of the board, toward the left. o BATT1, 4-AA cell holder MAX232 Chip The MAX232 chip can now be installed in its socket. Make sure the notch on the chip is toward the left. o U1, MAX232CPE serial transceiver Assembly is now complete! Were ready for testing.
Now, start typing on the PC keyboard. You should see:
Now type on the PC keyboard, and:
Piezo Beeper This test is easy. Connect a jumper wire from the PIEZO pin to one of the pushbutton switches (e.g., SW1). When you press the switch, you should hear a little click from the piezo. When you release the switch, it should click again. Note: its just a little click, not a strong tone! o piezo beeperclicks gently when switch is pressed and released. Last modified: Friday, 20-Sep-2002 12:46:36 EDT by |