Onkyo IC REMOVAL Service Manual

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boards cop per traces. One word of caution, th is techn ique takes som e practice. You are using a sharp razor kn ife that W ILL cut the bo ards traces if you use too much force while cutting through the ICs pins. Check the board be fore you solder the new IC in place. It is highly recomm ended that you practice this m ethod on som e scrap boards before trying it on a cu sto mers unit. Wire removal method: Apply flux to the IC pins. Us e desolder braid to rem ove as much solder as possib le from each pin. Thread fine stainles s steel or enam el coated wire under one row of pins. Secure one end of the wire on a near by com ponent (i.e. a large Electrolytic capacitor). Starting at the l oose end, heat each pin and pull wire sim ultaneously. Pull the wire as cl os e to the PCB as practical. As the solder between the pin and pad m elts , the wire will pop out and leave the pin standing free of the pad. Repeat these steps for the other sides . Hot air desoldering tool: There are several typ es of hot air desoldering system s. Desoldering tools range from the inexpensive portable pyropen type that uses butane fuel and a catalytic burner to produce heat, to the sophist icated tem perature controlled, auto-tim ed, variab le suction, m ulti-n ozzle ho t air system s that can cos t yo u hundreds or thousands of dollars. If you are on a tight budget, a handy device to get the job done is the pyropen or hot air torch. These hot air, butane fueled, catalytic burner devices can be purchased for under $100.00. To use this type of hot air device you ha ve to ignite the to rch, and adjust the tem perature. After it warm s up place the nozzle tip about ¾ to 1 inch abov e the legs of the IC you wish to rem ove. Move the nozzle tip around the IC to uniform ly heat the ICs legs until th e solder liqu efies. Once the solder has liquefied use a dental pick or sim ilar device to lift the IC away from the board. As with other m ethods described here, practice rem oving ICs from a scrap board to hone your technique bef ore you work on a custom ers unit.

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IC Replacement Soldering Techniques: OK, now that you rem oved the IC from the board, how do you solder the replacem ent IC on the board ? Here are som e basic techniqu es for soldering a replacem ent IC to the P C board. First, m ake sure the lands are CLEAN. That m eans rem oving all solder and f lux left behind during the IC extraction process. Next, check the board to m ake sure th e traces are no t broken, cut or lifted. P lace the n ew IC on the bo ard and position it so all of the pins are properl y aligned (IC pin 1 to board land #1, etc.) on the board. Once you have verified the traces are properly aligned, secure the new IC to the board. O ne m ethod to secure the IC is to us e a piece of clear adhesi ve tape to ho ld the IC to the board. Another m ethod would be to ap ply pressure to the top of the IC using a probe or tweezer to keep it in place w hile so lderin g it. Secur e the IC a nd s older . Once the IC is secured, solder the corners of th e IC first to hold the chip in place. If you are using tape to secure the IC you can rem ove it once you have the corners soldered in place. Add a bit of solder flux (liqu id or paste) to the unsoldered pins and then solder the rem aining pins. Adding the flux allows the m olten solder to adhere to the lands and IC pins which will r educe the num ber of unreliab le solder conn ections. A good sold er connection. Next, check your work! Re move solder bridge s between the ICs pi ns with desoldering braid and reflow any doubtful solder connect ions. You m ay want to use a m agnifying glass to help check your work. Here are 10 basic steps to successfully soldering an IC (or any com ponent): 1. Make sure all parts are clean a nd free from dirt and grease. 2. Secure the IC or com ponent firm ly to the board. 3. "Tin" th e iro n tip with a sm all a mount of solder. 4. Clean the tip of the hot soldering iron on a dam p sponge. 5. You can add a tiny am ount of fres h solder to the clean tip. 6. Heat all par ts of the join t with the iron for a second or so. 7. Continue heating and apply su fficien t rosin core solder to form a s mooth joint. 8. It only takes two or three s econds at most, to solder the average p c board joint. 9. Do not m ove parts until the solder has cooled. 10. Check you work for solder bridges and cold solder connections.